# DIODE LASER SPECTROSCOPY (160309)

Size: px
Start display at page:

## Transcription

1 DIODE LASER SPECTROSCOPY (160309) Introduction The purpose of this laboratory exercise is to illustrate how we may investigate tiny energy splittings in an atomic system using laser spectroscopy. As an example we are going to measure the ground state hyperfine splitting in Rubidium ( 87 Rb and/or 85 Rb), arising from the interaction of the magnetic field created by the orbiting electrons and the magnetic moment due to the nuclear spin. Other examples of small energy effects that could be measured in a similar way are isotope shifts (see figure 2 below) and Zeeman splittings in external magnetic fields. A central concept in the investigation of small energy splittings is that of line width, and its influence on the experimental resolution. A very simple type of laser, still capable of (limited) wavelength scanning, is the diode laser, which we are going to use. You will also find that it is possible to accurately measure gas concentrations using laser techniques. This is useful in many practical applications, e.g. measuring the concentration of oxygen in a respiratory tube in an operating room or air pollutants in the atmosphere across a city. During the laboratory exercise you will also practice your ability to align optical components, use a Fabry-Pérot interferometer and a digital oscilloscope. Preparation Hyperfine interactions and isotope effects are discussed in Spectrophysics 3.8 and the different line broadening mechanisms in and These subjects are also treated by Foot in and , respectively. The Fabry-Pérot etalon, used here to obtain an accurate frequency scale, is discussed in the instructions to the Zeeman lab. Safety. The diode laser emits intense and invisible light (780 nm). Hence you must wear protective goggles at all times when a laser is active. Preparatory exercises 1. Line widths. The wavelength of the D 2 -line (5s 2 S 1/2-5p 2 P 3/2 ) in Rubidium is nm. a) What is the frequency of the transition? b) What is the natural frequency line width of this transition if the upper level has a lifetime of 26.0 ns? c) What is the Doppler frequency line width at 20 and 120 C, respectively? d) What is the line widths calculated above expressed in nm at 780 nm? 2. Figure 2 shows fluorescence spectrum of the D 2 -linje in Rubidium recorded using a diode laser that excites a collimated beam of Rb-atoms, i.e. an almost Doppler free measurement. a) Derive the frequency differences between the 87 Rb peaks. Use the known free spectral range in the Fabry-Pérot recording done simultaneously to 1

2 obtain your frequency scale. Are your results consistent with the data given in Figure 1? b) Determine the line width (FWHM) of the largest peak and compare with the results above. c) Assume now, that instead of a collimated beam experiment, we make the measurements directly in a gas cell at room temperature. Can you then resolve the hyperfine structure in the ground state (5s) and in the excited (5p) state? 3. The distance between the mirrored surfaces in a typical Fabry- Pérot etalon is cm and the refractive index of the material is n = 1,511. What is the free spectral rage of the etalon? 4. At room temperature (20 C) the vapor pressure of rubidium is Pa. How many atoms per m 3 are there then in a cell with rubidium? Hyperfine structure in Rubidium In Rubidium the resonance lines have the following wavelengths: 5s 2 S 1/2-5p 2 P 1/2 794,7 nm (historically called the D 1 -line) 5s 2 S 1/2-5p 2 P 3/2 780,2 nm (historically called the D 2 -line) The designations D 1 and D 2 are frequently used for the resonance lines in alkali metals, but have no meaning what so ever. Naturally occurring Rubidium have 2 isotopes 85 Rb (73%) and 87 Rb (27%), but we are going to use cells that contain either pure 85 or 87 Rubidium. Figure 1 shows the hyperfine structure in the 2 levels in 87 Rb, where the nuclear spin is I = 3/2. The energy differences due to the hyperfine interaction are given in frequency units ( E/h). The selection rule for transitions between hyperfine levels is: F = 0, 1 (F = 0 to F = 0 forbidden), where F is the quantum number describing the total angular momentum F = I + J. F MHz 157 MHz 72 MHz Rb F MHz Figure 1. Hyperfine structure in the ground state 5s 2 S 1/2 and in the excited state 5p 2 P 3/2 in 87 Rb. The figure is not to scale. The six transitions are numbered according to increasing frequency, and an experimental spectrum is shown in Figure 2. 2

3 85 Rb 85 Rb 87 Rb 3 87 Rb Lasertemperatur Laserfrekvens Laser frequency Figure 2. A fluorescence spectrum of the D 2 -linje in naturally occurring Rubidium ( 85 Rb and 87 Rb), recorded using a narrow band laser that excites a collimated beam of Rb-atoms. The numbers on the 87 Rb peaks refer to the transitions in Figure 1. As the laser scans, part of the light is simultaneously sent through a Fabry- Pérot etalon with a free spectral range of 141 MHz, and the interference fringes are also recorded. 3

4 The Diode laser - Distributed Feedback Lasers A laser diode is a laser where the active medium is a semiconductor doped with materials from group III (Al, Ga, In) or group V (N, P, As, Sb). The most common type of laser diode is formed from a p-n junction and powered by injected electric current. A p-n junction consists of two doped semiconductors, one n-doped and the other p- doped, that are put in close contact with each other. The band gap structure of a p-n junction is shown in the left part of Figure 3. The Fermi levels of the two doped materials lie at the same level. If a forward voltage is applied over the p-n junction, a potential difference is established between the Fermi levels of the p-and-n side, which is shown in the right part of Figure 3. In this case, there will be population inversion in the so-called depletion region between the p-and-n side, with electrons in the conduction band and holes in the valence band. This means it is possible to get stimulated emission in this region. Figure 3: Left: The energy level diagram of a p-n junction. The Fermi energy is at the same level for the p and n side. Right: The energy level diagram of a forwardbiased p-n junction. Population inversion is achieved in the depletion region between the p and n side, and this makes stimulated emission possible. Diode lasers are good light sources for absorption spectroscopy due to their stable and smooth wavelength tunability as well as being easy to handle and control. Changing the current and/or the temperature of the diode results in an altered output wavelength because of changes in the band gap, the refractive index and the laser gain-curve. To study the hyperfine structure in Rb we will use a diode laser that emits light in a narrow band around 780 nm. The laser is shown in Figure 4 and is made of GaAs. Figure 4. The diode laser is inside a sealed capsule. In our experiments we are going to use an advanced form of diode laser, called a Distributed Feedback Laser (DFB). To stabilize the lasing wavelength, a diffraction grating is etched close to the p-n junction of the diode. This grating acts like an optical filter, causing a single wavelength to be fed back to the gain region and laze. For a DFB temperature tuning results in a wavelength shift of 0.1 nm/k or -25 GHz/K whereas current tuning gives a shift of 1 10 GHz/mA. Practically this 4

