The Theta Laser A Low Noise Chirped Pulse Laser. Dimitrios Mandridis

Transcription

1 CREOL Affiliates Day 2011 The Theta Laser A Low Noise Chirped Pulse Laser Dimitrios Mandridis dmandrid@creol.ucf.edu April 29, 2011

2 Objective: Frequency Swept (FM) Mode-locked Laser Develop a frequency swept laser, linear f-sweep, uniform-intensity, low noise, 2. with long-term stability..

3 Outline Applications of frequency swept lasers Our approach Diode based lasers The Theta laser Experimental Results Conclusion 3

4 Outline Applications of frequency swept lasers Our approach Diode based lasers The Theta laser Experimental Results Conclusion 4

5 Introduction Applications of Uniform-Intensity Chirped-Pulse Lasers Time-Stretched Photonic ADC ( Engineering ) [1] Optical Coherence Tomography ( Medical ) [2] Laser Ranging ( Millitary ) [3] [1] Y. Han, and B. Jalali, J. Lightwave Technol., 21(12), 3085 (2003). [2] S. R. Chinn, et al., Opt. Lett. 22(5), (1997). [3] M. U. Piracha, et al., Opt. Expr., 18(7), (2010). 5

6 Outline Applications of frequency swept lasers Our approach Diode based lasers The Theta laser Experimental Results Conclusion 6

7 Approach Semiconductor-Based Frequency Swept MLL Semiconductor gain: Temperature stability Ruggedness Power efficiency Low cost Short carrier lifetime (~ns) [7] GHz repetition rate Low resonator Q (quality) Noisy operation External cavity fiberized (ring): SOA Prolong energy storage Increase oscillator Q Increased laser coherence ISO OC Ultra-low noise lasers 7 P. J. Delfyett, et al., IEEE Journal of Quantum Electronics, 28(10), (1992).

8 Approach Semiconductor-Based Frequency Swept MLL Harmonic mode-locking: Reduced correlation of pulses Increased laser noise Cavity engineering: intra-cavity etalon [8] Correlate intra-cavity pulses Make laser operate as a fundamentally MLL Reduce laser noise 8 S. Gee, et al., IEEE Journal of Photonics Technology Letters, 17(1), (2005).

9 Approach Chirped Pulse Amplification (CPA) CFBG CFBG Amplifier Short Pulse Laser + 9 G. Mourou, Applied Physics B: Lasers and Optics, 65(2), (1997).

10 Theta Laser with Intra-cavity Etalon A Chirped Pulse Oscillator Laser Schematic SOA OC 1 CFBG CIRC OC 2 IM CIRC e-comb Generator SOA: Semiconductor Optical Amplifier ISO: Isolator OC: Output Coupler Circ: Circulator CFBG: Chirped Fiber Bragg Grating : Polarization Controller IM: Intensity Modulator DCF: Dispersion Compensating Fiber FS: Fiber Stretcher Pol: Polarizer BPF: Bandpass filter 10 S. W. Lee, D. Mandridis, and P. J. Delfyett, Optics Express 16, (2008).

11 Theta Laser with Intra-cavity Etalon A Chirped Pulse Oscillator Laser Schematic BPF SOA Generate a uniform-intensity chirped-pulses Low noise? POL Etalon OC 1 CFBG CIRC OC 2 FS DCF IM CIRC e-comb Generator SOA: Semiconductor Optical Amplifier ISO: Isolator OC: Output Coupler Circ: Circulator CFBG: Chirped Fiber Bragg Grating : Polarization Controller IM: Intensity Modulator DCF: Dispersion Compensating Fiber FS: Fiber Stretcher Pol: Polarizer BPF: Bandpass filter 11

12 Theta Laser with Intra-cavity Etalon A Chirped Pulse Oscillator Laser Schematic SOA Hänsch-Couillaud Error Signal PBS BPF CIRC Balanced PD POL Etalon OC 1 CFBG CIRC CIRC OC 2 FS DCF IM e-comb Generator Servo 12 T. W. Hänsch, and B. Couillaud, Optics Communications, 35(3), (1980).

