Basic concepts. Optical Sources (b) Optical Sources (a) Requirements for light sources (b) Requirements for light sources (a)
|
|
- Hugh Clarke
- 6 years ago
- Views:
Transcription
1 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 lasers are used in some systems Semiconductor laser diodes Standard HeNe lasers LED Fibre laser Blue solid-state lasers Requirements for light sources (a) Sufficient output power Overcome component losses Laser (mw range) has much higher power than LED (W range) Narrow spectral linewidth Minimizes fiber dispersion and increases transmission capacity in WDM systems Laser has much narrower linewidth (typically 13 nm) than LED (typically 3050 nm) The spectral linewidth depends on device structure Directional light output Increases coupling efficiency Laser (spreading at an angle of 10-0 ) couples more light into fiber than LED (spreading out at larger angles) Requirements for light sources (b) Useful emission wavelength region For low fiber attenuation and small fiber dispersion. (typical windows: nm, 1300 nm, 1550 nm) Emission wavelength depends on semiconductor material from which the light source is made Requirements for light sources (c) Modulation Easily modulated at high bit rates» greater information capacity Speed. Lasers are faster than LEDs Stable light output Cheap and reliable Basic concepts LASER: Light Amplification by Stimulated Emission of Radiation Absorption: Atom excited to higher energy state (i.e. E 1 E ) when bombarded by photon with energy hf 1
2 Spontaneous emission Photon with energy hf is released when atom moves from higher to lower energy state emits light in random directions and out of phase» Incoherent radiation» Mechanism for light generation in LEDs Stimulated emission Photon with energy hf forces atom to return to lower energy state, and generates second photon also with energy hf. Stimulating and stimulated photons have same energy hf (hence same frequency f) and are in phase (hence same polarization)» Coherent radiation» Optical amplification» Mechanism for light generation in lasers Extrinsic semiconductors Group V impurities (e.g. P) Possess five valence electrons Leaves an excess electron for every impurity atom» Known as n-type semiconductor Group III impurities (e.g. B) Possess three valence electrons Each atom covalently bonds with 3 host atoms Constitute an excess hole for every impurity atom» Known as p-type semiconductor The p-n junction A p-n junction is fabricated from a single slice of semiconductor, with one side doped p-type and the other n-type In trying to neutralize charges Free electrons in n-type diffuse across junction to p-type Free holes in p-type diffuse to n-type Electrons & holes close to junction recombine A depletion region (free of mobile charge carriers) establishes a potential barrier between the p and n type regions which restricts the inter-diffusion of majority carriers from their respective regions in the absence of an externally applied voltage LED - Spontaneous emission (a) When the junction is forward biased, both the depletion region width and the resulting potential barrier are reduced Electrons from the n type region and holes from the p type region can flow more readily across the junction into the opposite type region The increased concentration of minority carriers in the opposite type region in the forward biased p-n diode leads to the recombination of carriers across the bandgap LED - Spontaneous emission (b) In band to band radiative recombination the energy is released with the creation of a photon, the energy of which is given by E g hf
3 LED (Light Emitting Diode) Structures of optical sources To achieve a high radiance and a high quantum efficiency Carrier confinement: achieve a high level of radiative recombination in the active region of the device, which yields a high quantum efficiency Optical confinement: prevent absorption of the emitted radiation by the material surrounding the pn junction Homojunctions and single and double heterojunctions have been widely investigated a semiconductor p-n junction, the materials on either side of which are formed by doping the same basic starting material, such junctions are termed homojunctions A heterojunction consists of two adjoining semiconductor materials with different band-gap energies Homojunction stucture (a) Homojunction structure (b) Single heterojunction structure (a) Single heterojunction structure (b) The electrons injected from the n GaAs layer (1) to the p GaAs active layer () are blocked from diffusing over a large distance by the potential barrier provided by the higher-bandgap p AlGaAs layer (3) The active thickness is therefore determined by the thickness of the p-gaas region. For small d, a smaller drive current can give the same carrier density. Thus power efficiency is higher than the homojunction laser The lower refractive index of the AlGaAs layer provides improved optical confinement (only on one side of the active region) 3