5 means that the temperature is used for coarse tuning and the injection current for fine tuning of the output wavelength The output power of the laser depends strongly on the current over the p-n junction, see Figure 5. For low currents the component works like an LED, and only for currents above a threshold value do we get laser action. 5 P 0 /mw C 60 C 10 C I F /ma Figure 5. The output power P 0 of the laser as a function of current I F. Our DFB lasers have a maximum output of 100 mw, which is very dangerous to the eyes, particularly since the blinking reflex is not present with invisible light. Hence you must wear protective goggles at all times when a laser is active. Note, not only yours but any laser in the room To achieve a smooth and continuous wavelength scan in our experiments we will use the following technique. A function generator produces triangular wave shaped voltage pulses which are fed to the laser driver unit where they are converted to current ramps around a set current value which, finally, produces a smooth wavelength scan around a set wavelength. By monitoring the laser intensity after passing through a gas cell with Rubidium as a function of time on an oscilloscope we may thus see an atomic absorption spectrum in real time. Beer-Lambert law A gas containing a certain type of atoms will absorb light at different wavelengths according to its energy levels diagram and the transition rules between different levels. If light of a resonance wavelength for a certain atom is sent through a gas containing these atoms, the light will be absorbed. The intensity of the light will then decrease as it passes through the gas. The decrease is governed by the Beer- Lambert law I = I 0 e μx Where I 0 is the intensity before passing through the gas, I is the intensity after the gas, x is the distance that the light passes through the gas and μ is the linear absorption coefficient. The Beer-Lambert law also works for the absorption of light in liquids and solids. 5

6 The linear absorption coefficient μ is a measure of how much light is absorbed over a certain distance in the absorbing gas. μ depends on the transition propabilities of the transition in the absorbing atom or molecule, and also depends on the concentration of the absorbing species. For an absorption line with a large μ, more light will be absorbed over the same distance x than for an absorption line with a smaller μ. Tunable diode laser absorption spectroscopy A common way to perform absorption spectroscopy is to shine laser light through a gas and then sweep the wavelength of the laser over the absorption line of the gas. Then the decrease in transmitted intensity through the gas when the laser is tuned to the absorption wavelength is measured. Diode lasers are ideal for this task since it is easy to alter the wavelength by changing the driving current to the laser. The use of diode lasers for absorption spectroscopy has been given the name Tunable diode laser absorption spectroscopy (TDLAS). As stated above, the output wavelength of a laser diode can be tuned over a certain range of wavelengths by changing the temperature and/or the driving current to the diode. The temperature is mostly used to set the laser to roughly the correct wavelength, while the current is used to sweep the wavelength repeatedly over the absorption line to be studied. In this laboratory exercise, this will be achieved by modulating the driving current with a triangular wave modulation, i.e. the driving current will change linearly over time, sweeping back and forth between two set values. This way, the wavelength of the laser will also change linearly back and forth between two set values. The output power of the diode laser also changes when the driving current is modulated. Therefore, the laser power (or laser intensity) from a diode laser will also follow a triangular curve, where different points in the sweep correspond to different wavelengths as well as different intensities. When the light passes the resonance wavelength, the intensity of the transmitted light decreases; see Figure 6. Figure 6: The principles of analyzing an absorption signal with TDLAS. Left: The laser output power as a function of time during one sweep of the driving current. Each point on the slope corresponds to a different frequency of the laser light. Right: The light intensity transmitted through the sample decreases every time the laser scans over the resonance frequency. The transmitted light at an absorption peak is related to the incoming light by the Beer-Lambert law, I = I 0 e μx. Figure 7 illustrates how I 0 and I can be measured from an absorption spectrum. I 0 is the intensity of the light without any absorbing atoms, which may be estimated from extrapolating the laser intensity curve over the absorption line. The linear absorption coefficient μ of the absorption line can be calculated from I 0 and I using the Beer-Lambert law if we know the distance x the laser passes through the absorbing gas. 6

7 Figure 7: A typical absorption spectrum from a diode laser. The laser frequency is tuned by changing the driving current of the laser. The laser intensity increases as the driving current increases (as illustrated in Figure 6). The absorption is seen as a decrease in the transmitted laser intensity at a certain frequency of the laser light. The transmitted light (I) and the light before absorption (I 0 ) are marked in the figure. The line width Δf FWHM of the absorption line is also marked in the figure. As stated before, the linear absorption coefficient μ depends on the concentration of the absorbing gas. It is possible to relate gas concentration n in the gas cell to μ using the following approximate relation: n = 8π τ μ Δf FWHM λ 2 G 1 G 2 where τ is the lifetime of the excited state, Δf FWHM is the linewidth of the absorption line, λ is the wavelength of the laser and G 1 and G 2 are the statistical weights for the excited and ground states for the transition. The advantages with TDLAS are many compared with other types of absorption spectroscopy. Diode lasers are small and compact and relatively inexpensive, compared with other tunable laser light sources. They can be made to have singlemode operation and narrow linewidths. It is easy to sweep the wavelength of the laser by applying a ramped current. The disadvantages of TDLAS are mainly that there is a limited choice of wavelength range, and that the tuning range is relatively small. A laser diode can normally only be tuned a few nm, which is troublesome if many absorption lines are to be studied quasi-simultaneously. There are still no diode lasers in the UV-region (ultra-violet), and diodes in the mid-ir-and-ir regions normally need powerful cooling to work. Fabry Pérot etalon A Fabry-Pérot etalon is a useful tool for frequency calibration in TDLAS. It normally consists of a glass cylinder with two parallel, highly reflective surfaces. Because of this, light that passes through the etalon will undergo multiple reflections, and the light will pass many times through the etalon. This is illustrated in Figure 8. The light is both transmitted and reflected in each surface. The reflected beams are drawn beside the transmitted beams to show the effect more clearly (in reality, all beams pass on top of each other). After the etalon, the light that passed straight through the etalon will interfere with the light that was transmitted after a number of reflections. 7

