Coating-Less Non-Planar Ring Oscillator Laser
Coating-Less Non-Planar Ring Oscillator Laser (GSC-TOPS-254)
A compact laser that does not require any special optical coatings to enable a low phase noise, single frequency laser
There is a need for a single-frequency, single-mode, highly-stable laser. High optical power is desirable as a continuous-wave seed laser for interferometric applications and as a pulsed (Q-switched) oscillator for lidar applications. Laser induced damage on optical coatings is the most common catastrophic failure mechanism in high power lasers. The coating within the laser cavity is usually the most susceptible due to high intra-cavity fluence. Traditional non-planar ring oscillators (NPRO) require special dichroic coatings on the output surface of the laser crystal. Its damage limits the output power of the NPRO especially in the pulse (Q-switch) mode. Traditional Q-switch lasers based on multiple optical components also have many optical coatings within the laser cavity. The Coating-Less Non-Planar Ring Oscillator Laser minimizes the possibility of coating damages in order to build more reliable lasers.
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.
- Enables high performance due to high power
- Enables high reliability
- Laser manufacturing
- LIDAR applications