4 Double heterojunction structure (a) Double heterojunction structure (b) A layer of GaAs is sandwiched between two layers of the compound GaAlAs which has a wider energy gap than GaAs and also a lower refractive index The carrier and optical confinement may be achieved simultaneously The bandgap differences from potential barriers in both the conduction and valence bands which prevent electrons and holes injected into the GaAs layer from diffusing away The step change in refractive index provides a very much more efficient waveguide structure than was the case in homojunction lasers and the radiation is confined mainly to the active region LED sources LEDs and Lasers Have similar light generating structures Main differences LED:» current density is low» spontaneous emission Laser:» Large current density» Population inversion» Optical feedback resonance» Stimulated emission Laser Basic Operation LASER: Light Amplification by Stimulated Emission of Radiation LASER = Optical oscillator Need a feedback path Need a gain medium to overcome the losses in the light path Need something to start the oscillation Fabry-Perot cavity (1) Consider two mirrors with given reflectivity creating a cavity filled with a passive material of refractive index n If light is injected, the transmission will depend on the reflectivity of each mirror and the wavelength of the light. L n R 1 R 4
5 Fabry-Perot cavity () L Laser Diode n R 1 R Standing wave (resonance of the cavity) exists when: nl i i The separation between two consecutive resonances is: c f nl This cavity acts as a multi-frequency filter Fabry-Perot cavity (3) Resonant Frequencies The cavity can also be seen as an optical feedback loop (part of the light bounces on the mirrors) What happen if the passive material in the cavity is replaced by an active material? L gain R 1 R n Simplified spectra How can we make the gain material and then start the oscillator? f Wavelength output of a FPC (Fabry-Perot Cavity) laser defined by the combination of the gain curve and the axial modes of the cavity Worst case full range linewidth Laser Basic Operation Worst case linewidth: the difference in wavelength between the worst extreme axial modes; i.e. 5 as shown in the figure below The worst case estimate of the pulse spreading by dispersion Stimulated emission 5
6 The Einstein Relations In thermal equilibrium, the population of the two energy levels of a system described by Boltzmann statistics is: N1 g1 exp( E1 / KT ) g1 exp[( E E1) / KT ] N g exp( E / KT ) g g1 exp( hf / KT ) (11) g where N 1 and N represent the density of atoms in energy levels E 1 and E, respectively, with g 1 and g being the corresponding degeneracies of the levels, K is Boltzmann s constant and T is the absolute temperature Under the condition of thermal equilibrium, the lower energy level E 1 of the two level atomic system contains more atoms than the upper energy level E Population inversion (a) To achieve optical amplification it is necessary to create a nonequilibrium distribution of atoms such that the population of the upper level is greater than that of the lower energy level. The condition is known as population inversion Populations in a two energy level system: (a) Boltzmann distribution for a system in thermal equilibrium; (b) a nonequilibrium distribution showing population inversion Population inversion (b) Optical feedback and laser oscillation (a) Population inversion may be obtained at a p-n junction by heavy doping (degenerative doping) of both the p and n type material by passing a high drive current through the diode, which results in the majority charge carriers to excite to a higher energy level The radiation in the laser diode is generated within a Fabry- Perot resonator cavity, as in most other types of lasers Optical feedback and laser oscillation (b) The mirror facets are constructed by making two parallel clefts along natural cleavage planes of the semiconductor crystal The mirrors provide strong optical feedback in the longitudinal direction, thereby converting the device into an oscillator with a gain mechanism that compensates for optical losses in the cavity The device will oscillate (thereby emitting light) at those resonant frequencies for which the gain is sufficient to overcome the losses The sides of the cavity are simply formed by roughening the edges of the device to reduce unwanted emissions in these directions Comparison of LED and laser diode characteristics Optical output power against drive current Radiant output as a function of frequency for a p-n junction laser: (a) below threshold (spontaneous emission); (b) with the laser modes at threshold; and (c) with the dominant laser mode above threshold 6
7 Experimental demonstration (a) Experimental demonstration (b) Power (µw) LED Current (ma) Power (µw) Laser Diode Current (ma) Example 6 (a) Question 4: A GaAs laser operating at 850 nm has a 500 µm length and a refractive index n = 3.7. What are the frequency and wavelength spacings. Example 6 (b) Solution: 8 c 310 f 81.1GHz -6 Ln Ln nm 3.7 Example 7 (a) A particular semiconductor FPC laser is fabricated using active material with a bandgap of 1.3x10-19 J and a refractive index of The cavity length is 75m and it is possible for 7 axial modes to operate under the gain curve. What is the full width worst case linewidth? Example 7 (b) Solution: Estimate the operating wavelength: 6 hc / Eg m 1. 53m max Use max to calculate the axial mode spacing 6 ( ) / Ln 1nm Hence if 7 modes can operate the worse case linewidth is 6nm. 7
