Quantum Imaging Technologies: Quantum Laser Radar

Transcription

1 MURI 2005 Quantum Imaging: New Methods and Applications Year 4 Review / 13 November 2009 / Northwestern University, Evanston, IL Quantum Imaging Technologies: Quantum Laser Radar Prem Kumar and Geraldo Barbosa EECS Department, Northwestern University, Evanston, IL s: kumarp@northwestern.edu; g-barbosa@northwestern.edu Jeffrey Shapiro Research Laboratory of Electronics, MIT, Cambridge, MA jhs@mit.edu Support: U. S. Army Research Office Multidisciplinary University Research Initiative Grant No W911NF Quantum Imaging Review, NU, 13 Nov 09 Slide # 1

2 Quantum Laser Radar Classical or Quantum Target Glint / Speckle Transmitter Receiver Optical Pre-processing Optical Post-processing Transmit Optics Receive Optics Atmospheric Turbulence Direct Heterodyne Homodyne PIA PSA (2) (3) Quantum return severely degraded by loss keep quantum local PIA = Phase Insensitive Amplifier PSA = Phase Sensitive Amplifier Quantum Imaging Review, NU, 13 Nov 09 Slide # 2

3 Pictorial View of Amplification of Coherent Input Light E = X + i Y Y Phasesensitive Phaseinsensitive Y out2 = (2G -1) in 2 X X Y X2 = g in 2 Y2 = g -1 in 2 t E = X cos t -Ysin t X Quantum Imaging Review, NU, 13 Nov 09 Slide # 3

4 Simulation of Preamplified Photodetection of Shot-Noise Limited Signals Simulation of the amplification of a gray-scale image in the shot-noise limited regime Random zero-mean Gaussian noise is added to represent detector noise A valid model when the received signal photon number per pulse or per inverse bandwidth is not too small Photocurrents in the unamplified and amplified cases are scaled appropriately for fair comparison. Quantum Imaging Review, NU, 13 Nov 09 Slide # 4

5 Simulation of Preamplified Photodetection of Shot-Noise Limited Signals For G = 1 (no preamplification) SNR IN = N s (shot-noise limited signal) N s Efficiency 0 1 Ideal Detector ( N s ) 2 = N s, SNR OUT = N s NF = SNR IN / SNR OUT = 1/ For G > 1 SNR IN = N s and ( N s ) 2 = N s N s G Output = GN s. Find ( N s ) 2 G from: NF = SNR IN / SNR OUT = N s / [( GN s ) 2 / ( N s ) 2 G ] or ( N s ) 2 G = NF ( GN s ) 2 / N s = ( N s ) 2 G 2 NF Quantum Imaging Review, NU, 13 Nov 09 Slide # 5

6 Simulation of Preamplified Photodetection of Shot-Noise Limited Signals Noise Figure (NF): [PRL 83 (10), pp , Choi, Vasilyev & Kumar] NF tot = NF amp + (1 - ) / ( G) NF PSA = 1 (NF PSA ) tot = 1 + (1 - ) / ( G) NF PIA = 2 1/G (NF PIA ) tot = 2 (1 1/G) + 1 / ( G) Also, the detected signal in each case is different. So, we scale PSA & PIA noise by G 2 in order to fairly compare the photo-current between the three cases. Therefore, added noise: No gain ( N s ) 2 PSA [1 + (1 - ) / ( G)] ( N s ) 2 PIA [2(1 1/G) + 1/( G)] ( N s ) 2 Quantum Imaging Review, NU, 13 Nov 09 Slide # 6

7 Simulation of Potential Advantage Although shown here for a spatially broadband case, our goal in the MURI is to do proof-of-principle experiments with raster scanning of the image with use of a fiber-based PSA. Soft Gaussian Frequency Filter FFT Start w/ image Add noise per spatial frequency: ( N s ) 2 When G = 1 IFFT [1 + (1 )/( G)] ( N s ) 2 For PSA [ 2(1 1/G) + 1/( G)] ( N s ) 2 For PIA Result Quantum Imaging Review, NU, 13 Nov 09 Slide # 7

8 Results: Averaged over 100 Frames = 0.8, G = 10 db Target (no average) No gain PSA gain PIA gain One frame after IFFT (no average) Quantum Imaging Review, NU, 13 Nov 09 Slide # 8

