Temperature insensitive, high-power cascaded optical parametric oscillator based on an aperiodically poled lithium niobate crystal

Abstract

We report a novel temperature insensitive, APMgLN-based, high-power cascaded optical parametric oscillator (OPO) pumped by an Ytterbium-doped fiber laser. A monolithic APMgLN crystal was designed to compensate the phase mismatches for the nonlinear conversions from the pump to the idler and the primary signal to the idler simultaneously in a wide temperature range. Efficient parametric conversion with pump-to-idler conversion efficiency over 15% and slope efficiency higher than 20% was realized from 25 °C to 55 °C. The idler wavelength was down-shifted from 3.82 μm to 3.78 μm accordingly during the temperature rise. The highest idler power of 4.1 W at 3.8 μm under the pump power of 26.5 W was recorded which was improved by ~32% in pump-to-idler conversion efficiency when compared with the PPMgLN-based conventional OPO, in which the highest idler output power was 3.1W under the same pump and thermal condition.

Optimization of the idler wavelength tunable cascaded optical parametric oscillator based on chirp-assisted aperiodically poled lithium niobate crystal

“…In the simulation, the pump pulse energy is selected to be 350 µJ according to the typical parameters of fiber lasers reported in other fiber-laser-pumped OPO systems. [19,23] In the scenario of zero idler wavelength tuning range, the maximum pump-toidler conversion efficiency of 32% is achieved under the pump pulse duration of 180 ns when the ratio of OPO coefficient to DFG coefficient is 1.5. When the idler wavelength tuning range is extended to 65 nm, the highest pump-to-idler conver-sion efficiency decreases down to 25% with the ratio of OPO coefficient to DFG coefficient slightly upshifted to 1.6 and the most suitable pump pulse duration shortened to 90 ns.…”

“…These values were selected according to the available coating parameters of single pass singly resonant (SPSR) operated cascaded OPOs. [19,23] pump laser isolator L1 M1 M2 M3 APMgLN M3 was a high pass filter blocking the residual pump, the primary and secondary signal waves for independent wavelength and power measurement of the desired idler wave.…”

“…As a better alternative, a specially designed aperiodically poled magnesium oxide doped lithium niobate (APMgLN) crystal with a chirp parameter for the DFG process was proposed to increase the thermal acceptance bandwidth. [23] Consequently, the idler wavelength could be tuned by the crystal temperature and the pump-to-idler conversion efficiency could be improved by the secondary DFG process within the thermal acceptance bandwidth. However, the relative strength of the two simultaneously phase matched processes and the idler wavelength tuning ranges were fixed in the previous experiment.…”

High Conversion Efficiency, Mid-Infrared Pulses Generated via Burst-Mode Fiber Laser Pumped Optical Parametric Oscillator

“…Hence, improvement in the pump-to-idler conversion efficiency can be obtained. In this aspect, we have already investigated an efficient OPO with high parametric conversion from 1.064 to 3.8 µm [18], [19]. A quasi-periodically poled magnesium oxide doped lithium niobate wafer was designed and fabricated as the nonlinear crystal of the OPO.…”

“…A quasi-periodically poled magnesium oxide doped lithium niobate wafer was designed and fabricated as the nonlinear crystal of the OPO. When compared with a periodically poled channel fabricated on the same wafer, an improvement of 32% in conversion efficiency was realized for the pumpto-idler conversion [19].…”