8 Multimode laser diode Laser Fabry-Perot ST package Fabry-Perot laser diode Single mode lasers To obtain single-mode operation it is necessary to eliminate all but one of the longitudinal modes Reduce the length L of the cavity until the frequency separation of the adjacent modes is larger than the laser transition linewidth or gain curve Distributed feedback based lasers: the use of distributed resonators, fabricated into the laser structure to give integrated wavelength selectivity Laser - Distributed Feedback (DFB) Feedback in a DFB laser is provided by a series of periodic perturbations built into the structure along the length of the gain medium and sufficiently close to the active region to interact with the evanescent field 0 is the vacuum wavelength and 0 /n is the wavelength in the material: 0 = nd Butterfly package DFB laser diode Laser Vertical Cavity Surface Emitting Lasers (VCSELs) Laser Distributed Bragg Reflector (DBR) Lasers A Bragg grating is printed into a portion of the semiconductor The Bragg grating will reflect one wavelength depending on the period of the grating. Only one mode at the Bragg wavelength will lase. Bragg section 00µm Phase section 130µm Active section 790µm InP p InP n ion implantation Active section Phase section Bragg section Alcatel-Thales 8
9 Comparison Coupling to a fibre (a) Coupling to a fibre (b) Use of a Graded Index Lens (GRIN lens). The lens collects and focuses the light onto the end of the fibre (a) Use a ball lens. An epoxy resin bonds the lens to the surface of the LED, however the refractive index (RI) of the epoxy cannot match to both the RI of the fibre (~1.45) and the RI of the semiconductor (~3.5) (b) Direct coupling. Mount the LED inside a connector and the fibre is mounted in the other half of the connector. Low cost and low complexity (c) Fix a ball lens to the end of a fibre (d) Laser safety (1) Laser light is very dangerous and should be treated as a significant hazard Lasers are classified by hazard potential based upon their optical emission. Necessary control measures are determined by these classifications. In the U.S., laser classifications are based on American National Standards Institute s (ANSI) Z136.1 Safe Use of Lasers. Laser safety (): laser classes and hazards Lasers are grouped according to the degree of hazard Classes 1, and 3a are safe for viewing because of limited power and irradiance Classes 3b and 4 require appropriate precautions to be taken Most medical devices are Classes 3b or 4 and require eye protection and detailed training Laser safety (3): laser ANSI classification Class 1 denotes laser or laser systems that do not, under normal operating conditions, pose a hazard Class denotes low-power visible lasers or laser system which, because of the normal human aversion response (i.e., blinking, eye movement, etc.), do not normally present a hazard, but may present some potential for hazard if viewed directly for extended periods of time (like many conventional light sources). Class 3a denotes some lasers or laser systems having a CAUTION label that normally would not injure the eye if viewed for only momentary periods (within the aversion response period) with the unaided eye, but may present a greater hazard if viewed using collecting optics. Class 3a lasers have DANGER labels and are capable of exceeding permissible exposure levels. If operated with care Class 3a lasers pose a low risk of injury. 9
10 Laser safety (4): laser ANSI classification Class 3b denotes lasers or laser systems that can produce a hazard it viewed directly. This includes intrabeam viewing of specular reflections. Normally, Class 3b lasers will not produce a hazardous diffuse reflection. Class 4 denotes lasers and laser systems that produce a hazard not only from direct or specular reflections, but may also produce significant skin hazards as well as fire hazards. 10
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
More informationOptodevice 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
More informationLecture 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
More informationFigure 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
More informationLuminous Equivalent of Radiation
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
More informationECE 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
More informationKey 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
More informationIntroduction 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
More informationSemiconductor 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
More informationChapter 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.
