PHOTLINE Technologies LiNbO3 Modulators MMIC Amplifiers Instrumentations Hervé Gouraud November 2009
Pulsed modulation Fiber Lasers Pulse generation Pulse picking Pulse shaping
Extinction Ratio (ER) / Contrast Modulator choice Extinction ratio applies only to intensity modulators, and characterizes the efficiency of the modulator to Transmit in ON state and broke light when in OFF state. OFF state ON state ON state MAX At the MIN point, all the light is diffracted out, no light will be guided by the output optical fiber. P opt ER 1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 Vπ 1 At the MAX point, all the input power (mins Insertion Loss) will be transmitted to the output fiber. Optical Output V Applied Voltage -5-4 -3-2 -1 MIN OFF state 0,2 0,1 0 MIN 0 1 2 3 4 5 LiNb0 3 intensity modulators are Mach-Zehnder waveguide interferometers, whose transfer function is a sine curve. Modulation Curve Linear scale Optical Signal For Pulse application, - working point is fixed at the MIN (MBC necessity), - applied pulse are modulation voltage equal Vπ (driver necessity). MIN Point Electrical Signal
Extinction Ratio / Contrast Modulator choice Modulation Curve 1129-05 1550 nm Log scale Relative transmitted Optical Power (db) 10 0-10 -20-30 -40 ON state Extinction ratio Value -50-12 -10-8 -6-4 -2 0 2 4 6 8 OFF state Voltage DC electrodes (Volt) The 1060 NIR-MX-LN is the leader for high Extinction Ratio value Models available with associated ER values: NIR-MX-LN-10/20 > 30 db typ Option High Extinction Ratio: NIR-MX-LN-10/20 > 33dB Option Very High Extinction Ratio: NIR-MX-LN-10/20 > 36 db Option NIR-DSM-MX-LN Very High Extinction Ratio > 50 db The 1550 MXPE-LN is the leader for high Extinction Ratio value Models available with associated ER values: MXPE-LN-10/20 > 30 db typ Option High Extinction Ratio: MXPE-LN-10/20 > 33dB Option Very High Extinction Ratio: MXPE-LN-10/20 > 36 db Option Extra High Extinction Ratio: MXPE-LN-10/20 > 40 db
Modulator Bias Controller MBC is a bias controller specially designed to stabilize the operating point of LiNb0 3 Mach-Zehnder modulators by monitoring the bias voltage applied on the DC electrodes of the devices. MBC is absolutely necessary for pulse application. MBC A Mach-Zehnder modulator is illuminated by a laser at the optical input. The pulse-datas are applied to the RF electrodes. At the output of the MZ modulator, a fiber coupler with a strong imbalance (10:90 or 1:99) allows to detect a small portion of the transmitted light with a monitoring photodiode. The signal is amplified and processed in order to control the stability of the operating point. Any deviation is compensated by a new value of the electrical bias voltage applied by the feedback loop in order to maintain the operating point at the desired position. MBC controllers lock any modulators at the MIN point of its transfer function.
