Frequency down-conversion of solid-state laser sources to the mid-infrared spectral range using non-oxide nonlinear crystals

Since the proof-of-principle demonstration of optical parametric amplifier to efficiently amplify chirped pulses in 1992, optical parametric chirped pulse amplification (OPCPA) became a widely recognized and rapidly developing technique for high-power femtosecond pulse generation. In the meantime, we are witnessing an exciting progress in the development of powerful and ultrashort pulse laser systems that employ chirped pulse parametric amplifiers. These systems cover a broad class of femtosecond lasers, with output power ranging from a few gigawatts to hundreds of terawatts, with a potential of generating few-optical-cycle pulses at the petawatt power level. In this paper, we discuss the main issues of optical parametric chirped pulse amplification and overview recent progress in the field.

Trends in chirped pulse optical parametric amplification

We have generated an ultrabroad mid-infrared continuum by using single-pass optical parametric generation (OPG) in orientation-patterned GaAs (OP-GaAs). The spectrum spans more than an octave, from 4.5 to 10.7 µm, measured 20 dB down from the peak. The 17.5 mm long, 0.5 mm thick, all-epitaxially-grown OP-GaAs sample with a 166.6-µm quasi-phase-matching period was pumped with 3.1-3.3 µm wavelength, 1 ps pulses up to 2 µJ in energy. The OPG threshold was observed at 55 nJ pump energy with the pump polarized along the [111] crystal direction. The slope efficiency near threshold was 51%, and the external conversion efficiency was as high as 15%.

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Optical parametric generation of a mid-infrared continuum in orientation-patterned GaAs.

We review the physical properties, linear and nonlin- ear optical characteristics, and phase-matching configurations of BiB3O6 (BIBO), the first low-symmetry (monoclinic) inor- ganic nonlinear crystal that has found broad applications for frequency conversion of laser sources from the UV, across the visible, to the near-IR based on three-wave interactions. We describe in detail the most relevant optical properties that make this material an attractive candidate for nonlinear frequency con- version of laser light in general, and ultrafast femtosecond laser sources in particular. With special focus on ultrafast frequency conversion, characteristics such as group-velocity mismatch and spectral acceptance, parametric gain bandwidth, group-velocity dispersion, as well as angular acceptance and spatial walk-off are evaluated and optimum configurations for the attainment of maximum conversion efficiency, minimum pulse duration, and highest spatial beam quality are identified and compared with the most widely established alternative borate crystal, β-BaB2O4. Experimental results are presented on both parametric up- and down-conversion of femtosecond pulses, from the high-energy, low-repetition-rate (1 kHz) to the low-energy, high-repetition- rate (56-76 MHz) regime, demonstrating the unique versatility of BIBO for efficient frequency conversion of femtosecond pulses with broad tunability from 250 nm in the UV, throughout the visible, up to ∼ 3000 nm in the IR. Photograph of a femtosecond synchronously pumped optical parametric oscillator (SPOPO) based on BiB3O6 emitting in the yellow region of the spectrum. Pumped near 400 nm in the blue by the second harmonic of a Kerr-lens mode-locked Ti:sapphire laser, the SPOPO can generate femtosecond pulses across the full visible range of 480-710 nm, from the blue-green, through to yellow, orange and red.

/pdf/femtosecond-nonlinear-frequency-conversion-based-on-bib3o6-3z7ng4rkvm.pdf

Femtosecond nonlinear frequency conversion based on BiB3O6

We discuss the main issues of optical parametric chirped pulse amplification and overview recent progress in the field. Although we distinguish between the two operating modes of modern chirped pulse parametric amplifiers, OPCPA and NOPA, we reveal that both represent the same technique and share a common concept.

Progress in Chirped Pulse Optical Parametric Amplifiers

A theoretical investigation is made of the tuning charactenstics and of the spectrum of an optical parametric oscillator with a quadratically nonlinear medium. Anomalous behavior of these characteristics is reported for a number of nonlinear crystals and it is attributed to the dispersion properties of these crystals. The observed anomalies can be used to generate wide-band picosecond radiation (continuum) in the infrared range, and also to form light pulses of duration amounting to a few femtoseconds.

http://iopscience.iop.org/article/10.1070/QE1983v013n09ABEH004675/pdf

Dispersion anomalies of tuning characteristics and spectrum of an optical parametric oscillator

A numerical analysis is made of the three-wave parametric interaction with the aim of finding anomalously wide frequency bands of eollinear amplification. A report is given of experimental attainment of collinear generation of 1-μ radiation with a spectral width ~3000 cm−1 in a superluminescent parametric oscillator utilizing a KDP crystal (oo–e interaction) pumped by the second harmonic of a phosphate glass picosecond laser. It is also reported that frequency doubling of this radiation in a KDP crystal can be used to generate wide-band (spectral width ~1000 cm−1) radiation in the region of 0.5 μ.

https://iopscience.iop.org/article/10.1070/QE1982v012n12ABEH006315/pdf

Parametric generation of picosecond continuum in near-infrared and visible ranges on the basis of a quadratic nonlinearity

A new technique is proposed to determine the fluctuations in the energy and duration of ultrashort radiation pulses. It is established that the duration of ultrshort radiation pulses from a YAG:Nd3+ laser is 28±5 psec.

Fluctuations of the energy and duration of Q-switched picosecond YAG:Nd3+ laser radiation

A theoretical analysis is made of the influence of fluctuations in the parameters of picosecond optical pulses on the determination of their duration from the autocorrelation function. It is shown that distortions of the autocorrelation function are governed by the degree of correlation between fluctuations of the duration and power of picosecond pulses. The variances of the fluctuations of the pulse power and duration, and also the degree of correlation between them were determined experimentally for radiation from a mode-locked YAG:Nd3+ laser.

Determination of the duration of fluctuating picosecond optical pulses

The results are given of theoretical and experimental investigations of the conversion of the pump statistics by three-wave parametric amplification of picosecond light pulses under strong energy-exchange conditions. A study is made of the influence of fluctuations of the pump radiation on the parametric conversion efficiency.

A Birmontas

Papers

Dispersion anomalies of tuning characteristics and spectrum of an optical parametric oscillator

Parametric generation of picosecond continuum in near-infrared and visible ranges on the basis of a quadratic nonlinearity

Fluctuations of the energy and duration of Q-switched picosecond YAG:Nd3+ laser radiation

Determination of the duration of fluctuating picosecond optical pulses

Conversion of the statistics of picosecond light pulses in a parametric amplifier under strong energy exchange conditions