Planar External Cavity Low Noise Narrow Linewidth Lasers Lew Stolpner Redfern Integrated Optics Inc. Santa Clara, CA 95054, USA 1
Outline 1550 nm narrow linewidth lasers for fiber optic sensing Planar External Cavity PLANEX Laser Design Phase noise and linewidth reduction in the external cavity PLANEX phase noise and linewidth Wavelength and power stability Wavelength tunability Direct frequency modulation Direct power modulation/pulsing Phase locking RIO laser products 2
Optical Sensing and Metrology Military/security Perimeter intrusion detection Navy acoustic detection Interferometric Coherent Rayleigh Applications Sensing Technologies C-OTDR Oil and Gas Seismic Reservoir Monitoring Down well and SAGD Pipeline Intrusion and Leakage Detection Avionics/Space LIDAR RFOG Wind Metrology Wind energy Air traffic control Coherent Doppler LIDAR Lasers Low Noise Narrow Linewidth Photonic Doppler Velocimetry /Vibrometery Brillouin DTSS BOTDA/R Structural Monitoring Static strain detection Dynamic strain/vibration detection R&D/ Industrial/ Military, metrology and process control 3
Laser for Sensing: Key Requirements Optical sensing market challenges for laser business Market size it relatively small Requirements vary significantly for various sensing technologies Critical to make laser source suitable for multiple applications Performance 1550 nm wavelength range to utilize availability of other Telco solutions Low Phase/ Frequency Noise, Narrow linewidth, low RIN Features Small size, suitable for large multi-laser system integration Frequency modulation and wavelength tunability Field deployable Stability in harsh environmental conditions Reliability qualification to industry standards (Telcordia, MIL, Space) 4
Planar External Cavity Laser PLANEX TM Gain Chip PLC TEC Bragg Grating PLC with Bragg grating on silicon wafers Gain: optimized InP MQW chip Packaging: 14-pin butterfly package, proven processes and materials PLANEX ORION 5
PLANEX TM Laser Phase Noise Phase Noise (urad/sqrt(hz)-m) Phase Noise Comparison 100.00 RIO PLANEX FL-O FL-K 10.00 1.00 0.10 1 10 100 1000 10000 100000 Frequency (Hz) 6
Linewidth Measurement vs. Spectral Integration Frequency Noise (Hz/sqrt(Hz)) SDH Beat Spectrum (db) ORION Laser Frequency Noise 10000 1000 100 10 White noise level 1 1 10 100 1000 10000 100000 1000000 Frequency (Hz) Integration 5 0-5 -10-15 -20-25 -30-35 Laser Linewidth SDH Beat Spectrum -40-250 -200-150 -100-50 0 50 100 150 200 250 Frequency (khz) SDH measurement Spectral integration Spectral integration: white noise only Observation time on SI: 30 msec. SI for white noise only is done with fiber delay 400 km. Both measurement and spectral integration match well down to -40 db level on Linewidth (LW) spectrum. (LW ~ 2.7 khz @ -20 db) When only white noise level is integrated, SI provides pure Lorentzian LW ~ 1.2 khz. 7
RIN (db/hz) RIN (db/hz) PLANEX RIN Shot noise limited up to 5GHz -100 RIN 100 khz - 20 GHz -100 RIN 100 Hz 100 khz -110-110 -120-120 -130-140 -150-130 -140-150 -160-170 -180 0 5,000 10,000 15,000 20,000 Frequency (MHz) -160-170 -180 100 1,000 10,000 100,000 Frequency (Hz) High frequencies of relaxation oscillations Electron Photon resonance Photon-photon resonance (cavity round-trip) RIN < 140 db/hz at frequency > 2 khz. Shot noise limited up to 5 GHz 8
Excess Noise Lorentzian linewidth as a parameter is not sufficient for RIO developed special test to provide all information for Doppler metrology applications Excess noise < 0.2 db for RIO laser with Lorentzian linewidth of 1.6 khz RIO ORION laser 61.3 db 9
Power and Wavelength Stability Tested w. 10 mw ORION laser ORION laser is stabilized in thermal chamber over 3 days ORION case reaches near const. case temp. after 30 min. of power-up Pk-Pk wavelength change over 3 days: 0.6 pm (NOTE: measured with Agilent 86122A WM, WL differential accuracy: +/- 0.4 pm) Pk-Pk output power change over 3 days: 0.19 mw (NOTE: measured with Agilent 86122A WM, P calibration accuracy: +/- 0.5 db) 10
