Gordon Robertson

Continuous-wave singly resonant pump-enhanced type II LiB(3)O(5) optical parametric oscillator.

We report what is to our knowledge the first demonstration of a pump-enhanced singly resonant continuous-wave optical parametric oscillator. The nonlinear material used was lithium triborate cut for noncritical phase matching along the z axis, and the device was pumped by a single-frequency argon-ion laser. The oscillation threshold was ~1.0 W at 514.5 nm. For 3.4 W of pump power, we obtained single-frequency output powers of 500 mW in the nonresonant wave, which we temperature tuned over 14 nm.

Efficient ultraviolet LiB 3 O 5 optical parametric oscillator

We report what is to our knowledge the first optical parametric oscillator (OPO) generating coherent laser radiation with high optical-to-optical conversion efficiency in the near ultraviolet. The OPO, pumped at 307.8 nm by a pulsed injection-seeded XeCl excimer laser, employs a crystal of LiB(3)O(5) in a noncritical phase-matching geometry to generate tunable output over the range 381-387 nm in the near ultraviolet and 1.5-1.6 microm in the near infrared. We report internal energy conversion efficiencies as high as 28% for the signal wave at 385.5 nm and 7% for the idler wave at 1.53 microm, leading to a total internal conversion efficiency of 35%. Studies of oscillation threshold, external and internal conversion efficiency, spectral linewidth, and temporal variation of output pulses are also reported. Temperature tuning of the LiB(3)O(5) OPO under the noncritical phase-matching condition is demonstrated for the first time to our knowledge.

Broadly tunable LiB3O5 optical parametric oscillator

We report, what is to our knowledge, the first XeCl excimer pumped optical parametric oscillator using critical phase matched LiB3O5 (LBO), to generate broadly tunable coherent radiation with high optical to optical efficiency. Tuning ranges of 355–497 nm in the ultraviolet/blue spectral region, and 809–2.34 μm in the near‐infrared have been obtained, with pump depletions as high as 28%. Oscillation thresholds, external efficiencies, effects of intracavity losses, effects of pump beam size and inherent linewidths (∼0.3 nm) are also reported.

Comparison of lithium triborate and β-barium borate as nonlinear media for optical parametric oscillators

We compare the relative merits of the new nonlinear materials β-barium borate and lithium triborate for use as gain media in singly resonant pulsed optical parametric oscillators pumped by either excimer lasers or frequency-upconverted diode-laser-pumped solid-state lasers. Lithium triborate is the material of choice when one requires low-pump-energy threshold devices ( 100 mJ) that are associated with excimer lasers.

Attainment of high efficiencies in optical parametric oscillators

Major practical requirements relevant to achieving high conversion efficiencies in optical parametric oscillators have been identified. In particular, an experimental comparison has been made between critically and noncritically phase-matched geometries in beta-barium borate (BBO) and lithium triborate (LBO), respectively, when they are pumped by an excimer laser at 308 nm. We report pump depletions of 40% in LBO and 50% in BBO when 385- and 1540-nm radiation is parametrically generated. Pump depletions of 64% have been obtained in BBO when 540- and 700-nm radiation is generated. Optimization of external efficiencies has been studied, and values of 30% have been obtained in LBO by resonating the low-energy wave.

Efficient, single‐axial mode oscillation of a beta barium borate optical parametric oscillator pumped by an excimer laser

Intracavity etalons have been used to obtain single axial mode oscillation of a beta barium borate optical parametric oscillator pumped at 308 nm by a XeCl excimer laser. Two high finesse etalons were sufficient to select a single axial mode of the resonant signal wave over a tuning range 400–560 nm with the increase in oscillation threshold due to etalon insertion being kept below 1.5 times. Addition of a grating enabled single axial mode oscillation to be maintained out to degeneracy (616 nm).

Excimer pumped deuterated L‐arginine phosphate optical parametric oscillator

The first optical parametric oscillator (OPO) using deuterated L‐arginine phosphate is reported herein. The OPO pumped at 308 nm by an XeCl excimer laser generates broadly tunable output over the spectral ranges 415 to 526 nm and 1194 to 743 nm, using a critically phase‐matched type I geometry. A study of the oscillation threshold has been made under conditions of different beam sizes and across the tuning range. A discussion of the damage problem in the material and the implications of 351 nm pumping are also given.