Controllable continuous-wave dual-wavelength operation of in-band diode-pumped Nd:GdVO4/Nd:YVO4 composite laser
Date
2019
Authors
Onyenekwu, Chinedu
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Abstract
This thesis presents a controllable continuous-wave dual-wavelength diode-pumped laser based on a composite Nd:GdVO4/Nd:YVO4 crystal. Controllability for the pair of spectral output was achieved by changing the operating temperature of the fiber-coupled laser diode pump using a digital temperature controller. The resulting temperature-dictated pumping wavelength provided a precise and turnkey means of intensity control for the two emitted spectral lines as either line showed strong and proportionate intensity change in response to the wavelength of excitation by the pump. The intensity ratio for the pair was in favor of the GdVO4 emission at 1063 nm while pumping at about 912 nm while the YVO4 emission was relatively lower and vice versa while pumping at 914 nm. For power scalability, a low-quantum defect (QD) approach was adopted using in-band pumping. This was specifically performed around the 910 - 914 nm wavelength range considering and corresponding to the longer Nd:GdVO4/Nd:YVO4 absorption bands. Using this efficiency-increasing initiative, the laser produced a maximum output power of 4.48 W with 11.55 W of absorbed power, corresponding to a slope and optical-to-optical efficiency of 43.8 % and 38.8 % respectively. These parameters are notably the highest ever reported compared to all previous works using a similar composite crystal for dual wavelength operation.
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Dual-wavelength (DW) laser