13 13 Theta Laser with Intra-cavity Etalon Laser Photograph

14 Outline Applications of frequency swept lasers Our approach Diode based lasers The Theta laser Experimental Results Conclusion 14

15 Theta Laser with Intra-cavity Etalon Characterization Power (dbm) Power (dbm) High Resolution Optical Spectra db -50 RBW = 1 MHz Frequency (THz) Low Resolution Optical Spectra = 10 nm RBW = 0.05 nm Wavelength (nm) Power (dbm) Intensity (a.u.) Photodetected RF Spectrum Θ-cavity without etalon Θ-cavity with etalon & stabilization scheme RBW = 100 khz SFDR = >100 dbc/hz 80.0M 100.0M 120.0M Frequency (Hz) Sampling Scope Trace Develop a 0.6 T = 10.4 ns uniform-intensity, f = MHz 0.4 F-swept laser, 0.2 Low noise? Time (2.5 ns / div.) 15

16 Theta Laser with Intra-cavity Etalon Amplitude Noise 0-20 AM Noise PSD and Integrated E/E Etalon: OUT IN M( f ) Etalon HWHM M( f ) (dbc/hz) Suppression 30 db k 10k 100k 1M 10M Offset Frequency (Hz) 16

17 Theta Laser with Intra-cavity Etalon Amplitude Noise 0-20 AM Noise PSD and Integrated E/E Etalon: OUT IN M( f ) Etalon HWHM DE/E 1.2 M( f ) (dbc/hz) Low pulse-to-pulse energy noise Suppression 30 db E/E (%) k 10k 100k 1M 10M Offset Frequency (Hz)

18 Outline Applications of frequency swept lasers Our approach Diode based lasers The Theta laser Experimental Results Conclusion 18

19 Theta Laser with Intra-cavity Etalon Conclusion Designed and developed a Theta laser having: uniform-intensity, low noise, f-swept pulses, Advantages of the Theta laser higher and flexible repetition rate, enhanced frequency sweep linearity, period-filling pulses, shown noise characterization. 19 D. Mandridis, et al., "Low noise chirped pulse mode-locked laser using an intra-cavity Fabry-Pérot etalon," Opt. Express 19, (2011).

20 Thank you for your attention! Please join lab tours for more Funding Sources DARPA / PHOBIAC program, NSF / DMR , IEEE Photonics Society Graduate Student Fellowship. 20 D. Mandridis, et al., "Low noise chirped pulse mode-locked laser using an intra-cavity Fabry-Pérot etalon," Opt. Express 19, (2011).

21 Theta Laser with Intra-cavity Etalon Noise Suppression via Intra-cavity Etalon (t-explanation) Fabry Pérot Etalon Harmonic MLL Pulses Pulse Storage / Intermix 21

22 Introduction Applications of Uniform Chirped Pulse Lasers RF-Swept Fixed-Dispersion Laser [1] Filter-swept Laser SOA ISO [2,3] FFP-FC ISO OC FFP-TF Waveform Driver Dispersion-Swept Fixed RF Laser [4] [1] S. Yamashita, and M. Asano, Opt. Express, 14(20), (2006). [2] S. H. Yun, et al., Opt. Lett., 23(11), (1998). [3] R. Huber, M. et al. Opt. Express, 13(9), (2005). [3] M. U. Piracha, et al., Opt. Expr., 18(7), (2010). 22

23 Theta Laser with Intra-cavity Etalon Noise Suppression via Intra-cavity Etalon (f-explanation) A long-term referencing mechanism is needed Free Spectral Range P Etalon Frequency Response f rep. rate N f cavity fcavity f opt. 23

24 Theta Laser with Intra-cavity Etalon Amplitude Modulation Noise - Explanation P t Relative pulse energy variance = Amplitude Modulation (AM) Noise 24