Picosecond difference-frequency-generation in orientation-patterned gallium phosphide

Abstract

Abstract:We report the generation of tunable high-repetition-rate picosecond radiation in the mid-infrared using the new quasi-phase-matched nonlinear material of orientation-patterned gallium phosphide (OP-GaP). The source is realized by single-pass difference-frequencygeneration (DFG) between the output signal of a picosecond optical parametric oscillator (OPO) tunable across 1609-1637 nm with input pump pulses at 1064 nm in OP-GaP, resulting in tunable radiation across 3040-3132 nm. Using a 40-mm-long crystal, we have generated up to 57 mW of DFG average power at ~80 MHz repetition rate for a pump power of 5 W and signal power of 0.9 W, with >30 mW over >50% of the tuning range. The DFG source exhibits a passive power stability better than 3.2% rms over 1 hour in good spatial beam quality. To the best of our knowledge, this is the first picosecond frequency conversion source based on OP-GaP.

Long-wave infrared generation from femtosecond and picosecond optical parametric oscillators based on orientation-patterned gallium phosphide

“…The pump laser used was an 80-MHz modelocked laser with 8.5-ps pulses at 1064 nm (0.7-nm FWHM) producing an average output power of up to 5 W. The OPGaP crystals used were 23.9 mm in length with a grating period of 29 µm. We observed 70% transmission at the pump wavelength (yielding an absorption coefficient of 0.15 cm − 1 ), consistent with the absorption loss observed by Casals et al [29]. A ring cavity with 200-mm radius-of-curvature mirrors was configured to match the repetition rate of the pump laser.…”

“…At a wavelength of 1064 nm, the linear absorption of gallium phosphide should be low, though significant linear absorption was observed by Casals et al in their OPGaP experiments [29]. They reported only 52% transmission at 1064 nm through a 40-mm OPGaP crystal with a 16-µm grating period.…”

“…Difference-frequency mixing using OPGaP with both nanosecond and picosecond pump pulses at 1-µm wavelength has been explored [28,29], as well as with a continuous-wave pump [32] (as discussed in the introduction). At a wavelength of 1064 nm, the linear absorption of gallium phosphide should be low, though significant linear absorption was observed by Casals et al in their OPGaP experiments [29].…”

“…DFG and optical parametric generation (OPG) have been demonstrated with nanosecond and picosecond pulse 1-µm lasers [28][29][30], but the mid-IR wavelengths generated were around 3 µm, which fails to take advantage of OPGaP's transparency range up to 12 µm. DFG between continuous-wave lasers was used to generate 3.40 µm [31] and 5.85 µm [32] in OPGaP.…”

Performance characterization of mid-infrared difference-frequency-generation in orientation-patterned gallium phosphide

“…The OPG was temperature-tuned across 1721-1850 nm in the signal and 2504-2787 nm in the idler, providing up to ~18 mW of the total average output power at 25 kHz repetition rate, with ~5 mW of the idler output power. Further, in the picosecond pulse regime, we demonstrated a single-pass DFG source by mixing the output signal of a picosecond OPO and ~20 ps pump pulses from a mode-locked Yb-fiber laser at 1.064 μm in OP-GaP, providing tunable DFG output across 3040-3132 nm with up to 57 mW of average power at 80 MHz repetition rate [18]. On the other hand, in the continuous-wave (cw) regime, single-pass DFG based on 16.5-mm-long OP-GaP crystal was reported, providing up to 150 mW of output power at a fixed wavelength of 3400 nm for an input pump power of 47 W at 1.064 μm, together with 24 W of signal power at 1550 nm [19].…”