Frequency Stability Test ORION lasers modules (free running) frequency stability measured with heterodyne mixing of two lasers Laser stabilization time <1 s after turn on or re-tuning 11
ORION Laser Module Frequency Stability Measurement Time Frequency stability 50 msec 150 khz p-p 30 sec 1.5 MHz p-p 1 hour 4 MHz p-p 12 hours 20 MHz p-p 12
ORION Laser Allan Deviation Allan Deviation_Noramalized 1.0E-06 1.0E-07 Fiber Laser ORION (G4) beating 1.0E-08 1.0E-09 ORION (G3) ORION (G4) beating ref. 1.0E-10 0.1 1.0 10.0 100.0 1,000.0 10,000.0 100,000.0 Observation Time (sec.) Free-running. Case temperature stabilized : <0.2 o C over 3 h 13
Wavelength (nm) Wavelength, nm Wavelength Tunability Wavelength vs. TEC temperature: ~15 pm/ºc Wavelength vs. bias current, CW: 0.4-0.5 pm/ma (40-60 MHz/mA) 1551.000 1550.950 1550.900 1550.850 1550.800 18 19 20 21 22 23 Ts (C) Wavelength vs. Bias Current 1543.580 1543.579 1543.578 1543.577 1543.576 1543.575 1543.574 1543.573 1543.572 1543.571 1543.570 90 95 100 105 110 115 120 Bias Current, ma Phase continuous temperature tuning range ± 30 pm (± 4 GHz) Fast wavelength tuning via bias current up to 4 pm (500 MHz) Frequency tuning via bias current leads to simultaneous power modulation 14
Wavelength Tuning and Direct FM WL tuning (pm) D Phase Noise (db) FM sensitivity MHz/V, fa/va Tuning TEC Temperature and Bias Current Slow thermal tuning up to +/- 30 pm (+/- 4 GHz) Fast direct frequency modulation efficiency CW : 0.9 MHz/mV (~ 50 MHz/mA) 10 khz: 0.5MHz/mV 35.00 1.4 30.00 1.2 25.00 1.0 20.00 0.8 15.00 0.6 10.00 0.4 5.00 0.2 0.00 0.0-5.00-0.2-10.00-0.4-15.00-0.6-20.00-0.8 WL tuning_measured -25.00-1.0-30.00 Delta Phase Noise -1.2-35.00-1.4-8 -3 2 7 21.6 C, 22.4 C, 23.2 C, 24 C, 24.8 C, 25.6C, 26.8 C, 147 ma 139 ma 131 ma 123 ma 115 ma 107 ma 95 ma 0 Set point 200 180 160 140 120 100 80 60 40 20 DM Modulation Electronic FM Thermal FM 0.01 0.1 1 10 100 Frequency, MHz 15
Frequency Noise [Hz/sqrt(Hz)] Low Frequency Noise with DM-FM 100000 Frequency Noise Measurements (MI at quadrature), Modulation: Sine-wave, Modulation frequency fm = 1 MHz, Input 100 mvpp 10000 1000 100 10 1 1 10 100 1,000 10,000 100,000 1,000,000 10,000,000 Frequency (Hz) 16
Frequency noise [Hz/rtHz] Reference Locking 10 8 10 7 10 6 10 5 10 4 10 3 10 2 10 1 Free-running Locked to acetylene 10 0 10-4 10-3 10-2 10-1 10 0 10 1 10 2 10 3 10 4 10 5 Frequency [Hz] Frequency noise spectrum of the PLANEX laser with (blue) and without (red) frequency stabilization. Within the control bandwidth of ~60 Hz, the noise was suppressed by a factor up to ~1000. Performance of planar-waveguide external cavity laser for precision measurements. Kenji Numata, Jordan Camp, Michael A. Krainak, and Lew Stolpner. October 2010 / Vol. 18, No. 22 / OPTICS EXPRESS 17
PLANEX- PLANEX FM Gain Chip PLC Waveguide AR EOM Chip Gain Chip PLC HR AR AR Waveguide Bragg Grating Lens H R AR Parameter PLANEX PLANEX FM Cavity 2 sections GC + WBG PLC 3 sections GC+ WBG PLC + LN FM FM Modulation Direct bias current 1. Direct bias current 2. LN FM voltage Residual AM Coupled with FM Practically decoupled with FM FM frequency > 100 MHz Not flat with phase reverse >50 MHz bulk LN FM >1 GHz with WG Flat phase possible 18
Direct Modulation/Pulsing of PLANEX laser PLANEX laser modulation bandwidth > 1 GHz 25 Ohms impedance input Unique direct modulation/pulsing while mountings narrow linewidth performance Minimal pulse shape distortion Pulse Width Pulse Repetition Frequency Extinction Ratio Linewidth Pulse shape distortion RMS Jitter > 5 nsec up to 10 MHz 25-32 db < 15 khz at pulse plateau Minimum or none 150 ps max 19
