Abstract
A passively Q-switched dual-wavelength laser with tunable power ratio and pulse interval is demonstrated based on the coaxial diode end-pumping configuration by varying the pump wavelength. A theoretical model was built by a set of time-domain rate equations illustrating the dynamic process of both the pulse generation of two wavelengths from a shared pump source and a saturable absorber. The simulation showed that both the power ratio and the time interval between the pulses at two resonant wavelengths in the Q-switched mode could be tuned by balancing the gains in two laser crystals by varying the pump wavelength, realized by controlling the working temperature of the pump laser diode. The experiment was performed with Nd:YAG/Nd:YAP composite laser crystals and a Cr4+:YAG slice working as the saturable absorber for pulse generation. The continuous-wave and Q-switched total output power reached 5.62 W and 2.12 W, corresponding to overall optical-optical conversion efficiencies of 37.5% and 14.1%, respectively. The manipulation of power ratio and pulse interval between 1064 nm and 1080 nm agreed well with the simulation results.
Highlights
PULSED dual-wavelength lasers are of great interest in applications such as terahertz generation, remote sensing, precision measurement, and spectroscopy [1]-[4]
The laser diode (LD) temperature was tuned to be 31 °C (804.2 nm) and the pump focusing position was at z = −1 mm, in order to balance the gains in two laser crystals at the maximum incident pump power of 15 W
The characteristics of a coaxially end-pumped passively Qswitched dual-wavelength laser were studied both in theory and experiment
Summary
PULSED dual-wavelength lasers are of great interest in applications such as terahertz generation, remote sensing, precision measurement, and spectroscopy [1]-[4]. A laser diode (LD) end-pumping configuration with coaxial arranged two laser crystals was proposed for dualwavelength laser generation [16]. It intrinsically eliminates gain competition and provides the possibility to tune the power ratio without any extra elements. To improve the laser stability, the pump absorption can be adjusted by varying the temperature-dependent pump wavelength, which requires no mechanical change to the cavity [18], [19]. By varying the pump wavelength to change the gains in two laser crystals, the power ratio between two laser wavelengths could be tuned and their pulse interval was adjustable in the Qswitched mode.
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