More informationMAHALAKSHMI ENGINEERING COLLEGE TIRUCHIRAPALLI
MAHALAKSHMI ENGINEERING COLLEGE TIRUCHIRAPALLI - 621213 DEPARTMENT : ECE SUBJECT NAME : OPTICAL COMMUNICATION & NETWORKS SUBJECT CODE : EC 2402 UNIT III: SOURCES AND DETECTORS PART -A (2 Marks) 1. What
More informationSemiconductor Lasers Semiconductors were originally pumped by lasers or e-beams First diode types developed in 1962: Create a pn junction in
Semiconductor Lasers Semiconductors were originally pumped by lasers or e-beams First diode types developed in 1962: Create a pn junction in semiconductor material Pumped now with high current density
More informationOptical MEMS in Compound Semiconductors Advanced Engineering Materials, Cal Poly, SLO November 16, 2007
Optical MEMS in Compound Semiconductors Advanced Engineering Materials, Cal Poly, SLO November 16, 2007 Outline Brief Motivation Optical Processes in Semiconductors Reflectors and Optical Cavities Diode
More informationPhotonics and Fiber Optics
1 UNIT V Photonics and Fiber Optics Part-A 1. What is laser? LASER is the acronym for Light Amplification by Stimulated Emission of Radiation. The absorption and emission of light by materials has been
More informationUNIT-III SOURCES AND DETECTORS. According to the shape of the band gap as a function of the momentum, semiconductors are classified as
UNIT-III SOURCES AND DETECTORS DIRECT AND INDIRECT BAND GAP SEMICONDUCTORS: According to the shape of the band gap as a function of the momentum, semiconductors are classified as 1. Direct band gap semiconductors
More informationSemiconductor Lasers Semiconductors were originally pumped by lasers or e-beams First diode types developed in 1962: Create a pn junction in
Semiconductor Lasers Semiconductors were originally pumped by lasers or e-beams First diode types developed in 1962: Create a pn junction in semiconductor material Pumped now with high current density
More informationWhite 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
More informationOptical Sources and Detectors
Optical Sources and Detectors 1. Optical Sources Optical transmitter coverts electrical input signal into corresponding optical signal. The optical signal is then launched into the fiber. Optical source
More informationUNIT What is splicing? Explain about fusion splicing? Ans: Splicing
UNIT 4 1. What is splicing? Explain about fusion splicing? Ans: Splicing A permanent joint formed between two individual optical fibers in the field is known as splicing. The fiber splicing is used to
More informationLecture 4 Fiber Optical Communication Lecture 4, Slide 1
Lecture 4 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
More informationPh 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
More informationLaser Diode. Photonic Network By Dr. M H Zaidi
Laser Diode Light emitters are a key element in any fiber optic system. This component converts the electrical signal into a corresponding light signal that can be injected into the fiber. The light emitter
More informationCONTENTS. 2.2 Schrodinger's Wave Equation 31. PART I Semiconductor Material Properties. 2.3 Applications of Schrodinger's Wave Equation 34
CONTENTS Preface x Prologue Semiconductors and the Integrated Circuit xvii PART I Semiconductor Material Properties CHAPTER 1 The Crystal Structure of Solids 1 1.0 Preview 1 1.1 Semiconductor Materials
More informationFIBER 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,
More informationLight Sources, Modulation, Transmitters and Receivers
Optical Fibres and Telecommunications Light Sources, Modulation, Transmitters and Receivers Introduction Previous section looked at Fibres. How is light generated in the first place? How is light modulated?
More informationOptoelectronics ELEC-E3210
Optoelectronics ELEC-E3210 Lecture 4 Spring 2016 Outline 1 Lateral confinement: index and gain guiding 2 Surface emitting lasers 3 DFB, DBR, and C3 lasers 4 Quantum well lasers 5 Mode locking P. Bhattacharya:
More informationChapter 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
More informationTECHNICAL BRIEF O K I L A S E R D I O D E P R O D U C T S. OKI Laser Diodes
TECHNICAL BRIEF O K I L A S E R D I O D E P R O D U C T S OKI Laser Diodes June 1995 OKI Laser Diodes INTRODUCTION This technical brief presents an overview of OKI laser diode and edge emitting light emitting
More informationVERTICAL CAVITY SURFACE EMITTING LASER
VERTICAL CAVITY SURFACE EMITTING LASER Nandhavel International University Bremen 1/14 Outline Laser action, optical cavity (Fabry Perot, DBR and DBF) What is VCSEL? How does VCSEL work? How is it different
More informationBN 1000 May Profile Optische Systeme GmbH Gauss Str. 11 D Karlsfeld / Germany. Tel Fax
BN 1000 May 2000 Profile Optische Systeme GmbH Gauss Str. 11 D - 85757 Karlsfeld / Germany Tel + 49 8131 5956-0 Fax + 49 8131 5956-99 info@profile-optsys.com www.profile-optsys.com Profile Inc. 87 Hibernia
More informationChapter 4 O t p ica c l a So S u o r u ce c s
Chapter 4 Optical Sources Contents Review of Semiconductor Physics Light Emitting Diode (LED) - Structure, Material,Quantum efficiency, LED Power, Modulation Laser Diodes - structure, Modes, Rate Equation,Quantum
More informationS Optical Networks Course Lecture 2: Essential Building Blocks
S-72.3340 Optical Networks Course Lecture 2: Essential Building Blocks Edward Mutafungwa Communications Laboratory, Helsinki University of Technology, P. O. Box 2300, FIN-02015 TKK, Finland Tel: +358 9
More informationLecture 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................
