Mid-Infrared Time-Resolved Frequency Comb Spectroscopy of Transient Free Radicals

Fleisher, Adam J.; Bjork, Bryce J.; Bui, Thinh Q.; Cossel, Kevin C.; Okumura, Mitchio; Ye, Jun

doi:10.1021/jz5008559

Cited by 137 publications

(106 citation statements)

References 37 publications

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“…VIPA-based systems allow fast measurements (on the order of ms), but the simultaneous spectral coverage is limited by the detector size, so recording of the entire comb bandwidth requires sequential measurement and changing the positions of the grating [5]. Moreover, retrieving absorption spectra from the camera images requires rather complex signal analysis [5,15,23] and MIR VIPAs and cameras are quite expensive. However, VIPA-based systems can rather easily be combined with enhancement cavities using a low-bandwidth dither lock, and the high sensitivity and short acquisition time have made possible, e.g., time-resolved measurements of transient radicals [23] and reaction kinetics [24].…”

mentioning

confidence: 99%

“…Moreover, retrieving absorption spectra from the camera images requires rather complex signal analysis [5,15,23] and MIR VIPAs and cameras are quite expensive. However, VIPA-based systems can rather easily be combined with enhancement cavities using a low-bandwidth dither lock, and the high sensitivity and short acquisition time have made possible, e.g., time-resolved measurements of transient radicals [23] and reaction kinetics [24]. Open-air broadband trace gas sensing using a VIPA-based spectrometer has also been demonstrated [5].…”

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confidence: 99%

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Mid-infrared continuous-filtering Vernier spectroscopy using a doubly resonant optical parametric oscillator

et al. 2017

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We present a continuous-filtering Vernier spectrometer operating in the 3.15-3.4 µm range, based on a femtosecond doubly resonant optical parametric oscillator, a cavity with a finesse of 340, a grating mounted on a galvo scanner and two photodiodes. The spectrometer allows acquisition of one spectrum spanning 250 nm of bandwidth in 25 ms with 8 GHz resolution, sufficient for resolving molecular lines at atmospheric pressure. An active lock ensures good frequency and intensity stability of the consecutive spectra and enables continuous signal acquisition and efficient averaging. The relative frequency scale is calibrated using a Fabry-Perot etalon or, alternatively, the galvo scanner position signal. We measure spectra of pure CH 4 as well as dry and laboratory air and extract CH 4 and H 2 O concentrations by multiline fitting of model spectra. The figure of merit of the spectrometer is 1.7×10 −9 cm −1 Hz −1/2 per spectral element and the minimum detectable concentration of CH 4 is 360 ppt Hz -1/2 , averaging down to 90 ppt after 16 s.

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confidence: 99%

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confidence: 99%

Mid-infrared continuous-filtering Vernier spectroscopy using a doubly resonant optical parametric oscillator

et al. 2017

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“…For example, Fleisher et al studied the microsecond dynamic chemical reaction using comb spectroscopy with a virtually imaged phased array. 14 As with other examples, such as observing picosecond phenomena with DCS, a short-time Fourier transform (STFT) was applied to the free induction decay signal from a molecular sample. 4 However, in the STFT scheme, the temporal resolution is restricted due to the Fourier limit.…”

confidence: 99%

Development of ultrafast time-resolved dual-comb spectroscopy

Asahara

Minoshima

2017

APL Photonics

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Ultrafast time-resolved dual-comb spectroscopy (TR-DCS) has been demonstrated, which enables direct observations of transient responses of complex optical spectra by combining dual-comb spectroscopy with the pump–probe method. TR-DCS achieves two-dimensional spectroscopy with a wide dynamic range for both the temporal and frequency axes. As a demonstration, we investigated the femtosecond relaxation dynamics of a photo-excited InGaAs saturable absorber in the near-infrared frequency region. The transient response of the interferogram was successfully obtained, and both the amplitude and phase spectra of the dynamic complex transmittance were independently deduced without using the Kramers-Kronig relations. A high phase resolution in the order of milliradian was achieved by suppressing the effect from the slow phase drift caused in the experimental system. Our proof-of-principle experiment promotes a pathway to coherent, highly accurate, and multi-dimensional pump–probe spectroscopy using the optical frequency comb technology.

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“…For example, individual comb components can be tuned to scan over the frequency gap. [16][17][18][19][20][21] Other methods include spatially separating the comb lines using gratings, 21 Fourier transform spectroscopy of a single OFC 22 and dual-mode spectroscopy using two OFCs. 23,24 Nevertheless, few efforts have been made to decrease the comb spacing to improve the spectral resolution.…”

Section: Introductionmentioning

confidence: 99%

A digitally generated ultrafine optical frequency comb for spectral measurements with 0.01-pm resolution and 0.7-µs response time

Bao

et al. 2015

Light Sci Appl

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Optical spectral measurements are crucial for optical sensors and many other applications, but the prevailing methods, such as optical spectrum analysis and tunable laser spectroscopy, often have to make compromises among resolution, speed, and accuracy. Optical frequency combs are widely used for metrology of discrete atomic and molecular spectral lines. However, they are usually generated by optical methods and have large comb spacing, which limits the resolution for direct sampling of continuous spectra. To overcome these problems, this paper presents an original method to digitally generate an ultrafine optical frequency comb (UFOFC) as the frequency ruler for spectral measurements. Each comb line provides one sampling point, and the full spectrum can be captured at the same time using coherent detection. For an experimental demonstration, we adopted the inverse fast Fourier transform to generate a UFOFC with a comb spacing of 1.46 MHz over a 10-GHz range and demonstrated its functions using a Mach-Zehnder refractive index sensor. The UFOFC obtains a spectral resolution of 0.01 pm and response time of 0.7 ms; both represent 100-fold improvements over the state of the art and could be further enhanced by several orders of magnitude. The UFOFC presented here could facilitate new label-free sensor applications that require both high resolution and fast speed, such as measuring binding kinetics and single-molecule dynamics.

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Mid-Infrared Time-Resolved Frequency Comb Spectroscopy of Transient Free Radicals

Cited by 137 publications

References 37 publications

Mid-infrared continuous-filtering Vernier spectroscopy using a doubly resonant optical parametric oscillator

Mid-infrared continuous-filtering Vernier spectroscopy using a doubly resonant optical parametric oscillator

Development of ultrafast time-resolved dual-comb spectroscopy

A digitally generated ultrafine optical frequency comb for spectral measurements with 0.01-pm resolution and 0.7-µs response time

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