Triple wavelength-switchable lasing in yellow-green based on frequency mixing of self-Raman operation

Abstract

An efficient Nd:YVO<sub>4</sub> crystal self-Raman laser combined with second-order nonlinear frequency conversion is demonstrated to achieve an switchable output of three wavelengths in the yellow-green band. In order to improve the thermal effect and increase the length of Raman medium, a three-stage diffusion-bonded YVO<sub>4</sub>/Nd:YVO<sub>4</sub>/YVO<sub>4</sub> crystal is designed for high power and efficient self-Raman laser operation. Selective frequency mixing mechanisms between the fundamental wave and the first Stokes wave using the LiB<sub>3</sub>O<sub>5</sub> (LBO) and BaB<sub>2</sub>O<sub>4</sub> (BBO) crystals are comparatively studied by temperature tuning and angle tuning, respectively. Considering the frequency mixing conversion efficiency and a relatively fast wavelength switching, the BBO crystal with critical phase matching is selected as the second order nonlinear optical crystal for frequency conversion. It only needs to fine-tune the phase match angle of BBO crystal within 1.4°, and thus successfully realizing all second harmonic and sum frequency generation between the fundamental wave and the first Stokes wave. Therefore the efficient-switchable output of the three wavelengths of 532 nm green light, 559 nm lime light and 588 nm yellow light is obtained. Under the incident pump power of 19.5 W and the pulse repetition rate of 60 kHz, maximum average output power of 4.37 W at 532 nm, 2.03 W at 559 nm, 3.43 W at 588 nm are achieved. The conversion efficiency values of the corresponding pump light to visible light are 22.4%, 10.4% and 17.6%, respectively. The corresponding pulse widths are 36 ns, 12.2 ns and 12.7 ns, respectively. The results show that the selective frequency mixing of self-Raman operation is an efficient approach to achieving the wavelength-switchable emission in visible waveband. This wavelength-switchable laser source has important applications in the areas of laser therapy, visual display, spectral imaging and biological medicine.

Compact 589 nm yellow source generated by frequency‐doubling of passively Q‐switched Nd:YVO4 Raman laser

“…Nd:YVO 4 crystal using for self-Raman operation has attracted increasing attention in recent years, which performs laser gain and Raman conversion functions simultaneously. [1][2][3][4] Through frequency doubling of its first Stokes wave is also an important approach to achieve yellow emission [5][6][7] with significant application in medical treatment, laser display, remote sensing and metrology. [8][9][10][11][12] Especially for second harmonic generation (SHG) of the c-cut Nd:YVO 4 crystal Raman laser, it could achieve 589 nm yellow emission for potential sodium beacon application as its resonating with sodium D 2 spectrum line.…”

The single‐wavelength 561 nm laser based on reflective volume Bragg grating

“…[14][15][16][17][18] At present, there are two main methods for realizing all-solid-state 561 nm single-wavelength laser. One is generated by sum-frequency generation of Nd:YVO 4 self-Raman laser, 19,20 and the other is obtained by intracavity frequency doubling of Nd:YAG. In the process of intracavity frequency doubling, since the three spectral lines of fundamental frequency light at 1112 nm, 1116 nm, and 1123 nm are too close, there would be simultaneous intracavity transitions and mode competition among them, which greatly affects the laser output power and stability.…”