9 Results: Averaged over 100 Frames = 0.3, G = 10 db Target (no average) No gain PSA gain PIA gain One frame after IFFT (no average) Quantum Imaging Review, NU, 13 Nov 09 Slide # 9

10 Noise Figure Measurement of the Fiber PSA Lim, Grigoryan, Shin, & Kumar, OFC 2008 NF ave (Anti-Stokes) = (0.42 ± 0.53) db NF ave (Stokes) = (0.68 ± 0.59) db Quantum Imaging Review, NU, 13 Nov 09 Slide # 10

11 Proposed Proof-of-Principle Experiment Quantum Imaging Review, NU, 13 Nov 09 Slide # 11

12 Experiment in Progress Source laser (CW nm) modulated signal EDFA Pre- Amplifier Transmitter Signal Generation 30GHz Double sideband modulation Phase modulation SBS suppression Phase-lock loop Phase-delay generator PSA Based Receiver Feed back HNLF with Faraday mirror terminal Optical signal Electrical signal Three-stage FBG sideband separator Circulator Test pattern Free space testbed EDFA PSA Output Quantum Imaging Review, NU, 13 Nov 09 Slide # 12

13 PSA Schematic Quantum Imaging Review, NU, 13 Nov 09 Slide # 13

14 PSA Laboratory Quantum Imaging Review, NU, 13 Nov 09 Slide # 14

15 PSA Attenuation Schematic Quantum Imaging Review, NU, 13 Nov 09 Slide # 15

16 PSA Attenuation Results Half-wave plate rotated to achieve 15 db of attenuation in the signal and idler. Pump stays at constant level due to variable optical attenuator. Quantum Imaging Review, NU, 13 Nov 09 Slide # 16

17 PSA Attenuation Results Gain stays relatively constant over the range of attenuation. SNR ratio decreases with increased attenuation. Quantum Imaging Review, NU, 13 Nov 09 Slide # 17

18 PSA Imaging Schematic Quantum Imaging Review, NU, 13 Nov 09 Slide # 18

19 PSA Imaging Signal 10 db Signal Gain 20 db SNR Quantum Imaging Review, NU, 13 Nov 09 Slide # 19

20 One Dimensional Scan 1 cm 6 mm Three gray bars printed on transparency at 1200 dpi. 60%, 70%, 80% gray bars with transparent background. Transparency taped and sandwiched between two glass slides. Quantum Imaging Review, NU, 13 Nov 09 Slide # 20

21 One Dimensional Scan Results PSA Output Input Quantum Imaging Review, NU, 13 Nov 09 Slide # 21

22 PSA Imaging Decreased Signal Signal Output Signal Input Low light imaging of target. 6 db Signal Gain 1 db SNR Quantum Imaging Review, NU, 13 Nov 09 Slide # 22

23 Northwestern N Raster Scan 3.5 mm Northwestern N printed on transparency at 1200 dpi. 70% gray scale background with 60% gray scale letter. Transparency taped and sandwiched between two glass slides mm Quantum Imaging Review, NU, 13 Nov 09 Slide # 23

24 Northwestern N Imaging Results 3.5 mm mm Input PSA Output Quantum Imaging Review, NU, 13 Nov 09 Slide # 24

25 Future Applications Near-Field Scanning Optical Microscopy (NSOM) Betzig & Trautman, Science 257 pp Dunn, Chem. Rev. 99 pp Genet & Ebbesen, Nature 445 pp Quantum Imaging Review, NU, 13 Nov 09 Slide # 25

26 Typical NSOM Setup Transmission Reflection Collection Illumination/Collection van Hulst, et al. J. Stuct. Biol. 119 pp Quantum Imaging Review, NU, 13 Nov 09 Slide # 26

27 PSA Assisted NSOM Quantum Imaging Review, NU, 13 Nov 09 Slide # 27

28 NSOM Examples Fluorescence imaging of DNA van Hulst, et al. J. Stuct. Biol. 119 pp Quantum Imaging Review, NU, 13 Nov 09 Slide # 28

29 NSOM Examples Photonic crystal nanocavities Okamoto, et al. Appl. Phys. Lett. 82 pp Quantum Imaging Review, NU, 13 Nov 09 Slide # 29