More informationCONTENTS. Chapter 1 Wave Nature of Light 19
CONTENTS Chapter 1 Wave Nature of Light 19 1.1 Light Waves in a Homogeneous Medium 19 A. Plane Electromagnetic Wave 19 B. Maxwell's Wave Equation and Diverging Waves 22 Example 1.1.1 A diverging laser
More informationR. 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
More informationSafa O. Kasap Electrical Engineering Department, University of Saskatchewan, Saskatoon, S7N 5A9, Canada
1 Optoelectronics Safa O. Kasap Electrical Engineering Department, University of Saskatchewan, Saskatoon, S7N 5A9, Canada e-mail: kasap@engr.usask.ca Abstract It is useful to view today s optoelectronics
More informationFundamentals of Laser
SMR 1826-3 Preparatory School to the Winter College on Fibre 5-9 February 2007 Fundamentals of Laser Imrana Ashraf Zahid Quaid-i-Azam University Islamabad Pakistan Fundamentals of Laser Dr. Imrana Ashraf
More informationCHAPTER 8 The PN Junction Diode
CHAPTER 8 The PN Junction Diode Consider the process by which the potential barrier of a PN junction is lowered when a forward bias voltage is applied, so holes and electrons can flow across the junction
More informationOptoelectronics EE/OPE 451, OPT 444 Fall 2009 Section 1: T/Th 9:30-10:55 PM
Optoelectronics EE/OPE 451, OPT 444 Fall 009 Section 1: T/Th 9:30-10:55 PM John D. Williams, Ph.D. Department of Electrical and Computer Engineering 406 Optics Building - UAHuntsville, Huntsville, AL 35899
More informationNEW YORK CITY COLLEGE of TECHNOLOGY
NEW YORK CITY COLLEGE of TECHNOLOGY THE CITY UNIVERSITY OF NEW YORK DEPARTMENT OF ELECTRICAL AND TELECOMMUNICATIONS ENGINEERING TECHNOLOGY Course : TCET 4102 (TC 700) Fiber-optic communications Module
More informationDoppler-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
More informationLEDs, Photodetectors and Solar Cells
LEDs, Photodetectors and Solar Cells Chapter 7 (Parker) ELEC 424 John Peeples Why the Interest in Photons? Answer: Momentum and Radiation High electrical current density destroys minute polysilicon and
More informationLecture 9 External Modulators and Detectors
Optical Fibres and Telecommunications Lecture 9 External Modulators and Detectors Introduction Where are we? A look at some real laser diodes. External modulators Mach-Zender Electro-absorption modulators
More informationFunctional Materials. Optoelectronic devices
Functional Materials Lecture 2: Optoelectronic materials and devices (inorganic). Photonic materials Optoelectronic devices Light-emitting diode (LED) displays Photodiode and Solar cell Photoconductive
More informationMAJOR REQUIREMENTS OPTICAL FIBER EMITTER
MAJOR REQUIREMENTS OPTICAL FIBER EMITTER 1. LIGHT 0/P SHOULD BE HIGHLY DIRECTIONAL. 2. SOURCE SHOULD BE LINEAR (MIN. DISTORTION AND NOISE) 3. SHOULD EMIT LIGHT AT WAVELENGTHS WHERE THE FIBER HAS LOW LOSSES
More informationOptical Amplifiers. Continued. Photonic Network By Dr. M H Zaidi
Optical Amplifiers Continued EDFA Multi Stage Designs 1st Active Stage Co-pumped 2nd Active Stage Counter-pumped Input Signal Er 3+ Doped Fiber Er 3+ Doped Fiber Output Signal Optical Isolator Optical
More informationLASER 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
More informationAbsorption: in an OF, the loss of Optical power, resulting from conversion of that power into heat.
Absorption: in an OF, the loss of Optical power, resulting from conversion of that power into heat. Scattering: The changes in direction of light confined within an OF, occurring due to imperfection in
More informationExamination 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
More informationOptical Fibers p. 1 Basic Concepts p. 1 Step-Index Fibers p. 2 Graded-Index Fibers p. 4 Design and Fabrication p. 6 Silica Fibers p.
