Coating-Less Non-Planar Ring Oscillator Laser

The Coating-Less Non-Planar Ring Oscillator Laser utilizes a monolithic laser crystal, whose surfaces are precisely polished to form an optical cavity within the crystal, solely using total internal reflection (TIR). All surfaces of the laser use TIR, eliminating the need for any optical coatings. Frustrated TIR (FTIR) is used for the outer surface. The output coupler satisfies TIR, as does other reflection surfaces, which has a large enough angle of incidence for the internal ray. The ring resonator of the laser is also designed to be nonplanar, meaning the optical path is not on a flat plane. The Coating-Less Non-Planar Ring Oscillator Laser achieves high stability, high output power, and high reliability both in continuous wave mode and pulsed mode. It does not use any thin film optical coatings. Since there are no thin-film optical coatings in the laser cavity, one can expect more reliable laser operation and higher output power. Also, since it has a traveling wave cavity with internal polarization rotation mechanism (through the non-planar optical path), the output mode is ensured to be single longitudinal mode and stable. It also eliminates the possibility of damage due to the transition between the multi-mode and single-mode oscillation. A traditional NPRO crystal may be used as the laser crystal. Coupling of the FTIR can be adjusted to make an air-gap cube beam splitter, where the distance between the two surfaces determines the FTIR coupling strength. The laser crystal can be used both for Q-switching and continuous mode.