Frequency combs for ultrasensitive molecular detection

Transcription

1 Frequency combs for ultrasensitive molecular detection Konstantin Vodopyanov CREOL Ind. Affil Symp., CREOL, March 13, 2015 Konstantin Vodopyanov p. 1

2 What are frequency combs? Theodor W. Hänsch and John L. Hall 2005 Nobel Prize in Physics Regularly spaced train of short (fs) pulses corresponds to a spectrum consisting of discrete, evenly spaced narrow lines, each having an absolute frequency measurable within the accuracy of an atomic clock. Spectra of the solar photosphere near 1.5 μm overlaid by a Laser Frequency Comb with 15-GHz mode spacing Steinmetz et al. Science 321, 1335 (2008) Konstantin Vodopyanov p. 2

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5 Molecular fundamental resonances wavelength, µm absorption line strength (10-19 cm -1 cm 2 /mol) NH 3 C 2 H 2 CH 4 H 2 O COS H 2 CO CO N 2 O CO 2 N 2 O H 2 CO CH 4 C 2 H 2 HCN N 2 O HCN NH 3 wavenumber, cm -1 Konstantin Vodopyanov p. 5

6 Michelson Interferometer Spectroscopy (Fourier-transform spectroscopy) Michelson, 1907 Source Fourier transform of the autocorrelation is the power spectrum FTIR Detector Wavelength Path difference FFT Sample s transmission spectrum is encoded via the dependence of detector signal vs. beam path difference. Use Fast Fourier Transform! Konstantin Vodopyanov p. 6

7 Comb-based Fourier Transform Spectroscopy Δt Mid-IR Frequency Comb Source time Detector interferogram Mechanically or electronically controlled Fourier Transform Spectrum Adler, F. et al. Mid-infrared Fourier transform spectroscopy with a broadband frequency comb. Opt. Express 18, (2010). Konstantin Vodopyanov p. 7

8 Dual-Comb Fourier Transform Spectroscopy our system based on two phase locked Tm fiber combs Δt Mid-IR Frequency Comb Source 1 Mid-IR Frequency Comb Source 2 time two lasers need to be mutually coherent Detector Fourier Transform Repetition rates of Laser 1 and Laser 2 have small offset of Hz Spectrum Up to 1000 spectra/sec Resolution ~ 100 MHz (0.003 cm -1 ) Schliesser, Brehm, Keilmann, Opt. Express 13, 9029 (2005) Konstantin Vodopyanov p. 8

9 Frequency divide-and-conquer approach to producing mid-ir combs ω 1 ω 2 ω 3 nondegenerate OPO idler f rep signal f rep pump f rep FREQUENCY p s i p s i /2 partly degenerate OPO idler signal pump FREQUENCY degenerate OPO signal & idler pump p 2 s,i /2 FREQUENCY Wong, Vodopyanov, Byer, JOSA B 27, 876 (2010) Konstantin Vodopyanov p. 9

10 Comb lines of the sync-pumped degenerate OPO OPO pump FREQUENCY 0 / 2 f rep f rep A n-1 n n+1 m-1 m m+1 0 B m-1 m m+1 Wong, Vodopyanov, Byer, JOSA B 27, 876 (2010) Marandi, Leindecker, Pervak, Byer, Vodopyanov, Opt. Express 20, 7255 (2012) Konstantin Vodopyanov p. 10

11 = 3 10 µm Tm: fiber =2 µm 90 fs OP-GaAs Konstantin Vodopyanov p. 11

12 Mirror Mirror OP-GaAs Orientation-patterned GaAs (OP-GaAs): reversal period 51.5 µm infrared cutoff of GaAs: 17 µm Konstantin Vodopyanov p. 12

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14 Molecular fundamental resonances wavelength, µm absorption line strength (10-19 cm -1 cm 2 /mol) NH 3 C 2 H 2 CH 4 H 2 O COS H 2 CO CO N 2 O CO 2 N 2 O H 2 CO CH 4 C 2 H 2 HCN N 2 O HCN NH 3 wavenumber, cm -1 Konstantin Vodopyanov p. 14

15 Spectral resolution of comb method = mode spacing ~ 100 MHz cm x 20 x comb teeth Konstantin Vodopyanov p. 15

16 Intracavity optical sensing: methane FTIR resolution cm -1 Magnus Haakestad experiment simulation Modulation of the OPO spectrum near λ = 3.3 μm associated with intracavity methane absorption. Konstantin Vodopyanov p. 16

17 Detection of trace molecules Formaldehyde (CH 2 O) Ethylene (C 2 H 4 ) experiment experiment simulation Carbon monoxide (CO) Isotopic 13 CO 2 in air (4 ppm) experiment experiment simulation simulation Konstantin Vodopyanov p. 17

18 Dual-comb spectroscopic results: the spectrum (400k points) is taken in ~ 1ms, 5 sec with averaging Oscilloscope traces, max 400k points, 8 bit 100µs/div CO2 optical spectrum 10µs/div 1µs/div HITRAN database RF spectrum, after FFT wavenumber, cm -1 frequency / MHz Konstantin Vodopyanov p. 18

19 NH3 molecule, 0.1 atm Single spectrum 8 ms, with averaging 5 sec experiment HITRAN Optical spectra were obtained by referencing to RF frequencies f rep &Δf rep. Absolute optical frequency referencing better than 0.1 cm -1 Konstantin Vodopyanov p. 19