1 DR-PL-10-LR/HR : dedicated amplifier for Pulse application The DR-PL-10 is a modulator driver for pulse application, factory optimized to fit with end user repetition rate and pulse width. 0,9 0,8 0,7 0,6 Vπ 1 0,5 0,4 0,3 Pulse width P opt 0,2 0,1-5 -4-3 -2-1 MIN 0 0 Repetition Rate RF Driver boosts the electrical input signal (coming from Pulse generator or TTL signal). The Driver is recommended in order to: - reach Vπ amplitude and get modulator ER, - guaranty stabilized input modulator voltage whatever the FRR and PW generated from the Pulse generator. - compensate pulse distortion involved by the modulator (and reach very square pulse shape). V RF Input Repetition Rate Repetition Rate Pulse width Vπ Pulse width Photline Drivers: DR-PL-10 or DR-PL-20
Pulsed Generation Set-up 1520nm 1580nm: MXPE-LN-10 MXPE-LN-20 980nm-1150nm: NIR-MX-LN-10 NIR-MX-LN-20 780nm-850nm: NIR-MX800-LN-10 NIR-MX800-LN-20 780nm 2200 nm High Extinction Ratio Modulator CW DFB DR-PL-10 DR-PL-20 MBC-1001 To generate pulses from an optical continuous wave laser To generate low rise / fall time with short pulses Application: industrial lasers
Pulsed Shaping Set-up 1520nm 1580nm: MXPE-LN-10 MXPE-LN-20 980nm-1150nm: NIR-MX-LN-10 NIR-MX-LN-20 780nm-850nm: NIR-MX800-LN-10 NIR-MX800-LN-20 Shorten Pulses Shaping Pulse (Lorentzian, Gaussian, arbitrary shape) DR-PL-10 DR-PL-20 MBC-1001 To shorten pulses from an optical pulse train with low rise / fall times To reshape pulses (Lorentzian, Gaussian, arbitrary shapes) from an optical pulse train Application: industrial lasers
Pulsed picking Set-up 1520nm 1580nm: MXPE-LN-10 MXPE-LN-20 980nm-1150nm: NIR-MX-LN-10 NIR-MX-LN-20 780nm-850nm: NIR-MX800-LN-10 NIR-MX800-LN-20 DR-PL-10 DR-PL-20 To select one pulse among a burst of optical pulses from a pulsed fiber laser High extinction ratio required when a cascade of optical amplifier is introduced at the output Application: industrial lasers
1129-05 1550 nm Pulse Modulation Intensity Modulators & Drivers MXPE 1520-1580 nm ER: 35-50 db CW In Pw: 500 mw Relative transmitted Optical Power (db) 10 0-10 -20-30 -40 Log scale NIR-MX-LN 980-1150 nm ER:30-40 db CW In Pw: 100 mw Modulation Curve OFF state ON state NIR-MX800-LN 780-850 nm ER: 20-30 db CW In Pw: 10 mw Extinction ratio Value up to 50 db DR-PL-10/20 Pulse driver Driver will fit the Pulse specifications (Pulse width & Repetition Rate) -50-12 -10-8 -6-4 -2 0 2 4 6 8 Voltage DC electrodes (Volt) NIR-DSM-MX-LN 980-1150 nm ER: > 50 db CW In Pw: 100 mw > 50 db Rise / Fall time < 25 ps 20 % 80 % DSM: Double Stage Modulator
Modulator Bias Controller MBC-Board MBC-1001 MBC-PD-1001 MBC-WDM MBC-Board: Customized Pre-programmed OEM electronic board MBC-1001: Benchtop version, pre-set and manual bias point. MBC-PD-1001: Customized Pre-programmed OEM electronic board MBC-WDM: Up to 5 modulators bias controlled (up to 20 with the 19" version) MBC controllers are dither signal based : a small amplitude, low frequency tone signal is superimposed to the modulation signal. The resulting optical modulation is then detected and a digital signal processing based on a FFT analysis principle allows to lock the operating point at the desired position.
Pulsed generation ModBox RS 232 PM Pulse Generation Unit Modulator High Extinction ratio MBC-Board PM FC/APC DC in DC PM External Photodiode Coupler PM 1/99 %, 5/95 % The ModBox Integrates 1 High Extinction Ratio Modulator 1 Pulse driver 1 MBC (Min point) Option 790 nm 2200 nm DFB Laser Photodiode Driver DR-PL-10/20 RF in Main Optical Input FC/APC - PM Gain control Pulse RF Input SMA Main Optical Output FC/APC - PM
Sub-nanosecond pulses - Example In 1 ns Out 1 ns Out 1 ns In 100 ps Out 100 ps Rise / Fall time 30 ps Rise / Fall time 40 ps
DELIVERING MODULATION SOLUTIONS