Optical Parametric Converter Research Articles

In situ thermal characterisation and filamentary modification in Polymethylpentene

Polymethylpentene (PMP) polymers can be used to make advanced optics, especially for midinfrared (MIR) ultrafast optics. In this study, an optical parametric converter pumped by a Ti sapphire femtosecond laser was used to investigate the polymer. The thermal effect generated by loosely focused femtosecond near mid-infrared (MIR) pulses in bulky materials is observed in real-time, and the polymer exhibits thermal stability and conformability. To avoid strong linear absorption and to increase the nonlinear damage threshold, the spectral region for ultrafast applications is 1310 nm (0.95 eV)–1350 nm (0.92 eV). For the process in region VI, there is a sign of stronger coupling for short-wavelength photons, and the pulse duration is recommended to be lower than 160 fs. In the ultraviolet (UV) region, filamentary writing using a low-focused beam, the laser peak power was selected in the range of 2.2 MW–9.2 MW. High-density bulky gratings were written. The refractive-index modulation was significant, and the polymer exhibited highly nonlinear features. This study provides insights into the applications and production of PMP polymers in laser optics and laser engineering.

Mid-infrared parametric wavelength conversion seeded with fiber optical parametric sources

A new method of seeding X2 optical parametric converters with X3 fiber optical parametric sources is introduced. We demonstrate a tunable mid-infrared source operating at around 3 µm with the technique and discuss the potential of this architecture.

Efficient low-energy near-infrared KTiOPO_4 optical parametric converter

We report a widely tunable near-infrared holosteric KTiOPO(4) optical parametric converter featuring a low pump energy threshold and high conversion efficiency. The converter uses two 10-mm-long crystals in a simple optical parametric oscillator amplif ier configuration and is tunable from 750 to 1040 nm for the signal. The pump energy threshold at 920 nm is 0.44 mJ for the 532-nm 8-ns 50-Hz input. The system produces as much as 0.45 mJ of energy at 920 nm with an external pump-to-signal energy conversion efficiency of 27% for pump inputs from just two times the threshold value. The internal pump-to-signal and idler energy conversion efficiency is estimated to be 58%. The low pump energy requirement of this system makes it compatible with small laser-diode-pumped solid-state lasers.

Influence of optical parameters of a crystal on the precision of brightness determination by a quantum photometer

An analysis is made of the effects of reflection and absorption of radiation in an optical parametric converter used to measure the absolute spectral density of the energy brightness with a quantum photometer. A universal method is proposed for calculating a correction factor which eliminates systematic errors that can appear when the brightness is measured by parametric conversion in a crystal where the signal, measured, or pump waves experience absorption and reflection. Expressions for the correction factor are obtained for converters of different geometry. These expressions give the factor in terms of the absorption and reflection coefficients of the faces of a crystal for all the waves participating in the parametric interaction process.

Use of an optical parametric converter in determination of the brightness of radiation emitted by a thermal source

A new method was developed for the absolute determination of the brightness of thermal radiation with the aid of a parametric converter (Klyshko method). The brightness of zero fluctuations of electromagnetic vacuum was used as a standard. The brightness of 3900 nm radiation emitted by cw thermal sources, heated to ~1000°K, was determined. An analysis was made of a photon meter prototype system for the determination of the brightness of light fluxes by the Klyshko method.