20 NASA astrobiology project NASA grant: NNX09AW13G, " Laser Sensor for In-Situ Detection of Chemical and Organic Biomarkers and Isotopes " Detector receives the signal back because of the diffuse reflection Konstantin Vodopyanov p. 20

21 (a) Standoff and remote molecular sensing Sensing comb Multipass cell IR detector Lock LO comb IR spectrum ADC FFT (b) Sensing comb Lock Backscattered light LO comb IR detector ADC FFT IR spectrum Konstantin Vodopyanov p. 21

22 Biomarkers in human breath... concept that breath contains molecules that originated from normal or abnormal physiology... Animals can be used for sensitive diagnostics Hippocrates of Kos Antoine Lavoisier Linus Pauling carbonyl sulfide - liver disease, transplant rejection nitric oxide - asthma methane - gut bacteria carbon dioxide stomach ulcer H2O CH4 COS NO H2O CH4 NH3 NH3 ammonia liver disease, renal failure C2H6 CO2 C2H6 ethane, pentane lipid peroxidation HCN C5H12 CH2O CO C5H12 CH2O HCN ethane, pentane lipid peroxidation acetone acetone formaldehyde - breast cancer carbon monoxide - asthma, hyperbilirubinemia hydrogen cyanide - cystic fibrosis acetone - diabetes Konstantin Vodopyanov p. 22

23 Biomedical research with laser combs Dr. Steven R. Smith Translational Research Institute for Metabolism and Diabetes at Florida Hospital (Orlando). Exhaled methane, carbon dioxide Prof. Lauri Halonen, Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, Finland.. energy derived from fat, protein, and carbohydrates Exhaled hydrogen cyanide (HCN), ammonia (NH3) and acetylene (C2H2) Konstantin Vodopyanov p. 23

24 New pump source: Kerr-lens mode-locked Cr:ZnS laser. Extending mid-ir comb to 2 octaves. Fiber laser pump, 1567 nm = 2.35 µm Cr 2+ :ZnS Konstantin Vodopyanov p. 24

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26 Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, Finland Konstantin Vodopyanov p. 26

27 Dual-comb 2-µm Tm fiber laser system at CREOL Konstantin Vodopyanov p. 27

28 Dual-comb Tm-laser system at 2 µm N x f rep for Laser 1 (N+1) x f rep for Laser 2 N 1.7 MILLION Laser 1 OPTICAL FREQUENCY Laser 2 = nm lasers 1554-nm laser f rep is stable to < 1Hz Δf rep is stable to < 1mHz f rep is quantized in steps of approx. 70 Hz But it is not necessary that Δf rep is quantized, because f beat1 or f beat2 offsets can be set to different values for two lasers (Δf rep =20 Hz in some experiments) Konstantin Vodopyanov p. 28

29 Dual-comb experiments with two phase-locked ultrafast 2-µm Tm lasers. Repetition rate offset: 20 Hz locked Laser 1 Laser 2 1 µs/div gas cell detector beam combiner to oscilloscope Konstantin Vodopyanov p. 29

30 AFM spectroscopy with nanometer resolution (Laurene Tetard) Sensing comb Lock Backscattered light Local Oscillator comb IR detector Analogue-to-digital conversion & FFT IR spectrum Konstantin Vodopyanov p. 30

31 New pump source: Kerr-lens mode-locked Cr:ZnS laser Fiber laser pump, 1567 nm = 2.35 µm Cr 2+ :ZnS Konstantin Vodopyanov p. 31

32 Different animals are used for sensing molecules Konstantin Vodopyanov p. 32

33 Parametric gain curves: pump at 2.35 µm OP-GaAs (0.5mm, QPM 88µm) vs OP-GaP (0.5mm, QPM 110µm) vs OP-ZnSe (0.5mm, QPM 205µm) ZnSe degeneracy 4.7 µm Wavelength (µm) Konstantin Vodopyanov p. 33

34 Biomarkers in human breath... concept that breath contains molecules that originated from normal or abnormal physiology... nitric oxide -Asthma methane -Gut bacteria carbonyl sulfide -Liver disease, transplant rejection carbon dioxide -Stomach ulcer H2O CH4 COS NO H2O CH4 NH3 NH3 ammonia -Liver disease, renal failure C2H6 CO2 C2H6 ethane, pentane - Lipid peroxidation HCN C5H12 CH2O CO C5H12 CH2O HCN ethane, pentane - Lipid peroxidation acetone acetone formaldehyde -Breast cancer carbon monoxide -Asthma, hyperbilirubinemia hydrogen cyanide -Cystic fibrosis acetone -Diabetes Konstantin Vodopyanov p. 34

35 Biomarkers in human breath... concept that breath contains molecules that originated from normal or abnormal physiology... Hippocrates of Kos Antoine Lavoisier Linus Pauling nitric oxide - Asthma methane - Gut bacteria carbonyl sulfide - Liver disease, transplant rejection carbon dioxide - Stomach ulcer H2O CH4 COS NO H2O CH4 NH3 NH3 ammonia - Liver disease, renal failure C2H6 CO2 C2H6 ethane, pentane - Lipid peroxidation HCN C5H12 CH2O CO C5H12 CH2O HCN ethane, pentane - Lipid peroxidation acetone acetone formaldehyde - Breast cancer carbon monoxide - Asthma, hyperbilirubinemia hydrogen cyanide - Cystic fibrosis acetone - Diabetes Konstantin Vodopyanov p. 35