8 Figure 8: An illustration of how a Fabry-Pérot-interferometer works. The light is transmitted and reflected at each surface (here the reflected beams are drawn beside the original ones, to better illustrate the effect). Multiple interference gives strong transmission for some wavelengths and weak for others If the light that is transmitted through the etalon is in phase, the transmission of light will be high due to constructive interference. This will happen for waves that can fit an integer number of half wavelengths in the etalon length L. Thus, the transmittance of light through the etalon will vary periodically if the frequency of the laser light is scanned over a frequency interval. The frequency difference between two adjacent wavelengths that have high transmittance is called the free spectral range, Δf FSR, of the etalon and is calculated according Δf FSR = c 2nL where c is the speed of light and n is the refractive index of the material in the etalon. Figure 9 (and Figure 2) shows a typical transmission spectrum from a Fabry-Pérot etalon when the frequency is changed. The free spectral range is marked in the figure. Figure 9: A transmission spectrum from a Fabry-Pérot etalon as a function of frequency. Δf FSR is the difference in frequency between two adjacent peaks. 8

9 Experiments Figure 10. Set-up for laser absorption spectroscopy. 1. Set the temperature for your unit to the value given by the instructor. While you wait for it to stabilize familiarize yourself with the rest of the components and practice using the different menus on the oscilloscope: "Vertical menu", "Trigger menu", "Cursor" and "Acquire" (if you are not already an expert!). 2. Calculate the free spectral range on your Fabry-Pérot etalon. Use a plastic ruler to measure its length and that the refractive index data is 1,51118 (for etalons marked BK7) and 1,51075 (for etalons marked K8), respectively at 780 nm. 3. Connect the function generator main output to one of the channels on the oscilloscope and study the signal. Set the function generator to generate a triangular wave with about 100 Hz and 200 mv peak-to-peak amplitude. To get a stable signal on the oscilloscope screen, connect the trigger output from the function generator (SYNC OUT or AUX OUT) to the external trigger input in the oscilloscope (use "Trigger menu" to set the oscilloscope to Ext trigger). 4. When you have a triangular wave with the right frequency and amplitude, connect the function generator main output to the laser driver (MOD IN) 5. Set the driving current on the laser driver to the value given by the instructor. Warn everybody that you re going to switch on the laser. When everybody in the room has their laser goggles on you may start the laser. Warning! Diode lasers are very sensitive to transients, do not turn off power to the function generator or disconnect any cables while the diode laser is on. 6. Align the optics according to Figure 10. a. Place the filter marked ND 2 in the beam path before the gas cell to reduce its intensity by a factor 100 b. Place the Rb-cell in the beam path. Manually scan the driving current slowly around the recommended value (you can scan ± 5 ma), until you find the absorption lines. (If the oscilloscope image looks upside down, the photo detector may be connected so it gives a negative output voltage, which makes the absorption peaks look like emission peaks! To make it 9

10 more pedagogical you can use invert on on the vertical menu in the oscilloscope.) c. Use a 45 degree beam splitter (Figure 10) to send some laser light to the second photo diode, which you connect to channel 2 on the oscilloscope. d. Put in the Fabry- Pérot etalon and adjust it to obtain the interference fringes on the oscilloscope. Place a ND 1 filter between the beam splitter and lens to avoid feedback reflections from the Fabry-Pérot into the diode laser. Hint: the laser beam must be incident on the Fabry Pérot with a 90 angle 7. Hyperfine splitting and line width. Use the cursor function on the oscilloscope to determine the hyperfine splitting (the distance between the absorption peaks) and the line width (FWHM) of the absorption peaks. 8. Gas concentration. The concentration of Rb-atoms in the cell will influence the depth of the absorption peaks (higher concentration more light will be absorbed). This means that we can use the absorption spectrum to calculate the concentration of Rb-atoms in the cell a. To calculate the gas concentration from our absorption spectrum, it is absolutely necessary that the detector is working in a linear range, and that you eliminate as much background light as possible. Switch the oscilloscope vertical menu from AC to DC coupling and adjust the vertical scale until you can see the signal again. Put in more filters in the laser beam path until you are certain that there are no saturation effects, i.e. that the detector is working in a linear range. Use the 0.3 filter (dampening factor ) to check the linearity b. Calculate the linear absorption coefficient μ using the Beer-Lambert law. c. Calculate the atomic density in the cell, and compare with the value calculated in preparatory exercise 4. Use the equation on page 7. For this transition in 87 Rb λ = nm and τ = 26 ns. When calculating the statistical weights (G) we use G 2 = 2F + 1 for the resolved hyperfine states in 5s 2 S 1/2 andg 1 = 2J + 1 for the unresolved hyperfine structure in 5p 2 P 3/2. This gives us G 1 /G 2 = 4/5 for the stronger absorption peak and G 1 /G 2 = 4/3 for the weaker absorption peak. 9. Modify the set-up so that you can observe laser-induced fluorescence from the cell instead of absorption. Hint: fluorescence is another word for the spontaneous emission of light when an atom deexcites from a higher level 10

### Doppler-Free Spetroscopy of Rubidium

Doppler-Free Spetroscopy of Rubidium Pranjal Vachaspati, Sabrina Pasterski MIT Department of Physics (Dated: April 17, 2013) We present a technique for spectroscopy of rubidium that eliminates doppler

### Laser Locking with Doppler-free Saturated Absorption Spectroscopy

Laser Locking with Doppler-free Saturated Absorption Spectroscopy Paul L. Stubbs, Advisor: Irina Novikova W&M Quantum Optics Group May 12, 2010 Abstract The goal of this project was to lock the frequency

