Efficient single-axial-mode operation of a Ho:YAG ring laser pumped by a Tm-doped silica fiber laser

Unidirectional ring laser operation and tunable single-frequency emission using differential parametric gain

In this Letter, a novel approach for unidirectional operation of a 1064 nm solid-state ring laser is demonstrated based on difference frequency mixing. Unidirectional operation is achieved exploiting the directional parametric gain from a single-pass diode laser, facilitated through a periodically poled LiNbO3 crystal. In addition to achieving unidirectional operation, the nonlinear process further enables the generation of single-frequency mid-infrared light. Using a single-pass tapered diode laser, tunable in the range from 780 to 815 nm, the generated mid-infrared signal covers the 2.9 to 3.5 µm range while optimizing the phase-match condition of the difference frequency generation process.

High efficiency tunable unidirectional single-longitudinal-mode Er:YAG ring laser based on an acousto-optic modulator

A wavelength tunable single-longitudinal-mode (SLM) Er:YAG ring laser around 1.6 µm is demonstrated. By using an acousto-optic modulator (AOM) to force unidirectional operation, up to 10.4 W and 8.7 W SLM laser output power are obtained at 1645.22 nm and 1617.33 nm, with corresponding slope efficiencies of 45% and 40%, respectively. Besides, stable dual-wavelength operation at both 1645 nm and 1617 nm is also achieved with the maximum power of 9.1 W. By rotating the birefringent filter (BRF) in the ring cavity, the wavelength could be tuned from 1616.77 nm to 1617.51 nm and 1644.51 nm to 1646.12 nm. The line width is measured to be 125 kHz at 1617 nm and 131 kHz at 1645 nm via the time-delayed self-heterodyne method. As far as we know, 8.7 W is the highest continuous-wave SLM output power at 1617 nm.

High efficiency single-longitudinal-mode resonantly-pumped Ho:GdTaO4 laser at 2068nm

Based on Faraday effect we demonstrate a thulium fiber pumped continuous-wave single-longitudinal-mode laser with a new Ho:GdTaO₄ crystal. By inserting a faraday rotator and a half-wave plate into the laser cavity, the single-longitudinal-mode output power of 392 mW at wavelength of 2068.33 nm was obtained in unidirectional Ho:GdTaO₄ ring laser, corresponding to a slope efficiency of 60.2% respect to the absorbed pump power. Furthermore, utilizing the Ho:GdTaO₄ power amplifier, the maximum single-longitudinal- mode output power of 1.02 W was achieved.

Tunable single-longitudinal-mode Ho:YAG laser pumped by a 1.13 μm diode laser

We demonstrate a tunable single-longitudinal-mode Ho:YAG laser pumped by a 1.13 μm diode. With two intracavity Fabry-Perot etalons, the maximum single-longitudinal-mode output power of 102 mW at 2129.6 nm is obtained. The wavelength is tuned from 2119.7 to 2131.5 nm by precisely rotating two etalons. The measured beam quality factors M² are 1.29 and 1.28 in the x and y directions, respectively.

Unidirectional ring-laser operation using sum-frequency mixing

A technique enforcing unidirectional operation of ring lasers is proposed and demonstrated. The approach relies on sum-frequency mixing between a single-pass laser and one of the two counterpropagating intracavity fields of the ring laser. Sum-frequency mixing introduces a parametric loss for the intracavity field copropagating with the single-pass field, effectively generating a loss difference between the copropagating and counterpropagating intracavity fields. This loss mechanism ensures stable unidirectional lasing. The approach is generic and can be implemented at any desired lasing wavelength where lossless second-order nonlinear materials are available. Numerical modeling and experimental demonstration of parametric-induced unidirectional operation of a diode-pumped solid-state 1342nm cw ring laser are presented.

Midinfrared laser source with high power and beam quality

A simple scheme for generation of high power in the midinfrared is demonstrated. By using a 15 W thulium-doped fiber laser emitting at 1907 nm to pump a Q-switched Ho:YAG laser, we obtained 9.8 W at 2096 nm at a 20 kHz pulse repetition rate with excellent beam quality. The output of this laser was used to pump a doubly resonant zinc germanium phosphide based optical parametric oscillator, and we obtained 5.1 W average power in the 3-5 microm range with M2 approximately = 1.8.