Selectable Dual-Wavelength Actively Q-Switched Laser by Monolithic Electro-Optic Periodically Poled Lithium Niobate Bragg Modulator

A novel dual-wavelength actively Q-switched laser by a cascaded electrooptic periodically poled lithium niobate (PPLN) Bragg modulator has been developed. Two PPLN Bragg modulators with grating period Λ₁ = 20.3 (EPBM1) and Λ₂ = 25.7 μm (EPBM2) are integrated monolithically and used to separately Q-switch the transitions between ⁴F_3/2 → ⁴I_11/2 and ⁴F_3/2 → ⁴I_13/2 at the same Bragg angle. When applying 20-W diode power and 1-kHz Q-switching rate, the output wavelength can be selected between 1063 and 1342 nm with the peak power values of 27.6 and 1.6 kW, respectively. Utilizing two LBO crystals and an intracavity frequency doubling configuration, the green and red lasers can be selectively generated with the peak power values of 19 and 0.183 kW, respectively. The coupling effect between two PPLN Bragg modulators can be further reduced by adopting a longer EPBM1 and enhancing the performance of ⁴F_3/2 → ⁴I_13/2 at the high pump power region.