### R. J. Jones Optical Sciences OPTI 511L Fall 2017

R. J. Jones Optical Sciences OPTI 511L Fall 2017 Semiconductor Lasers (2 weeks) Semiconductor (diode) lasers are by far the most widely used lasers today. Their small size and properties of the light output

### Ph 77 ADVANCED PHYSICS LABORATORY ATOMIC AND OPTICAL PHYSICS

Ph 77 ADVANCED PHYSICS LABORATORY ATOMIC AND OPTICAL PHYSICS Diode Laser Characteristics I. BACKGROUND Beginning in the mid 1960 s, before the development of semiconductor diode lasers, physicists mostly

### Introduction Fundamentals of laser Types of lasers Semiconductor lasers

ECE 5368 Introduction Fundamentals of laser Types of lasers Semiconductor lasers Introduction Fundamentals of laser Types of lasers Semiconductor lasers How many types of lasers? Many many depending on

### A Narrow-Band Tunable Diode Laser System with Grating Feedback

A Narrow-Band Tunable Diode Laser System with Grating Feedback S.P. Spirydovich Draft Abstract The description of diode laser was presented. The tuning laser system was built and aligned. The free run

### Experimental Physics. Experiment C & D: Pulsed Laser & Dye Laser. Course: FY12. Project: The Pulsed Laser. Done by: Wael Al-Assadi & Irvin Mangwiza

Experiment C & D: Course: FY1 The Pulsed Laser Done by: Wael Al-Assadi Mangwiza 8/1/ Wael Al Assadi Mangwiza Experiment C & D : Introduction: Course: FY1 Rev. 35. Page: of 16 1// In this experiment we

### Optodevice Data Book ODE I. Rev.9 Mar Opnext Japan, Inc.

Optodevice Data Book ODE-408-001I Rev.9 Mar. 2003 Opnext Japan, Inc. Section 1 Operating Principles 1.1 Operating Principles of Laser Diodes (LDs) and Infrared Emitting Diodes (IREDs) 1.1.1 Emitting Principles

### CHAPTER 5 FINE-TUNING OF AN ECDL WITH AN INTRACAVITY LIQUID CRYSTAL ELEMENT

CHAPTER 5 FINE-TUNING OF AN ECDL WITH AN INTRACAVITY LIQUID CRYSTAL ELEMENT In this chapter, the experimental results for fine-tuning of the laser wavelength with an intracavity liquid crystal element

### Basic concepts. Optical Sources (b) Optical Sources (a) Requirements for light sources (b) Requirements for light sources (a)

Optical Sources (a) Optical Sources (b) The main light sources used with fibre optic systems are: Light-emitting diodes (LEDs) Semiconductor lasers (diode lasers) Fibre laser and other compact solid-state

### B. Cavity-Enhanced Absorption Spectroscopy (CEAS)

B. Cavity-Enhanced Absorption Spectroscopy (CEAS) CEAS is also known as ICOS (integrated cavity output spectroscopy). Developed in 1998 (Engeln et al.; O Keefe et al.) In cavity ringdown spectroscopy,

### MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Electrical Engineering and Computer Science

Student Name Date MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Electrical Engineering and Computer Science 6.161 Modern Optics Project Laboratory Laboratory Exercise No. 6 Fall 2010 Solid-State

### Lecture 6 Fiber Optical Communication Lecture 6, Slide 1

Lecture 6 Optical transmitters Photon processes in light matter interaction Lasers Lasing conditions The rate equations CW operation Modulation response Noise Light emitting diodes (LED) Power Modulation

### High-power semiconductor lasers for applications requiring GHz linewidth source

High-power semiconductor lasers for applications requiring GHz linewidth source Ivan Divliansky* a, Vadim Smirnov b, George Venus a, Alex Gourevitch a, Leonid Glebov a a CREOL/The College of Optics and

### R. J. Jones College of Optical Sciences OPTI 511L Fall 2017

R. J. Jones College of Optical Sciences OPTI 511L Fall 2017 Active Modelocking of a Helium-Neon Laser The generation of short optical pulses is important for a wide variety of applications, from time-resolved

Intensity vs λ Luminous Equivalent of Radiation When the spectral power (p(λ) for GaP-ZnO diode has a peak at 0.69µm) is combined with the eye-sensitivity curve a peak response at 0.65µm is obtained with

### FIBER OPTICS. Prof. R.K. Shevgaonkar. Department of Electrical Engineering. Indian Institute of Technology, Bombay. Lecture: 18.

FIBER OPTICS Prof. R.K. Shevgaonkar Department of Electrical Engineering Indian Institute of Technology, Bombay Lecture: 18 Optical Sources- Introduction to LASER Diodes Fiber Optics, Prof. R.K. Shevgaonkar,

### Figure 1. Schematic diagram of a Fabry-Perot laser.

Figure 1. Schematic diagram of a Fabry-Perot laser. Figure 1. Shows the structure of a typical edge-emitting laser. The dimensions of the active region are 200 m m in length, 2-10 m m lateral width and

### SECOND HARMONIC GENERATION AND Q-SWITCHING

SECOND HARMONIC GENERATION AND Q-SWITCHING INTRODUCTION In this experiment, the following learning subjects will be worked out: 1) Characteristics of a semiconductor diode laser. 2) Optical pumping on

### Temporal coherence characteristics of a superluminescent diode system with an optical feedback mechanism

VI Temporal coherence characteristics of a superluminescent diode system with an optical feedback mechanism Fang-Wen Sheu and Pei-Ling Luo Department of Applied Physics, National Chiayi University, Chiayi

### Swept Wavelength Testing:

Application Note 13 Swept Wavelength Testing: Characterizing the Tuning Linearity of Tunable Laser Sources In a swept-wavelength measurement system, the wavelength of a tunable laser source (TLS) is swept

### Spectroscopy of Ruby Fluorescence Physics Advanced Physics Lab - Summer 2018 Don Heiman, Northeastern University, 1/12/2018

1 Spectroscopy of Ruby Fluorescence Physics 3600 - Advanced Physics Lab - Summer 2018 Don Heiman, Northeastern University, 1/12/2018 I. INTRODUCTION The laser was invented in May 1960 by Theodor Maiman.

