Terahertz parametric generation and amplification from potassium titanyl phosphate in comparison with lithium niobate and lithium tantalate

Abstract

We report superior terahertz parametric generation from potassium titanyl phosphate (KTP) over congruent-grown lithium niobate (CLN) and lithium tantalate (CLT) in terms of parametric gain and laser damage resistance. Under the same pump and crystal configurations, the signal emerged first from KTP, 5% Mg-doped CLN, CLN, and then finally from CLT. The signal growth rate in KTP was comparable to that in 5%-Mg-doped CLN, but the signal power from KTP reached a much higher value after all the other crystals were damaged by the pump laser. We further demonstrate seeded terahertz parametric amplification in an edge-cut KTP at 5.74 THz. The THz parametric amplifier (TPA) employs a 17-mm long KTP gain crystal, pumped by a passively Q-switched pump laser at 1064 nm and seeded by a continuous-wave diode laser tuned to the signal wavelength at 1086.2 nm. With 5.8-mJ energy in a 520-ps pump pulse and 100-mW seed signal power, we measured 5-W peak-power THz output from the KTP TPA with 22% pump depletion. In comparison, we measured no detectable THz output power from a similar edge-cut CLN TPA under the same pump power, detection scheme, and crystal configuration, when tuning the seed laser wavelength to 1072.2 nm and attempting to generate a radiation at 2.1 THz.

Enhancement of Intracavity-Pumped Terahertz Parametric Oscillator Power by Adopting Diode-Side Pumped Configuration Based on KTiOPO4 Crystal

“…In recent years, researchers found that the KTP crystal could also be used to obtain THz radiation through the stimulated polariton scattering (SPS) effect [11][12][13][14]. SPS is a special frequency down-converting process which includes both second-order and third-order nonlinear effects [15].…”

“…The obtained THz pulse energy was 336 nJ at 5.72 THz when the pulse repetition frequency (PRF) was 10 Hz and the pump pulse energy was 80 mJ [11]. In the following years, there were some reports of enhancing the performance of the external cavity-pumped SPS laser using a KTP crystal [12][13][14]. The external cavity-pumped SPS sources are mainly used to generate terahertz pulses with relatively high pulse energy and low pulse repetition rate.Compared with the external cavity-pumped system which requires a high-pulse-energy pumping laser, an intracavity-pumped system, in which the nonlinear crystal is inserted in the fundamental cavity, can take advantage of the high intracavity fundamental power density to enhance nonlinear conversion.…”

Time-domain spectroscopy of KTiOPO4 in the frequency range 06–70 THz

“…using it's quasi-phase matching properties in optical parametric amplifiers [16,17], or as envisaged in [18], pumped with a dual wavelength fiber laser for direct THz conversion through the beat frequency [19]. Recently, THz generation using parametric amplification in KTP was observed [20], and very recently Wu et al demonstrated generation of >100 kW peak power from a KTP THz parametric oscillator [21].…”

Simultaneous Generation of Two Orthogonally Polarized Terahertz Waves by Stimulated Polariton Scattering with a Periodically Poled LiNbO3 Crystal

“…Stimulated polariton scattering (SPS) has proven to be an efficient scheme to generate terahertz (THz) waves [1][2][3][4][5][6][7][8]. A polariton is a coupled quantum between the pump laser and the infrared-and Raman-active transverse optical (TO) modes in a crystal, and it behaves like phonons near the resonant frequency associated with the TO mode and exhibits photon-like behavior for lower non-resonant frequencies [1].…”