Massively parallel sensing of trace molecules and their isotopologues with broadband subharmonic mid-infrared frequency combs

Multifunctional integrated photonics in the mid-infrared with suspended AlGaAs on silicon

“…The mid-and longwave-infrared (mid-IR and LWIR) spectral regions from λ = 3-8 and 8-15 µm are critical spectral regions for sensitive spectroscopic analysis of a variety of physical compounds such as complex molecular solids, gaseous species and liquid mixtures [1]. Optical frequency combs in particular have been used to achieve broadband spectroscopy with exquisite frequency resolution [2][3][4][5][6][7][8]. However, broadband mid-IR comb technology is still maturing and nearly all systems would greatly benefit from increased spectral coverage, lower power operation and improved robustness.…”

“…arXiv:1905.01380v1 [physics.app-ph] 3 May 2019 have suitable optical transparency [23], and strong optical nonlinearities are also required for the generation or broadening of frequency combs in the mid-IR [15]. While significant Kerr nonlinearity is present in silicon, germanium and chalcogenide materials, they lack intrinsic second-order optical nonlinearities for highly efficient frequency conversion [6,7,24,25] and electro-optic modulation [26].Alternatively, group III-V materials possess many desirable properties for multi-functional integrated photonic systems including a high refractive index, strong second-and third-order optical nonlinearities, and wide optical transparency windows into the LWIR. A practical advantage of these materials is the ability to grow a chemically selective etch stop underneath a high-quality epitaxial device (donor) film, enabling wafer or chip-bonding film transfer techniques for heterogeneous integration [27,28].…”

“…arXiv:1905.01380v1 [physics.app-ph] 3 May 2019 have suitable optical transparency [23], and strong optical nonlinearities are also required for the generation or broadening of frequency combs in the mid-IR [15]. While significant Kerr nonlinearity is present in silicon, germanium and chalcogenide materials, they lack intrinsic second-order optical nonlinearities for highly efficient frequency conversion [6,7,24,25] and electro-optic modulation [26].…”

Directly diode-pumped, Kerr-lens mode-locked, few-cycle Cr:ZnSe oscillator

“…Recently, similar broadband high-brightness mid-infrared radiation have also been generated using high-power femtosecond lasers [9][10][11] at outstanding wavelength and power stability [12]. More intriguingly, the femtosecond nature of such output, especially when in the form of a stabilized frequency comb, opens the way to a multitude of time-and frequency-domain techniques [13][14][15] that can reveal ultrafast dynamics and drastically improve the speed, dynamic range, and many other aspects of spectroscopic measurements [16][17][18][19][20]. Solid-state lasers based on Cr 2+ -doped II-VI material, often called the Ti:Sapphire of the mid-infrared, are reliable sources for directly generating ultrashort femtosecond pulses in the 2-3 μm spectral range [21][22][23][24][25].…”

Multi-octave spanning, Watt-level ultrafast mid-infrared source

“…Broadband light sources are an important enabling technology for the spectroscopic study of molecular vibrations, helping to classify the chemical composition and conformation of a wide range of materials [1]. By illuminating a sample with broadband radiation, it becomes possible to study large ensembles of molecules in a widely parallel manner [2]. In particular, the infrared molecular fingerprint region, spanning from the nearinfrared to the long-wavelength mid-infrared (MIR) (∼2-20 μm), can be used to probe a huge variety of vibrational molecular modes and overtones [3].…”