Preface p. xiii Optical Fibers p. 1 Basic Concepts p. 1 Step-Index Fibers p. 2 Graded-Index Fibers p. 4 Design and Fabrication p. 6 Silica Fibers p. 6 Plastic Optical Fibers p. 9 Microstructure Optical
More informationElements of Optical Networking
Bruckner Elements of Optical Networking Basics and practice of optical data communication With 217 Figures, 13 Tables and 93 Exercises Translated by Patricia Joliet VIEWEG+ TEUBNER VII Content Preface
More informationLecture 2 p-n junction Diode characteristics. By Asst. Prof Dr. Jassim K. Hmood
Electronic I Lecture 2 p-n junction Diode characteristics By Asst. Prof Dr. Jassim K. Hmood THE p-n JUNCTION DIODE The pn junction diode is formed by fabrication of a p-type semiconductor region in intimate
More informationIST 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
More informationCHAPTER 8 The PN Junction Diode
CHAPTER 8 The PN Junction Diode Consider the process by which the potential barrier of a PN junction is lowered when a forward bias voltage is applied, so holes and electrons can flow across the junction
More informationChapter 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
More informationPhysics of Waveguide Photodetectors with Integrated Amplification
Physics of Waveguide Photodetectors with Integrated Amplification J. Piprek, D. Lasaosa, D. Pasquariello, and J. E. Bowers Electrical and Computer Engineering Department University of California, Santa
More informationOptical Sources & Detectors for Fiber Optic communication
Optical Sources & Detectors for Fiber Optic communication JK Chhabra EX Scientist, CSIO, Chandigarh Professor ECE JIET Jind Consultants Professor IIIT Allahabad chhabra_ jk@yahoo.com The Nobel Prize in
More informationCopyright 2006 Crosslight Software Inc. Analysis of Resonant-Cavity Light-Emitting Diodes
Copyright 2006 Crosslight Software Inc. www.crosslight.com 1 Analysis of Resonant-Cavity Light-Emitting Diodes Contents About RCLED. Crosslight s model. Example of an InGaAs/AlGaAs RCLED with experimental
More informationLAB V. LIGHT EMITTING DIODES
LAB V. LIGHT EMITTING DIODES 1. OBJECTIVE In this lab you are to measure I-V characteristics of Infrared (IR), Red and Blue light emitting diodes (LEDs). The emission intensity as a function of the diode
More informationIntroduction to Optoelectronic Devices
Introduction to Optoelectronic Devices Dr. Jing Bai Assistant Professor Department of Electrical and Computer Engineering University of Minnesota Duluth October 30th, 2012 1 Outline What is the optoelectronics?
More informationUnderstanding 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
More informationProblem 4 Consider a GaAs p-n + junction LED with the following parameters at 300 K: Electron diusion coecient, D n = 25 cm 2 =s Hole diusion coecient
Prof. Jasprit Singh Fall 2001 EECS 320 Homework 7 This homework is due on November 8. Problem 1 An optical power density of 1W/cm 2 is incident on a GaAs sample. The photon energy is 2.0 ev and there is
More informationImplant Confined 1850nm VCSELs
Implant Confined 1850nm VCSELs Matthew M. Dummer *, Klein Johnson, Mary Hibbs-Brenner, William K. Hogan Vixar, 2950 Xenium Ln. N. Plymouth MN 55441 ABSTRACT Vixar has recently developed VCSELs at 1850nm,
More informationUNIT-II : SIGNAL DEGRADATION IN OPTICAL FIBERS
UNIT-II : SIGNAL DEGRADATION IN OPTICAL FIBERS The Signal Transmitting through the fiber is degraded by two mechanisms. i) Attenuation ii) Dispersion Both are important to determine the transmission characteristics
More informationDIODE LASER SPECTROSCOPY (160309)
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
