We present a narrowband, non-resonant optical parametric oscillator based on 5-mm thick Rb-doped periodically-poled KTiOPO4 (PPKTP) operating in the high-energy/low repetition-rate regime. An uncoated volume Bragg grating (VBG) is employed as one of the cavity mirrors reflecting only the signal whereas the other cavity mirror is reflecting only the idler. Pumping by a Nd:YAG laser at 1.0642 μm in a double-pass, the signal plus idler output energy reached almost 5 mJ at a repetition rate of 100 Hz corresponding to a conversion efficiency of ⁓26%. Both signal and idler are narrowband with full width at half maximum (FWHM) of 0.5 nm at 1942 nm and 0.76 nm at 2355 nm, respectively.
We report on efficient mid-IR difference-frequency generation (DFG) at ~8 μm in orientation-patterned GaAs (OPGaAs), by mixing the signal and idler fields inside a nanosecond, singly-resonant, periodically-poled MgO-doped LiNbO3 optical parametric oscillator (OPO). The temperature and spectral acceptance bandwidths as well as the DFG output performance are compared for two OP-GaAs samples with different lengths. Temperature tuning of the DFG is studied by implementing a transversely chirped Volume Bragg Grating (VBG) as one of the OPO cavity mirrors for the signal wave. The maximum DFG average power amounts to 215 mW at 8.15 μm for a pulse repetition rate of 35 kHz. The corresponding overall optical conversion efficiency from 1 to 8 μm is ~1.1%.
This paper presents the design and radiation characteristics of compact THz molecular laser with optical pumping for photoacoustic spectroscopy are reported. As a pump source, the compact CO2 laser set in a pulse-periodic operation mode with radiation pulse power up of 100W is used. The wavelength tuning range of CO2 laser is from 9.17 to 10.93 μm on the 92 emission line of 12C16O2 molecule. Construction of the THz laser allows for switching between 3 different active mediums. Preliminary experiments showed the laser operating on 10 emission lines of methanol 12CH316OH with a wavelength range of 73-210 μm and a pulse power of up to 100 mW.
The optical parametric oscillator based on the first PPKTP crystal produced in Russia was created. This crystal has dimensions of 8×0.5×10 mm and polling period of Λ1=37.9 μm, Λ2=38.7 μm. The conversion efficiency of pump into idler at repetition rate 1 kHz is 7.5%, quantum efficiency 17.8% and slope efficiency 16.3%. The generation threshold was 110 μJ. The optical parametric oscillator based on the first PPKTA crystal was developed. Threshold for parametric generation was 130 μJ (14.4 MW/cm2), the quantum efficiency was 27% and the differential efficiency was 12%. The signal wavelength was 1.54 μm, and the idler wavelength corresponded to 3.31 μm.
Optical parametric oscillator based on Russian domestic PPKTP structure was created. High quality KTP crystals, of resistivity as high as~1013 Ohm*cm and coercive electric field as low as 2,3 kV/mm weregrownat Crystals of Siberia Ltd.,and 1.8 mm-thick substrates were processed at Labfer Ltd.
A singly-resonant OPO (SRO) based on AgGaSe2 (AGSe) intracavity pumped at ~1.85 μm by the signal pulses of a Rb:PPKTP doubly-resonant OPO (DRO) provided extremely broad tuning (5.8 to ~18 μm) for the non-resonated idler. In a similar set-up with the same nonlinear crystals, we studied intracavity difference-frequency generation (DFG). Both AGSe and the new monoclinic crystal BaGa4Se7 (BGSe) generated single pulse energies of ~0.7 mJ near 7 μm at an overall conversion efficiency from the 1.064 μm pump of 1.2%. The main advantage of BGSe is its damage resistivity up to the maximum pump levels applied at 100 Hz.
The results of measuring of biomarkers in breath air of patients with broncho-pulmonary diseases using wide-band frequency tuning IR laser photo-acoustic spectroscopy and the methods of data mining are presented. We will discuss experimental equipment and various methods of intellectual analysis of the experimental spectra in context of above task. The work was carried out with partial financial support of the FCPIR contract No 14.578.21.0082 (ID RFMEFI57814X0082).
A human exhaled air analysis by means of infrared (IR) laser photoacoustic spectroscopy is presented. Eleven healthy nonsmoking volunteers (control group) and seven patients with chronic obstructive pulmonary disease (COPD, target group) were involved in the study. The principal component analysis method was used to select the most informative ranges of the absorption spectra of patients’ exhaled air in terms of the separation of the studied groups. It is shown that the data of the profiles of exhaled air absorption spectrum in the informative ranges allow identifying COPD patients in comparison to the control group.
We demonstrate an optical parametric oscillator (OPO) based on two HgGa2S4 (HGS) crystals with exceedingly wide tuning range from 4.2 μm to 10.73 μm. The HGS OPO was pumped by Q-switched Nd:YLF laser at 1.053 μm with a 5-7 ns pulse duration. Absorption spectrum of ammonia was presented to demonstrate the feasibility of the OPO system for spectroscopic measurements and gas detection.
A. Boyko, A. Karapuzikov, S. Chernikov, V. Spitcin, Yu. Ponomarev, M. Starikova, M. Yu. Shtyrov, I. Kuznetcova, I. Tikhonyuk, I. Miroshnichenko, M. Miroshnichenko
We report automated waveguide RF excited 13С16О2 - laser based on Z-shaped resonant cavity. The laser possesses possibility of wavelength tuning from 9.5 to 11.5 μm by means of the cavity's diffraction grating position management. The diffraction grating position is driven by precision motorized linear actuator. The lasing lines of P-branch from 11.04 to 11.31 μm were studied in details. Operating mode selection is performed with specially designed PC software "Tunable CO2 – Laser". P-branch 11P(10) – 11P(32) lines' tuning time does not exceed 3 sec.
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