### Quantum frequency standard Priority: Filing: Grant: Publication: Description

C Quantum frequency standard Inventors: A.K.Dmitriev, M.G.Gurov, S.M.Kobtsev, A.V.Ivanenko. Priority: 2010-01-11 Filing: 2010-01-11 Grant: 2011-08-10 Publication: 2011-08-10 Description The present invention

### The Saturated Absorption Spectroscopy Lab

The Saturated Absorption Spectroscopy Lab 1 Purpose Joshua Symonds, Ian Kleckner, Brian Anderson Advanced Lab, Fall 2005 Atoms can only absorb and emit photons of very specific, quantized energies, which

### High-frequency tuning of high-powered DFB MOPA system with diffraction limited power up to 1.5W

High-frequency tuning of high-powered DFB MOPA system with diffraction limited power up to 1.5W Joachim Sacher, Richard Knispel, Sandra Stry Sacher Lasertechnik GmbH, Hannah Arendt Str. 3-7, D-3537 Marburg,

### Diode Laser Control Electronics. Diode Laser Locking and Linewidth Narrowing. Rudolf Neuhaus, Ph.D. TOPTICA Photonics AG

Appl-1012 Diode Laser Control Electronics Diode Laser Locking and Linewidth Narrowing Rudolf Neuhaus, Ph.D. TOPTICA Photonics AG Introduction Stabilized diode lasers are well established tools for many

### Multi-photon Absorption in Optical Pumping of Rubidium

Multi-photon Absorption in Optical Pumping of Rubidium Xinyi Xu (ID PIN:A51481739) Department of Physics and Astronomy Michigan State University Abstract: In optical pumping of rubidium, a new kind of

### Chapter 14. Tunable Dye Lasers. Presented by. Mokter Mahmud Chowdhury ID no.:

Chapter 14 Tunable Dye Lasers Presented by Mokter Mahmud Chowdhury ID no.:0412062246 1 Tunable Dye Lasers: - In a dye laser the active lasing medium is an organic dye dissolved in a solvent such as alcohol.

### Scintillation Counters

PHY311/312 Detectors for Nuclear and Particle Physics Dr. C.N. Booth Scintillation Counters Unlike many other particle detectors, which exploit the ionisation produced by the passage of a charged particle,

### Spectrometer using a tunable diode laser

Spectrometer using a tunable diode laser Ricardo Vasquez Department of Physics, Purdue University, West Lafayette, IN April, 2000 In the following paper the construction of a simple spectrometer using

### Kit for building your own THz Time-Domain Spectrometer

Kit for building your own THz Time-Domain Spectrometer 16/06/2016 1 Table of contents 0. Parts for the THz Kit... 3 1. Delay line... 4 2. Pulse generator and lock-in detector... 5 3. THz antennas... 6

### LEP Optical pumping

Related topics Spontaeous emission, induced emission, mean lifetime of a metastable state, relaxation, inversion, diode laser. Principle and task The visible light of a semiconductor diode laser is used

### visibility values: 1) V1=0.5 2) V2=0.9 3) V3=0.99 b) In the three cases considered, what are the values of FSR (Free Spectral Range) and

EXERCISES OF OPTICAL MEASUREMENTS BY ENRICO RANDONE AND CESARE SVELTO EXERCISE 1 A CW laser radiation (λ=2.1 µm) is delivered to a Fabry-Pérot interferometer made of 2 identical plane and parallel mirrors

### Wavelength Meter Sensitive and compact wavemeter with a large spectral range for high speed measurements of pulsed and continuous lasers.

Wavelength Meter Sensitive and compact wavemeter with a large spectral range for high speed measurements of pulsed and continuous lasers. Unrivaled precision Fizeau based interferometers The sturdiness

### Nd:YSO resonator array Transmission spectrum (a. u.) Supplementary Figure 1. An array of nano-beam resonators fabricated in Nd:YSO.

a Nd:YSO resonator array µm Transmission spectrum (a. u.) b 4 F3/2-4I9/2 25 2 5 5 875 88 λ(nm) 885 Supplementary Figure. An array of nano-beam resonators fabricated in Nd:YSO. (a) Scanning electron microscope

### PHY 451: Advanced Laboratory Manual for Diode Laser Spectroscopy. Derek Neben, Lennart Dabelow

PHY 451: Advanced Laboratory Manual for Diode Laser Spectroscopy Derek Neben, Lennart Dabelow Department of Physics & Astronomy Michigan State University East Lansing, MI 48824 Motivation The general idea

### ECE 340 Lecture 29 : LEDs and Lasers Class Outline:

ECE 340 Lecture 29 : LEDs and Lasers Class Outline: Light Emitting Diodes Lasers Semiconductor Lasers Things you should know when you leave Key Questions What is an LED and how does it work? How does a

### VCSEL Based Optical Sensors

VCSEL Based Optical Sensors Jim Guenter and Jim Tatum Honeywell VCSEL Products 830 E. Arapaho Road, Richardson, TX 75081 (972) 470 4271 (972) 470 4504 (FAX) Jim.Guenter@Honeywell.com Jim.Tatum@Honeywell.com

### Chapter 8. Wavelength-Division Multiplexing (WDM) Part II: Amplifiers

Chapter 8 Wavelength-Division Multiplexing (WDM) Part II: Amplifiers Introduction Traditionally, when setting up an optical link, one formulates a power budget and adds repeaters when the path loss exceeds

### Wavelength Control and Locking with Sub-MHz Precision

Wavelength Control and Locking with Sub-MHz Precision A PZT actuator on one of the resonator mirrors enables the Verdi output wavelength to be rapidly tuned over a range of several GHz or tightly locked

### Observational Astronomy

Observational Astronomy Instruments The telescope- instruments combination forms a tightly coupled system: Telescope = collecting photons and forming an image Instruments = registering and analyzing the

