16.9 MW, efficient 486.1 nm blue optical parametric oscillator using single BBO crystal

Abstract

A single-resonant beta barium borate crystal optical parametric oscillator with high pulse energy output at the H-β Fraunhofer line of 486.1 nm was demonstrated. Pumped by a single-frequency 355 nm ultraviolet pulsed laser at 10 Hz repetition rate with maximum pulse energy of 411 mJ, maximum output energy of 162 mJ blue laser pulse at 486.1 nm was successfully obtained from a plano-concave cavity with a 40% output coupler, the corresponding optical-to-optical conversion efficiency was up to 39.4%, and the pulse width was around 9.6 ns. The blue laser beam size was 4.4 mm × 5.1 mm with the beam divergence angles of θx = 2.2 mrad and θy = 2.5 mrad. The peak power of output blue laser was 16.9 MW, and the signal linewidth was around 0.34 nm.

486 nm pulsed Nd:YLF laser with intracavity sum-frequency mixing

“…When 8.82 mJ total fundamental laser energy was applied, the cumulative spectrum was recorded during 2 min, which already contained the output wavelength stability. The central laser wavelength was measured to be 486.4 nm with the spectral bandwidth of 0.08 nm, much less than the typical spectral bandwidth of around 0.3 nm obtained by the OPO method [1,3], as shown in figure 3. According to formula (1), the laser wavelength λ 3 generated by sum-frequency can be given by…”

“…Compact solid-state pulsed lasers operating at 486 nm have been extensively applied in ocean detection lidar and underwater communication [1][2][3]. The blue laser in the region of 470-490 nm is well suitable for the open ocean applications due to its quite high transmission in deep seawater [4].…”

“…By now, optical parametric oscillator (OPO) is the most common way to generate high power blue laser pulse. In an OPO cavity with BBO crystals, pumped by 355 nm ultraviolet pulsed laser, 486 nm blue pulsed laser can be obtained [1][2][3]. However, the 355 nm pulsed laser was not emitted directly from the laser gain crystal, and was generated by frequencytripling of the fundamental laser at 1064 nm.…”

High efficiency, low threshold, high repetition rate H-β Fraunhofer line light at 486.1 nm generation by an intracavity frequency-doubled optical parametric oscillator

“…In 2021, Zhang et al reported a BBO-OPO pumped by 355 nm laser with a PRF of 10 Hz. The maximum output energy at 486.1 nm was 162 mJ, with the conversion efficiency of 39.4% [23] . The high-energy 486.1 nm blue sources reported above have important value in ocean lidar and underwater detection applications.…”