Improving the efficiency of an optical parametric oscillator by tailoring the pump pulse shape

Abstract

The conversion efficiency of an optical parametric oscillator is reduced by energy consumption during build-up of signal and idler intensities and due to back-conversion effects. By tailoring the pump pulse temporal shape, we are able to improve the conversion efficiency by minimizing build-up time and back-conversion. Simulations predict a significant improvement in 1064 nm to 4000 nm idler conversion by using a double-rectangular temporal shape rather than using a simple Gaussian pulse. Experimental results qualitatively verify the effect resulting in a 20% improvement of a rectangular pulse over a Gaussian pulse.

High-power PPMgLN-based optical parametric oscillator pumped by a linearly polarized, semi-fiber-coupled acousto-optic Q-switched fiber master oscillator power amplifier

“…According to these requirements, fiber lasers are supposed to be the best candidates among all the OPO pump sources due to their compactness, robustness, excellent beam quality, and simple thermal management schemes [3]. Therefore, fiber-laser-pumped OPOs have been extensively investigated from continuous wave (CW) to ultrashort pulsed operation schemes [4][5][6][7][8][9][10][11][12][13]. Among all these pump sources, fiber lasers with tens to hundreds of nanoseconds are particularly useful in outdoor applications for both environmental monitoring and missile countermeasures because simple linear cavities are applicable to such pump sources converting the pump power to idler output efficiently during each pulse with peak power higher than the CW OPOs and dimensions smaller than the synchronously pumped OPOs.…”

“…Among all these pump sources, fiber lasers with tens to hundreds of nanoseconds are particularly useful in outdoor applications for both environmental monitoring and missile countermeasures because simple linear cavities are applicable to such pump sources converting the pump power to idler output efficiently during each pulse with peak power higher than the CW OPOs and dimensions smaller than the synchronously pumped OPOs. Consequently, many experiments have been carried out on linearcavity-structured OPOs pumped by master oscillator power amplifier (MOPA) configured fiber lasers working in the nanosecond region so far [9][10][11][12][13].…”

Improved idler beam quality via simultaneous parametric oscillation and signal-to-idler conversion

“…Furthermore, other methods to suppress back-conversion, e.g., by shaping the pump pulse [25], are also expected to improve the idler beam quality.…”

An all-fiber PM MOPA pumped high-power OPO at 3.82 μm based on large aperture PPMgLN

“…The ASE at 1040 nm and the stimulated Raman scattering (SRS) at 1115 nm were 25 dB and 40 dB lower than the signal peak respectively at the highest operating peak power. Although in principle it is helpful to use a shaped pulse with a relatively strong peak power close to the leading edge in order to reduce the OPO threshold [14], we found when trying this experimentally that the OPO conversion efficiency was not improved when the overall pump power (and peak power) was high. Accordingly to preserve the spectral integrity and minimize SRS without compromising the pulse energy, the initial pulses were pre-shaped to obtain square output pulses from our MOPA system.…”