Polarization control of dual‐wavelength high peak power Raman lasers based on passively Q‐switched technology and yttrium vanadate (YVO4) crystal are widely used for generating novel laser sources, terahertz wave, material processing, and manipulating microparticles. However, the Raman lasers are usually linear polarization. Here, elliptical polarizations with controllable ellipticity and azimuthal angle are manipulated by adjusting the crystalline orientation of a‐cut YVO4 crystal in a passively Q‐switched Raman laser constructed with a Cr4+,Nd3+:Y3Al5O12 (Cr,Nd:YAG) crystal and a a‐cut YVO4 crystal. The ellipticity of the elliptically polarized dual‐wavelength Raman laser varies in a sinusoid modulation as a‐cut YVO4 crystal rotates with respect to the major axis of the intracavity fundamental laser and increases with applied pump power. The azimuthal angle varies in the same speed as a‐cut YVO4 crystal rotates. Anisotropic behavior of sinusoidal modulation of output power, pulse energy, and peak power is observed as a‐cut YVO4 crystal rotates. There are four peaks and four troughs for ellipticity, output power, pulse energy, and peak power within a 360° rotation of a‐cut YVO4 crystal. This work provides a solid and simple method for developing elliptical polarization controllable dual‐wavelength passively Q‐switched Raman laser with high peak power for various potential applications.

Elliptically polarized high peak power two‐color lasers have potential applications on material science, biology, optical detection, and terahertz wave generation. Two‐color pulsed lasers with flexible power intensity ratio are essential for analyzing material properties, however, control of power ratio between two lasers is a challenge for developing compact passively Q‐switched (PQS) solid‐state laser. Here, taking advantage of Nd:YAG/Cr4+:YAG composite crystal and a‐cut YVO4 crystal, a PQS Raman microchip laser is developed for generating a two‐color Raman laser with tunable power intensity ratio between two Raman lasers and elliptical polarization. Power intensity ratio tuned from 1 to 0 between 1166 nm Raman laser and 1166/1176 nm two‐color laser is achieved by adjusting a‐cut YVO4 crystalline orientation. State of polarization of Raman laser is elliptical polarization. The ellipticity is flexibly tuned from 0.3 to 0.91 by adjusting pump power and a‐cut YVO4 crystalline orientation. The Raman laser pulses with peak power of 6.4 kW and pulse width of 1.5 ns are obtained. The synchronized Raman laser pulse repetition rate is 14.3 kHz. This work enables development of a compact high peak power two‐color Raman laser with flexible control of power intensity ratio between two color lasers in a diode pumped PQS Raman microchip laser.