Phase Noise, urad/sqrt(hz) 1 m OPD RIO Product Offering Wavelength ITU DWDM or custom wavelength 4 Grades of linewidth/phase noise performance PMF and SMF options PLANEX and ORION > 10 mw > 20 mw 1000 100 10 Typical Phase Noise Gr 1 Gr 2 Gr 3 Gr4 RIO COLORADO Wide tunable 1 1 10 100 1000 Frequency, Hz RIO Grande >1 W > 2 W Optical Phase Locked Loop (OPLL) Linewidth, khz Grade 1 Grade 2 Grade 3 Grade 4 Optional <15 <10 <5 <3 1 20
ORION Laser Features Low noise current source and TEC controller Input for direct modulation and wavelength tuning OEM Module with SPI, RS-232 and RS-485 interface options, GUI Benchtop OEM Source with USB interface options, GUI Storage Temp, º C -40 to +85 Size, mm 100x56x13 Operational Temp Range, ºC 0-70 Power supply Power Dissipation, @ 35 C case temperature @ 50 C case temperature 5 V < 6 W <3 W <4 W 21
ORION and Fiber Laser Comparison RIO008X ORION Koheras Basik NP Photonics Rock Orbits Ethernal Parameter Power >10 mw >10 mw >25mW >10 mw RIN WL stability (FR), p-p <-140 db/hz (>1 khz) 4 MHz 1 hour 20 MHz 12 h <-115 db/hz (@1 MHz) 20 MHz 1 h <-110 db/hz (@1 MHz) 20 MHz 1 h 50 MHz, 12 h -120 db/hz (@ 1MHz) 20 MHz 1 h Storage Temp, º C -40 to +85-20 to +50-20 to +50-20 to +50 Size, inches 4x2.25x0.5 8x4x1 8x5x1 7x3X1 Operational Temp Range, ºC 0-70 15-50 15-35 10-55 Power supply 5 V 12 V 5V 5V Power Dissipation, over specified case temp range < 6 W >10 W 20 W >10 W @ 35 C case temperature <3 W 20 W @ 50 C case temperature <4 W >10 W 22
RIN (db/hz) Phase noise (mrad/sqrt(hz)) Frequency noise (Hz/sqrt(Hz)) RIO GRANDE: Amplified High Power Modules Power 0.1 W up to 2 W, Low phase noise Ultra low RIN Narrow linewidth High OSNR -120.0-130.0-140.0 1000.0 100.0 RIO GRANDE 9110515 ORION 800094 G1 G2 G3 G4 10000 1000-150.0 10.0-160.0 100 1.0-170.0 10-180.0 0 10,000 20,000 30,000 40,000 50,000 Frequency (khz) 0.1 1 10 100 1000 10000 100000 Frequency (Hz) 23
Normalized linew idth spectrum (db) RIO COLORADO Wide Tunable Laser Performance Highlights Low frequency noise Low RIN Available for C or L spectral bands Cost effective solution Convenience: GUI, integration High Wavelength Stability (HWS) Mode Narrow linewidth <100 khz Optical Power Adjustment from 4 to 28 mw Continuous Wavelength Sweep: 24 GHz peakpeak or +/- 12 GHz) at any wavelength Amplitude Modulation to 1MHz, M up to 10% Ultra-Narrow Linewidth (UNL) Mode Ultra narrow linewidth ~ 25 khz Fixed wavelength and optical power Frequency Modulation is available Popt = 20 mw, Lorentzian Linewidth 22 khz 5 0-5 -10-15 -20-25 -30-35 -40-45 -50-2,500-1,500-500 500 1,500 2,500 Frequency (khz) 24
OPLL - Dual Laser Source OPLL for distributed sensing and coherent metrology applications: Distributed Brillouin Fiber Optic Sensing (BOTDA/BOTDR) Heterodyne/ Coherent Metrology 25
OPLL Key Performance Specs and Features Parameter Value Note CW power > 5 mw average, two PM optical outputs Laser frequency noise 10 3 Hz/ Hz @ 100 Hz under locking conditions: Linewidth <10 khz Phase noise -65 db/hz at 100 khz offset Frequency offset From 8 to 14 GHz step tuning Tuning resolution 10 khz Continuous sweep tuning over 1GHz resolution 10 khz @ 50msec speed Locked step response time 5 msec at 10 MHz step 26
Wavelength Change (pm) Exceptional Reliability for Space Applications Space qualification Defined by NASA as Game changing laser for unique combination of high performance and outstanding reliability for space applications Selected by ESA and NASA for several space programs: PROBA-3, GRACE FO, LISA and successfully completed Phase 1 of qualification testing Reliability testing for space qualification Environmental stress far exceeding Telcordia and MIL requirements Tested production PLANEX units without special builds/selection/screening Minimal changes after 1000 operating temperature cycles in vacuum and over 500 severe non-operational temperature cycles Wavelength Change in Temp cycling (-40 C to 85 C) 40 35 30 25 20 15 10 5 0 0 100 200 300 400 500 600 Cycles 100785 101033 101039 101132 101142 101163 101168 101248 101285 101550 101597 Limit 27
Thank you. 28