More informationElectronic devices-i. Difference between conductors, insulators and semiconductors
Electronic devices-i Semiconductor Devices is one of the important and easy units in class XII CBSE Physics syllabus. It is easy to understand and learn. Generally the questions asked are simple. The unit
More informationInP-based Waveguide Photodetector with Integrated Photon Multiplication
InP-based Waveguide Photodetector with Integrated Photon Multiplication D.Pasquariello,J.Piprek,D.Lasaosa,andJ.E.Bowers Electrical and Computer Engineering Department University of California, Santa Barbara,
More informationOptical Communication and Networks M.N. Bandyopadhyay
Optical Communication and Networks M.N. Bandyopadhyay Director National Institute of Technology (NIT) Calicut Delhi-110092 2014 OPTICAL COMMUNICATION AND NETWORKS M.N. Bandyopadhyay 2014 by PHI Learning
More informationSt. Joseph s College of Arts & Science (Autonomous) Cuddalore PG & RESEARCH DEPARTMENT OF PHYSICS SUBJECT : LASER & FIBER OPTICCOMMUNICATION
St. Joseph s College of Arts & Science (Autonomous) Cuddalore 607001 PG & RESEARCH DEPARTMENT OF PHYSICS SUBJECT : LASER & FIBER OPTICCOMMUNICATION SUBJECT CODE: PH612S SUBJECT INCHARGE: Mr. M.Sathish
More informationLAB V. LIGHT EMITTING DIODES
LAB V. LIGHT EMITTING DIODES 1. OBJECTIVE In this lab you will measure the I-V characteristics of Infrared (IR), Red and Blue light emitting diodes (LEDs). Using a photodetector, the emission intensity
More informationOptical Amplifiers Photonics and Integrated Optics (ELEC-E3240) Zhipei Sun Photonics Group Department of Micro- and Nanosciences Aalto University
Photonics Group Department of Micro- and Nanosciences Aalto University Optical Amplifiers Photonics and Integrated Optics (ELEC-E3240) Zhipei Sun Last Lecture Topics Course introduction Ray optics & optical
More informationLongitudinal Multimode Dynamics in Monolithically Integrated Master Oscillator Power Amplifiers
Longitudinal Multimode Dynamics in Monolithically Integrated Master Oscillator Power Amplifiers Antonio PEREZ-SERRANO (1), Mariafernanda VILERA (1), Julien JAVALOYES (2), Jose Manuel G. TIJERO (1), Ignacio
More informationCOMPONENTS 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
More informationCOMPONENTS 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
More informationTemporal 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
More informationLecture 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
More informationFiberoptic Communication Systems By Dr. M H Zaidi. Optical Amplifiers
Optical Amplifiers Optical Amplifiers Optical signal propagating in fiber suffers attenuation Optical power level of a signal must be periodically conditioned Optical amplifiers are a key component in
More informationPHYSICAL ELECTRONICS(ECE3540) APPLICATIONS OF PHYSICAL ELECTRONICS PART I
PHYSICAL ELECTRONICS(ECE3540) APPLICATIONS OF PHYSICAL ELECTRONICS PART I Tennessee Technological University Monday, October 28, 2013 1 Introduction In the following slides, we will discuss the summary
More informationVertical 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
More informationRobert G. Hunsperger. Integrated Optics. Theory and Technology. Sixth Edition. 4ü Spri rineer g<
Robert G. Hunsperger Integrated Optics Theory and Technology Sixth Edition 4ü Spri rineer g< 1 Introduction 1 1.1 Advantages of Integrated Optics 2 1.1.1 Comparison of Optical Fibers with Other Interconnectors
More informationTapered Amplifiers. For Amplification of Seed Sources or for External Cavity Laser Setups. 750 nm to 1070 nm COHERENT.COM DILAS.
