Discretely tunable, all-solid-state laser in the green, yellow, and red

Abstract

We report an all-solid-state intracavity Raman laser with intracavity nonlinear sum-frequency generation providing visible output wavelengths selected from second harmonics and sum frequencies of the fundamental and Stokes fields. The laser comprises a diode end-pumped Nd:YAG laser, an acousto-optic Q switch, a KGd(WO4)2 Raman crystal, and a lithium borate nonlinear converter in a resonator designed to accommodate dynamic thermal lensing. For 20 W of pump power, output powers up to 1.8 W are demonstrated at wavelengths of 532, 555, 579, and 606 nm, selectable by angle and temperature tuning of the nonlinear medium.

Wavelength-versatile visible and UV sources based on crystalline Raman lasers

“…Lower output powers were obtained at longer wavelengths, because both the resonator mirrors were 20-30% transmitting at the second-Stokes wavelength (1273 nm). We also found that the powers generated at the sum frequencies were lower than that at the second harmonics [57].…”

“…To our knowledge, wavelength-selectable lasers based on intracavity SHG/SFG of intracavity Raman lasers have been reported only by Ammann [14,62] and ourselves [57,69].…”

“…A 10 mm-long LBO crystal was used in Ref. [57], cut for critical phase matching of the 1158/579 nm interaction. Output at 579 nm was obtained near normal incidence, and outputs at 555 and 579 nm were achieved by rotating the crystal through an angle of approximately 111 and 171, respectively, followed by realignment of the output mirror.…”

“…Temperature tuning: For temperature tuning across four visible wavelengths [57], two 10 mm-long LBO crystals were used, each with an independent temperature controller. Crystal LBO1 was cut for non-critical phase matching (y ¼ 901, j ¼ 01), while crystal LBO2 was cut for critical phase matching of the 1064/532 nm interaction at 25 1C.…”

“…More recently, Mildren et al [57] and Li et al [58] used diode-pumped, Q-switched Nd:YAG systems, with separate crystals for the Raman and frequency-mixing processes to achieve high overall conversion efficiencies (diode-yellow $8%) and visible output powers over 3 W. This arrangement also permits a wider choice of Raman and frequency-mixing materials and therefore output wavelengths. However, the early work by Ammann is very significant in terms of showing the potential for achieving a diversity of output wavelengths from a laser incorporating both SRS and nonlinear frequency mixing.…”