Efficient Dual-Wavelengths Continuous Mode Lasers by End-Pumping of Series Nd:YVO4 and Nd:GdVO4 Crystals and Speckle Reduction Study

Abstract

In this paper, diode pumped solid state (DPSS) lasers based on end-pumping series N d : Y V O 4 and N d : G d V O 4 crystals were studied. Dual-, tri-, and quad-wavelength emissions were achieved. In the dual-wavelength emission operation, an optical-to-optical efficiency (O-O) of 48.9% and the power instability was 0.4% were obtained. These are the most efficient and compact lasers operating in continuous wave mode reported to date with series crystals. Besides this, the effect of changing power ratio between the output laser powers on speckle reduction was investigated for the first time. In addition, tri and quad wavelength emissions were achieved with a reasonable efficiency simply by optimizing the cavity parameters.

A passively Q-switched dual-wavelength laser with pulsed LD coaxial end-pumped configuration

“…Dual-wavelength lasers are of great interest in wide applications such as terahertz generation, biomedicine, precision measurement and spectroscopy [1][2][3][4]. Based on the transitions between different energy levels or Stark sublevels, direct laser emission with two wavelengths from one laser crystal or two separately pumped laser crystals sharing part or the whole cavity is a conventional method for dual-wavelength generation, the latter of which is much more stable and the power ratio can be tuned by varying the pump power at the expense of a complex cavity and additional pump sources [5][6][7][8][9][10]. For the case of dual-wavelength generation in a single laser crystal, there are strict requirements for cavity mirror coatings [11], and as different wavelengths usually originate from the same upper energy level [12,13], the inherent gain competition causes considerable power fluctuations for each wave.…”