### Key Questions. What is an LED and how does it work? How does a laser work? How does a semiconductor laser work? ECE 340 Lecture 29 : LEDs and Lasers

Things you should know when you leave Key Questions ECE 340 Lecture 29 : LEDs and Class Outline: What is an LED and how does it How does a laser How does a semiconductor laser How do light emitting diodes

### Midterm #1 Prep. Revision: 2018/01/20. Professor M. Csele, Niagara College

Midterm #1 Prep Revision: 2018/01/20 Professor M. Csele, Niagara College Portions of this presentation are Copyright John Wiley & Sons, 2004 Review Material Safety Finding MPE for a laser Calculating OD

### Ultraviolet Visible Infrared Instrumentation

Ultraviolet Visible Infrared Instrumentation Focus our attention on measurements in the UV-vis region of the EM spectrum Good instrumentation available Very widely used techniques Longstanding and proven

### Lecture 21. Wind Lidar (3) Direct Detection Doppler Lidar

Lecture 21. Wind Lidar (3) Direct Detection Doppler Lidar Overview of Direct Detection Doppler Lidar (DDL) Resonance fluorescence DDL Fringe imaging DDL Scanning FPI DDL FPI edge-filter DDL Absorption

### Zeeman Shifted Modulation Transfer Spectroscopy in Atomic Cesium

Zeeman Shifted Modulation Transfer Spectroscopy in Atomic Cesium Modulation transfer spectroscopy (MTS) is a useful technique for locking a laser on one of the closed cesium D transitions. We have focused

### UNMATCHED OUTPUT POWER AND TUNING RANGE

ARGOS MODEL 2400 SF SERIES TUNABLE SINGLE-FREQUENCY MID-INFRARED SPECTROSCOPIC SOURCE UNMATCHED OUTPUT POWER AND TUNING RANGE One of Lockheed Martin s innovative laser solutions, Argos TM Model 2400 is

### Chapter 1 Introduction

Chapter 1 Introduction 1-1 Preface Telecommunication lasers have evolved substantially since the introduction of the early AlGaAs-based semiconductor lasers in the late 1970s suitable for transmitting

### Measurement of the Speed of Light in Air

(revised, 2/27/01) Measurement of the Speed of Light in Air Advanced Laboratory, Physics 407 University of Wisconsin Madison, WI 53706 Abstract The speed of light is determined from a time of flight measurement

### COMPONENTS OF OPTICAL INSTRUMENTS. Chapter 7 UV, Visible and IR Instruments

COMPONENTS OF OPTICAL INSTRUMENTS Chapter 7 UV, Visible and IR Instruments 1 Topics A. GENERAL DESIGNS B. SOURCES C. WAVELENGTH SELECTORS D. SAMPLE CONTAINERS E. RADIATION TRANSDUCERS F. SIGNAL PROCESSORS

### COMPONENTS OF OPTICAL INSTRUMENTS. Topics

COMPONENTS OF OPTICAL INSTRUMENTS Chapter 7 UV, Visible and IR Instruments Topics A. GENERAL DESIGNS B. SOURCES C. WAVELENGTH SELECTORS D. SAMPLE CONTAINERS E. RADIATION TRANSDUCERS F. SIGNAL PROCESSORS

### University of Washington INT REU Final Report. Construction of a Lithium Photoassociation Laser

University of Washington INT REU Final Report Construction of a Lithium Photoassociation Laser Ryne T. Saxe The University of Alabama, Tuscaloosa, AL Since the advent of laser cooling and the demonstration

### Semiconductor Optical Communication Components and Devices Lecture 18: Introduction to Diode Lasers - I

Semiconductor Optical Communication Components and Devices Lecture 18: Introduction to Diode Lasers - I Prof. Utpal Das Professor, Department of lectrical ngineering, Laser Technology Program, Indian Institute

### Lecture 18: Photodetectors

Lecture 18: Photodetectors Contents 1 Introduction 1 2 Photodetector principle 2 3 Photoconductor 4 4 Photodiodes 6 4.1 Heterojunction photodiode.................... 8 4.2 Metal-semiconductor photodiode................

BLACKBODY RADIATION PHYSICS 359E INTRODUCTION In this laboratory, you will make measurements intended to illustrate the Stefan-Boltzmann Law for the total radiated power per unit area I tot (in W m 2 )

### IST IP NOBEL "Next generation Optical network for Broadband European Leadership"

DBR Tunable Lasers A variation of the DFB laser is the distributed Bragg reflector (DBR) laser. It operates in a similar manner except that the grating, instead of being etched into the gain medium, is

### Universal and compact laser stabilization electronics

top-of-fringe LaseLock LaseLock Universal and compact laser stabilization electronics Compact, stand-alone locking electronics for diode lasers, dye lasers, Ti:Sa lasers, or optical resonators Side-of-fringe

### Photoassociative Spectroscopy of Strontium Along the 1 S 0-3 P 1. Transition using a Littman/Metcalf Laser. Andrew Traverso. T.C.

Photoassociative Spectroscopy of Strontium Along the 1 S 0-3 P 1 Transition using a Littman/Metcalf Laser By Andrew Traverso Advisor: T.C. Killian Abstract We present the design and implementation of an

### Instytut Fizyki Doświadczalnej Wydział Matematyki, Fizyki i Informatyki UNIWERSYTET GDAŃSKI

Instytut Fizyki Doświadczalnej Wydział Matematyki, Fizyki i Informatyki UNIWERSYTET GDAŃSKI I. Background theory. 1. The temporal and spatial coherence of light. 2. Interaction of electromagnetic waves

### SA210-Series Scanning Fabry Perot Interferometer

435 Route 206 P.O. Box 366 PH. 973-579-7227 Newton, NJ 07860-0366 FAX 973-300-3600 www.thorlabs.com technicalsupport@thorlabs.com SA210-Series Scanning Fabry Perot Interferometer DESCRIPTION: The SA210

### Review of Semiconductor Physics

Review of Semiconductor Physics k B 1.38 u 10 23 JK -1 a) Energy level diagrams showing the excitation of an electron from the valence band to the conduction band. The resultant free electron can freely

### Fabry-Perot Cavity FP1-A INSTRUCTOR S MANUAL

Fabry-Perot Cavity FP1-A INSTRUCTOR S MANUAL A PRODUCT OF TEACHSPIN, INC. TeachSpin, Inc. 2495 Main Street Suite 409 Buffalo, NY 14214-2153 Phone: (716) 885-4701 Fax: (716) 836-1077 WWW.TeachSpin.com TeachSpin

### A continuous-wave Raman silicon laser

A continuous-wave Raman silicon laser Haisheng Rong, Richard Jones,.. - Intel Corporation Ultrafast Terahertz nanoelectronics Lab Jae-seok Kim 1 Contents 1. Abstract 2. Background I. Raman scattering II.

