Terahertz generation by optical rectification in chalcopyrite crystals ZnGeP, CdGeP and CdSiP.

Optical rectification of near-infrared laser pulses generates broadband terahertz radiation in chalcopyrite crystals CdGeP, ZnGeP and CdSiP. The emission is characterized using linear-polarized excitation from 0.8 eV to 1.

Multi-watt, multi-octave, mid-infrared femtosecond source.

Spectroscopy in the wavelength range from 2 to 11 μm (900 to 5000 cm) implies a multitude of applications in fundamental physics, chemistry, as well as environmental and life sciences. The related vibrational transitions, which all infrared-active small molecules, the most common functional groups, as well as biomolecules like proteins, lipids, nucleic acids, and carbohydrates exhibit, reveal information about molecular structure and composition. However, light sources and detectors in the mid-infrared have been inferior to those in the visible or near-infrared, in terms of power, bandwidth, and sensitivity, severely limiting the performance of infrared experimental techniques.

Compact and efficient mid-IR OPO source pumped by a passively Q-switched Tm:YAP laser.

We describe a compact and efficient mid-infrared (mid-IR) source based on zinc germanium phosphide (ZGP) and cadmium silicon phosphide (CSP) optical parametric oscillators (OPOs), operating in near degenerate condition, directly pumped by a 1.94 μm thulium (Tm)-doped yttrium-aluminum-perovskite (YAP) laser. The Tm:YAP laser is passively Q-switched by a chromium-doped zinc sulfide saturable absorber, and is operated to 4 W average power with a peak power of 29 kW.

Femtosecond-laser pumped CdSiP₂ optical parametric oscillator producing 100 MHz pulses centered at 6.2 μm.

We report the first, to the best of our knowledge, femtosecond-laser-pumped optical parametric oscillator (OPO) based on the newly developed nonlinear crystal, CdSiP₂. The OPO was synchronously pumped by a mode-locked Yb:KYW/Yb:fiber master-oscillator power amplifier, providing 1.053 μm pump pulses with durations of 130 fs at a repetition rate of 100 MHz.

Narrow-bandwidth, ~100 ps seeded optical parametric generation in CdSiP2 pumped by Raman-shifted pulses at 1198 nm.

Low-threshold, efficient optical parametric generation at ~4.64 μm is demonstrated using CdSiP2 nonlinear crystal pumped by 150 ps Raman shifted pump pulses at 1198 nm in noncritical configuration at 1 kHz repetition rate. Maximum single pulse idler energy of 6 μJ and total conversion efficiency of 30% are achieved.

Narrow-bandwidth, mid-infrared, seeded optical parametric generation in 90° phase-matched CdSiP2 crystal pumped by diffraction limited 500 ps pulses at 1064 nm.

Low-threshold, efficient optical parametric generation at ~6100 nm is demonstrated using CdSiP2 nonlinear crystal at 1 to 10 kHz repetition rates with relatively long 500 ps pump pulses at 1064 nm. Maximum single pulse energy of 8.7 μJ and average power of 79 mW are achieved for the idler.

Optical parametric generation in CdSiP2 at 6.125 μm pumped by 8 ns long pulses at 1064 nm.

A 21.4 mm long noncritically cut CdSiP2 crystal, pumped by 8 ns pulses at 1064 nm in a double-pass configuration for pump, signal, and idler, generated 523 μJ, 5.8 ns idler pulses at 6.

Phase-matching properties and refined Sellmeier equations of the new nonlinear infrared crystal CdSiP2.

We directly measured the second harmonic generation and difference frequency generation phase-matching directions of the nonlinear crystal CdSiP(2) until 9.5 μm using the sphere method. The simultaneous fit of the experimental angular data allowed the Sellmeier equations of the ordinary and extraordinary principal refractive indices to be refined over the entire transparency range of the crystal.

Subnanosecond, 1 kHz, temperature-tuned, noncritical mid-infrared optical parametric oscillator based on CdSiP(2) crystal pumped at 1064 nm.

Operation of an optical parametric oscillator based on CdSiP(2) and pumped at 1064 nm is demonstrated at a repetition rate of 1 kHz. The maximum output idler energy of 24 microJ at 6.125 microm corresponds to an average power of 24 mW.

Noncritical singly resonant synchronously pumped OPO for generation of picosecond pulses in the mid-infrared near 6.4 microm.

The recently developed chalcopyrite CdSiP(2) is employed in a picosecond, 90 degrees -phase-matched, synchronously pumped, optical parametric oscillator pumped at 1064 nm to produce steady-state idler pulses near 6.4 microm with an energy as high as 2.8 microJ at 100 MHz, in a train of 2-micros-long macropulses following at a repetition rate of 25 Hz.

Noncritical singly resonant optical parametric oscillator operation near 6.2 microm based on a CdSiP(2) crystal pumped at 1064 nm.

CdSiP(2) is employed in a nanosecond, 90 degrees -phase-matched, singly resonant optical parametric oscillator pumped at 1064 nm to produce idler pulses near 6.2 microm with an energy as high as 470 microJ at 10 Hz.

Infrared reflectance and photoemission spectroscopy studies across the phase transition boundary in thin film vanadium dioxide.

Optical properties and valence band density of states near the Fermi level of high-quality VO(2) thin films have been investigated by mid-infrared reflectometry and hard-UV (hν = 150 eV) photoemission spectroscopy. An exceptionally large change in reflectance from 2 to 94% is found upon the thermally driven metal-insulator transition (MIT). The infrared dispersion spectra of the reflectance across the MIT are presented and evidence for the percolative nature of the MIT is pointed out.