High repetition rate and high power picosecond terahertz parametric amplifier with a KTiOPO4 crystal

Abstract

A high repetition rate, high power, and widely tunable THz parametric amplifier (TPA) with a KTiOPO4 crystal has been demonstrated in this work. A peak power of 1.7 kW and an average power of 89 μW have been obtained at a frequency of 5.74 THz and a repetition rate of 10 kHz. The radiation is expected to be Fourier transform limited, with a pulse duration (full width at half maximum, FWHM) of 5.4 ps and a bandwidth (FWHM) of 81 GHz, and has an M2 parameter close to the pump laser. We have also tested the TPA at a repetition rate of 100 kHz, and the results indicate that mW-level (average power) THz radiation output is feasible with a stronger pump laser that is commercially available.

Continuously Tunable and Energy-Enhanced Injection Pulse-Seeded Terahertz Parametric Generator Based on KTP Crystal

“…Thus, for a certain polariton, its ability to generate THz wave depends on the joint action of the ratio of radiative energy and the value of absorption. For the reported THz parametric sources using a KTP crystal, ,, the THz generation was located in the frequency range where the P rad is relatively large and the THz absorption coefficient is small. Besides, the several THz wave emission windows for the KTP TPOs are induced by those two factors.…”

“…LN family crystals contain congruent LN (CLN), MgO-doped congruent LN (MgO:CLN), MgO-doped near-stoichiometric LN (MgO:SLN) crystals, which possess only one polariton in the THz region . Therefore, limited by the phase matching conditions of the SPS process in the TPO/TPG systems based on LN family crystals, the typically continuous THz frequency tuning range with high output energy were located between 1.4 and 2.5 THz. − As for KTP family crystals, including KTiOPO 4 (KTP), KTiOAsO 4 (KTA), and RbTiOPO 4 (RTP) crystals, the THz tuning ranges from 1 to 13 THz, except for several gaps that have been successfully achieved in TPOs by using the multiple polaritons located in a wide THz region. − However, the THz output energies of KTP TPOs were typically at least 1–2 orders of magnitude lower than that of LN TPOs. ,,− Although some constructive efforts have been made to improve the output of the THz parametric source using KTP family crystals in recent work, the issue of tuning gaps remains unsolved. , Moreover, this kind of discontinuity in THz tuning ranges is always simply recognized as the increases of the THz wave absorption near the eigenfrequencies of A1 modes . In general, current THz parametric sources based on KTP family crystals are still restricted to the tuning gaps and relatively low output energy, despite their wide THz tuning range, which greatly limits its applications in terahertz spectrum.…”

Cascaded Stimulated Polariton Scattering in a Single-Pass KTP Crystal under Picosecond Pumping

“…Intermittent tuning of the signal and THz waves in the process of the angle θ tuning was interpreted as the result of stimulated polariton scattering (SPS). To achieve relatively intense generation of the signal and consequently THz waves with a sufficiently narrow spectrum, a seeding radiation of an external tunable diode laser was injected into LiNbO 3 [2,11] and KTP [12] crystals in a version of THz sources without polariton cavity.…”

Intense luminescence emission and lattice damage of the implanted Eu ions in KTiOPO4 crystals

“…The KTP crystal has received extensive attention in many fields, such as industrial, medical and optical waveguide devices 1 – 4 Among the divalent lanthanides, Europium (Eu) has drawn huge attention because of the stability of the semi-filled 4f orbital, which making the divalent state easier to approach 5 – 7 The intense emission near the 612 nm caused by the internal D05–F27 transition of Eu has particular interest in GaN and SiO2 research 8 , 9 .…”