### CHAPTER 7. Components of Optical Instruments

CHAPTER 7 Components of Optical Instruments From: Principles of Instrumental Analysis, 6 th Edition, Holler, Skoog and Crouch. CMY 383 Dr Tim Laurens NB Optical in this case refers not only to the visible

### Period 3 Solutions: Electromagnetic Waves Radiant Energy II

Period 3 Solutions: Electromagnetic Waves Radiant Energy II 3.1 Applications of the Quantum Model of Radiant Energy 1) Photon Absorption and Emission 12/29/04 The diagrams below illustrate an atomic nucleus

### Introduction to the operating principles of the HyperFine spectrometer

Introduction to the operating principles of the HyperFine spectrometer LightMachinery Inc., 80 Colonnade Road North, Ottawa ON Canada A spectrometer is an optical instrument designed to split light into

### Optical cesium beam clock for eprtc telecom applications

Optical cesium beam clock for eprtc telecom applications Michaud Alain, Director R&D and PLM Time & Frequency, Oscilloquartz Dr. Patrick Berthoud, Chief Scientist Time & Frequency, Oscilloquartz Workshop

### Understanding Optical Communications

Understanding Optical Communications Harry J. R. Dutton International Technical Support Organization http://www.redbooks.ibm.com SG24-5230-00 International Technical Support Organization Understanding

### PERFORMANCE OF PHOTODIGM S DBR SEMICONDUCTOR LASERS FOR PICOSECOND AND NANOSECOND PULSING APPLICATIONS

PERFORMANCE OF PHOTODIGM S DBR SEMICONDUCTOR LASERS FOR PICOSECOND AND NANOSECOND PULSING APPLICATIONS By Jason O Daniel, Ph.D. TABLE OF CONTENTS 1. Introduction...1 2. Pulse Measurements for Pulse Widths

### Study of Multiwavelength Fiber Laser in a Highly Nonlinear Fiber

Study of Multiwavelength Fiber Laser in a Highly Nonlinear Fiber I. H. M. Nadzar 1 and N. A.Awang 1* 1 Faculty of Science, Technology and Human Development, Universiti Tun Hussein Onn Malaysia, Johor,

### LASER DIODE MODULATION AND NOISE

> 5' O ft I o Vi LASER DIODE MODULATION AND NOISE K. Petermann lnstitutfiir Hochfrequenztechnik, Technische Universitdt Berlin Kluwer Academic Publishers i Dordrecht / Boston / London KTK Scientific Publishers

### Light for Ultra Cold Molecules Final Report for PHYS349

Light for Ultra Cold Molecules Final Report for PHYS349 Friedrich Kirchner April 28, 2006 In this final report, I will describe some of the work I did as part of my project in Kirk Madison s lab. The report

### Vertical External Cavity Surface Emitting Laser

Chapter 4 Optical-pumped Vertical External Cavity Surface Emitting Laser The booming laser techniques named VECSEL combine the flexibility of semiconductor band structure and advantages of solid-state

### Spectroscopy Lab 2. Reading Your text books. Look under spectra, spectrometer, diffraction.

1 Spectroscopy Lab 2 Reading Your text books. Look under spectra, spectrometer, diffraction. Consult Sargent Welch Spectrum Charts on wall of lab. Note that only the most prominent wavelengths are displayed

### FFP-C Fiber Fabry-Perot Controller OPERATING INSTRUCTIONS. Version 1.0 MICRON OPTICS, INC.

FFP-C Fiber Fabry-Perot Controller OPERATING INSTRUCTIONS Version 1.0 MICRON OPTICS, INC. 1852 Century Place NE Atlanta, GA 30345 USA Tel (404) 325-0005 Fax (404) 325-4082 www.micronoptics.com Page 2 Table

### Frequency evaluation of collimated blue light generated by wave mixing in Rb vapour

Frequency evaluation of collimated blue light generated by wave mixing in Rb vapour Alexander Akulshin 1, Christopher Perrella 2, Gar-Wing Truong 2, Russell McLean 1 and Andre Luiten 2,3 1 Centre for Atom

### Exercise 8: Interference and diffraction

Physics 223 Name: Exercise 8: Interference and diffraction 1. In a two-slit Young s interference experiment, the aperture (the mask with the two slits) to screen distance is 2.0 m, and a red light of wavelength

### Elimination of Self-Pulsations in Dual-Clad, Ytterbium-Doped Fiber Lasers

Elimination of Self-Pulsations in Dual-Clad, Ytterbium-Doped Fiber Lasers 1.0 Modulation depth 0.8 0.6 0.4 0.2 0.0 Laser 3 Laser 2 Laser 4 2 3 4 5 6 7 8 Absorbed pump power (W) Laser 1 W. Guan and J. R.

### Chapter 3 OPTICAL SOURCES AND DETECTORS

Chapter 3 OPTICAL SOURCES AND DETECTORS 3. Optical sources and Detectors 3.1 Introduction: The success of light wave communications and optical fiber sensors is due to the result of two technological breakthroughs.

