1,720,980 research outputs found
Compact Cr:ZnS channel waveguide laser operating at 2333 nm
Get PDFA compact mid-infrared channel waveguide laser is demonstrated in Cr:ZnS with a view to power scaling chromium laser technology utilizing the thermo-mechanical advantages of Cr:ZnS over alternative transition metal doped II-VI semiconductor laser materials. The laser provided a maximum power of 101 mW of CW output at 2333 nm limited only by the available pump power. A maximum slope efficiency of 20% was demonstrated
Silicon nitride based light sources tailored for coherent Raman scattering
No full textSilicon nitride waveguides offer a high nonlinear refractive index and tight mode confinement, ideal for efficient four-wave mixing (FWM) processes. We present a light source for broadband as well as narrowband coherent anti-Stokes Raman scattering (CARS), with the potential to be set up as an all-integrated device, based on FWM in silicon nitride waveguides. Signal and idler pulses are generated via FWM with only 4 nJ input pulse energy and stimulated using a tunable continuous-wave seed source, such that the idler and residual pump pulses can be used for CARS measurements, enabling chemically-selective label-free imaging across the entire fingerprint region
Supercontinuum generation in orientation-patterned gallium phosphide
No full textSupercontinuum generation in bulk media is not normally observed at the nJ-level pulse energies available from high-repetition-rate femtosecond oscillators. Here, we present results demonstrating how a visible supercontinuum can be produced in bulk orientation-patterned gallium phosphide from 100-MHz 1040-nm femtosecond pulses with energies of up to 32 nJ. High-order parametric gain near 550 nm, seeded by self-phase-modulated spectral sidebands, underpins this new and simple supercontinuum process which yields an output spectrum spanning from the blue/green to the red.</p
Molecular spectroscopy from 5-12 μm using an OP-GaP OPO
Get PDFWe report a femtosecond optical parametric oscillator (OPO) based on the new semiconductor gain material orientation patterned gallium phosphide (OP-GaP) and being the first example of a broadband OPO operating across the molecular fingerprint region. OP-GaP crystals with lengths of 1 mm and several patterning periods were diced, polished, and anti- reflection (AR) coated for near- to mid-infrared wavelengths. We configured a synchronously pumped OP-GaP OPO in a 101.2-MHz resonator with high reflectivity from 1.15–1.35 μm, pumped with 150-fs pulses from a 1040-nm femtosecond laser (Chromacity Spark). The coating of one spherical mirror was optimized for transmission at the pump wavelength of 1040 nm and for high reflectivity at the resonant signal wavelength in a range from 1.15–1.35 μm, while the other spherical mirror collimated the idler beam emerging from the OP-GaP crystal and was silver coated to provide high reflectivity for all idler wavelengths. This collimated idler beam was output-coupled from the cavity by transmission through a plane mirror coated with high transmission for the idler wavelengths (5–12 μm) and high reflectivity for the signal wavelengths (1.15–1.35 μm) on an infrared-transparent ZnSe substrate. Idler spectra centered from 5.4–11.8 μm and extending to 12.5 μm were collected. The maximum average power was 55 mW at 5.4 μm with 7.5 mW being recorded at 11.8 μm. Details of Fourier transform spectroscopy using water vapor and a polystyrene reference standard are presented
Mixed type I and II BBO OPO pumped at 355 nm provides good beam quality, bandwidth, and efficiency
Get PDFFor ns 355nm pumped simple type II BBO OPOs, two problems still remain even after rotated cavity design 1,2. The first problem is that the efficiency is still low. The other problem is the requirement of adjusting the waveplate inserted in the rotated cavity during the wide tuning range. Here, we propose and demonstrate a simple prism rotated cavity1, which uses both a type I and a type II BBO crystals pumped at 355nm
Robust optimization of single-cycle THz setups based on phase-matching via tilted pulse fronts using an incident-fluence metric
No full textDespite the popularity and ubiquitousness of the tilted-pulse-front technique for single-cycle terahertz (THz) generation, optimization of the experimental setup remains complex and difficult due to the sensitive dependence on and coupling between the optical pulse parameters, including fluence, beam size, angular dispersion and temporal compression. Here we present a systematic and robust method to tune the tilted pulse-front setup, based on use of selected multi-dimensional scans, which enables a straight-forward and accurate determination of optimum parameter values. Our methodology not only allows us to determine parameter sensitivities and achieve a robust optimum in the performance, but also enables a verification of certain physical properties of the lithium niobate prism, including the THz refractive index. The detailed step-by-step procedure is discussed and applied to a tilted-pulse-front THz setup at both room temperature and cryogenic temperatures. The procedure can be applied to any setup based on the tilted-pulse-front geometry and is important for the construction of high energy THz sources required for strong field terahertz applications such as novel particle acceleration schemes or beam manipulators
High-average-power, mid-infrared, widely tunable, picosecond optical parametric oscillator based on OP-GaAs
No full textThis paper reports a high-average-power mid-infrared source based on an orientation-patterned gallium arsenide (OP-GaAs) optical parametric oscillator (OPO) with wide wavelength tunability. An average power of 4.8 W of signal (3093 nm) and 3.5 W of idler (5598 nm) was achieved at a pump power of 25.5 W. Tuning ranges of 2895 nm-3342 nm (signal) and 4935 nm-6389 nm (idler) were obtained. The idler-resonant OPO offered good beam quality of the mid-infrared idler waves with an M2 of 1.1. High-average-power induced thermal effects for the OP-GaAs OPO were observed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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