Tapered Amplifiers For Amplification of Seed Sources or for External Cavity Laser Setups 750 nm to 1070 nm COHERENT.COM DILAS.COM Welcome DILAS Semiconductor is now part of Coherent Inc. With operations
More informationLASER Transmitters 1 OBJECTIVE 2 PRE-LAB
LASER Transmitters 1 OBJECTIVE Investigate the L-I curves and spectrum of a FP Laser and observe the effects of different cavity characteristics. Learn to perform parameter sweeps in OptiSystem. 2 PRE-LAB
More informationOptical Communications and Networking 朱祖勍. Oct. 9, 2017
Optical Communications and Networking Oct. 9, 2017 1 Optical Amplifiers In optical communication systems, the optical signal from the transmitter are attenuated by the fiber and other passive components
More informationBa 14: Solid State Laser Principles I
- Ba 14.1 - Ba 14: Solid State Laser Principles I 1. Abstract The process of light amplification by stimulated emission of radiation (laser) can currently provide electromagnetic radiation with exceptional
More informationVCSELs and Optical Interconnects
VCSELs and Optical Interconnects Anders Larsson Chalmers University of Technology ADOPT Winter School on Optics and Photonics February 4-7, 6 Outline Part VCSEL basics - Physics and design - Static and
More informationSemiconductor Devices
Semiconductor Devices Modelling and Technology Source Electrons Gate Holes Drain Insulator Nandita DasGupta Amitava DasGupta SEMICONDUCTOR DEVICES Modelling and Technology NANDITA DASGUPTA Professor Department
More informationCavity QED with quantum dots in semiconductor microcavities
Cavity QED with quantum dots in semiconductor microcavities M. T. Rakher*, S. Strauf, Y. Choi, N.G. Stolz, K.J. Hennessey, H. Kim, A. Badolato, L.A. Coldren, E.L. Hu, P.M. Petroff, D. Bouwmeester University
More information15 Transit Time and Tunnel NDR Devices
15 Transit Time and Tunnel NDR Devices Schematics of Transit-time NDR diode. A packet of carriers (e.g., electrons) is generated in a confined and narrow zone (generation region) and injected into the
More informationLecture 4 INTEGRATED PHOTONICS
Lecture 4 INTEGRATED PHOTONICS What is photonics? Photonic applications use the photon in the same way that electronic applications use the electron. Devices that run on light have a number of advantages
More informationUniversità degli Studi di Roma Tor Vergata Dipartimento di Ingegneria Elettronica. Analogue Electronics. Paolo Colantonio A.A.
Università degli Studi di Roma Tor Vergata Dipartimento di Ingegneria Elettronica Analogue Electronics Paolo Colantonio A.A. 2015-16 Introduction: materials Conductors e.g. copper or aluminum have a cloud
More informationWavelength 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
More information1 Semiconductor-Photon Interaction
1 SEMICONDUCTOR-PHOTON INTERACTION 1 1 Semiconductor-Photon Interaction Absorption: photo-detectors, solar cells, radiation sensors. Radiative transitions: light emitting diodes, displays. Stimulated emission:
More information21. (i) Briefly explain the evolution of fiber optic system (ii) Compare the configuration of different types of fibers. or 22. (b)(i) Derive modal eq
Unit-1 Part-A FATIMA MICHAEL COLLEGE OF ENGINEERING & TECHNOLOGY Senkottai Village, Madurai Sivagangai Main Road, Madurai - 625 020. [An ISO 9001:2008 Certified Institution] DEPARTMENT OF ELECTRONICS AND
More informationMode analysis of Oxide-Confined VCSELs using near-far field approaches
Annual report 998, Dept. of Optoelectronics, University of Ulm Mode analysis of Oxide-Confined VCSELs using near-far field approaches Safwat William Zaki Mahmoud We analyze the transverse mode structure
More informationTutorial. Various Types of Laser Diodes. Low-Power Laser Diodes
371 Introduction In the past fifteen years, the commercial and industrial use of laser diodes has dramatically increased with some common applications such as barcode scanning and fiber optic communications.
More informationAdvanced semiconductor lasers
Advanced semiconductor lasers Quantum cascade lasers Single mode lasers DFBs, VCSELs, etc. Quantum cascade laser Reminder: Semiconductor laser diodes Conventional semiconductor laser CB diode laser: material
More informationRECENTLY, studies have begun that are designed to meet
838 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 43, NO. 9, SEPTEMBER 2007 Design of a Fiber Bragg Grating External Cavity Diode Laser to Realize Mode-Hop Isolation Toshiya Sato Abstract Recently, a unique
More informationSpatial Investigation of Transverse Mode Turn-On Dynamics in VCSELs
Spatial Investigation of Transverse Mode Turn-On Dynamics in VCSELs Safwat W.Z. Mahmoud Data transmission experiments with single-mode as well as multimode 85 nm VCSELs are carried out from a near-field
More informationIntroduction Fundamental of optical amplifiers Types of optical amplifiers
ECE 6323 Introduction Fundamental of optical amplifiers Types of optical amplifiers Erbium-doped fiber amplifiers Semiconductor optical amplifier Others: stimulated Raman, optical parametric Advanced application:
More informationChapter 12: Optical Amplifiers: Erbium Doped Fiber Amplifiers (EDFAs)
Chapter 12: Optical Amplifiers: Erbium Doped Fiber Amplifiers (EDFAs) Prof. Dr. Yaocheng SHI ( 时尧成 ) yaocheng@zju.edu.cn http://mypage.zju.edu.cn/yaocheng 1 Traditional Optical Communication System Loss
More information