### Developing an Electronically Controlled External Cavity Diode Laser System for use in Atomic Spectroscopy

McNair Scholars Research Journal Volume 10 Issue 1 Article 4 2017 Developing an Electronically Controlled External Cavity Diode Laser System for use in Atomic Spectroscopy Samuel C. Carano scarano@emich.edu

### White Paper Laser Sources For Optical Transceivers. Giacomo Losio ProLabs Head of Technology

White Paper Laser Sources For Optical Transceivers Giacomo Losio ProLabs Head of Technology September 2014 Laser Sources For Optical Transceivers Optical transceivers use different semiconductor laser

### 레이저의주파수안정화방법및그응용 박상언 ( 한국표준과학연구원, 길이시간센터 )

레이저의주파수안정화방법및그응용 박상언 ( 한국표준과학연구원, 길이시간센터 ) Contents Frequency references Frequency locking methods Basic principle of loop filter Example of lock box circuits Quantifying frequency stability Applications

### SPRAY DROPLET SIZE MEASUREMENT

SPRAY DROPLET SIZE MEASUREMENT In this study, the PDA was used to characterize diesel and different blends of palm biofuel spray. The PDA is state of the art apparatus that needs no calibration. It is

### Dual-channel Lock-in Amplifier Module

Dual-channel Lock-in Amplifier Module Introduction Phase-locked amplification and demodulation techniques of weak signals have a wide range of applications in Turnable Diode Laser Absorption Spectrum (TDLAS)

### A novel tunable diode laser using volume holographic gratings

A novel tunable diode laser using volume holographic gratings Christophe Moser *, Lawrence Ho and Frank Havermeyer Ondax, Inc. 85 E. Duarte Road, Monrovia, CA 9116, USA ABSTRACT We have developed a self-aligned

### Construction and Characterization of a Prototype External Cavity Diode Laser

Construction and Characterization of a Prototype External Cavity Diode Laser Joshua Wienands February 8, 2011 1 1 Introduction 1.1 Laser Cooling Cooling atoms with lasers is achieved through radiation

### Lecture 5: Introduction to Lasers

Lecture 5: Introduction to Lasers http://en.wikipedia.org/wiki/laser History of the Laser v Invented in 1958 by Charles Townes (Nobel prize in Physics 1964) and Arthur Schawlow of Bell Laboratories v Was

### Characterization and Development of an Extended Cavity Tunable Laser Diode

San Jose State University SJSU ScholarWorks Master's Theses Master's Theses and Graduate Research Spring 2014 Characterization and Development of an Extended Cavity Tunable Laser Diode Fnu Traptilisa San

### Examination Optoelectronic Communication Technology. April 11, Name: Student ID number: OCT1 1: OCT 2: OCT 3: OCT 4: Total: Grade:

Examination Optoelectronic Communication Technology April, 26 Name: Student ID number: OCT : OCT 2: OCT 3: OCT 4: Total: Grade: Declaration of Consent I hereby agree to have my exam results published on

### New Developments in TDLAS NH3 Monitoring

New Developments in TDLAS NH3 Monitoring Presented by John Pisano CEMTEK Environmental UCR (University of California at Riverside) Unisearch Associates Inc Outline What is a tunable diode laser (TDL) The

### [4] (b) Fig. 6.1 shows a loudspeaker fixed near the end of a tube of length 0.6 m. tube m 0.4 m 0.6 m. Fig. 6.

1 (a) Describe, in terms of vibrations, the difference between a longitudinal and a transverse wave. Give one example of each wave.................... [4] (b) Fig. 6.1 shows a loudspeaker fixed near the

### Observation of Rb Two-Photon Absorption Directly Excited by an. Erbium-Fiber-Laser-Based Optical Frequency. Comb via Spectral Control

Observation of Rb Two-Photon Absorption Directly Excited by an Erbium-Fiber-Laser-Based Optical Frequency Comb via Spectral Control Jiutao Wu 1, Dong Hou 1, Xiaoliang Dai 2, Zhengyu Qin 2, Zhigang Zhang

### NORTHWESTERN UNIVERSITY MULTI-SPECTRAL RAMAN GAIN IN DUAL-ISOTOPE RUBIDIUM VAPOR A THESIS SUBMITTED TO THE GRADUATE SCHOOL

NORTHWESTERN UNIVERSITY MULTI-SPECTRAL RAMAN GAIN IN DUAL-ISOTOPE RUBIDIUM VAPOR A THESIS SUBMITTED TO THE GRADUATE SCHOOL IN PARTIAL FULFILLMENT OF THE REQUIREMENTS for the degree MASTER OF SCIENCE Field

### VCSELs With Enhanced Single-Mode Power and Stabilized Polarization for Oxygen Sensing

VCSELs With Enhanced Single-Mode Power and Stabilized Polarization for Oxygen Sensing Fernando Rinaldi and Johannes Michael Ostermann Vertical-cavity surface-emitting lasers (VCSELs) with single-mode,

### Chemistry 524--"Hour Exam"--Keiderling Mar. 19, pm SES

Chemistry 524--"Hour Exam"--Keiderling Mar. 19, 2013 -- 2-4 pm -- 170 SES Please answer all questions in the answer book provided. Calculators, rulers, pens and pencils permitted. No open books allowed.

### Powerful Single-Frequency Laser System based on a Cu-laser pumped Dye Laser

Powerful Single-Frequency Laser System based on a Cu-laser pumped Dye Laser V.I.Baraulya, S.M.Kobtsev, S.V.Kukarin, V.B.Sorokin Novosibirsk State University Pirogova 2, Novosibirsk, 630090, Russia ABSTRACT

### Advanced Features of InfraTec Pyroelectric Detectors

1 Basics and Application of Variable Color Products The key element of InfraTec s variable color products is a silicon micro machined tunable narrow bandpass filter, which is fully integrated inside the

### Nd: YAG Laser Energy Levels 4 level laser Optical transitions from Ground to many upper levels Strong absorber in the yellow range None radiative to

Nd: YAG Lasers Dope Neodynmium (Nd) into material (~1%) Most common Yttrium Aluminum Garnet - YAG: Y 3 Al 5 O 12 Hard brittle but good heat flow for cooling Next common is Yttrium Lithium Fluoride: YLF