Reverse-Wave Suppressor Mirror Effects on CW HF Unstable Ring Laser Performance,
Abstract
The effect of a reverse-wave suppressor (RWS) mirror on the performance of a CW HF unstable ring laser has been measured in terms of forward/reverse-wave power ratio (R) and forward-wave beam quality. It was found that a well-aligned RWS mirror gave the best suppression R = approx. 100 and diffraction-limited beam quality. Resonator performance degraded rapidly with misalignment of the RWS mirror: a 200-microrad tilt reduced R to 2.5 and the beam quality by a factor of 2. The forward-wave near-field pattern showed distinct fringes as the RWS mirror was misaligned, suggesting that a higher-order mode was causing the beam quality to degrade. A novel technique was developed to reduce the alignment sensitivity of the RWS mirror. By use of a distorted relay mirror, an aberrated (approx. = 2 lambda) reverse wave was fed back into the ring. The aberrated reverse-wave feedback greatly reduced the sensitivity of resonator performance to RWS mirror tilt. Diffraction-limited beam quality and good suppression (R = approx. 20) was observed over a tilt range of 600 microrad. It is postulated that the aberrated RWS mirror provides sufficient feedback to suppress the reverse wave over a wide angular range, yet not enough to produce higher-order transverse modes in the forward wave.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1985
- Accession Number
- ADA163529
Entities
People
- Harold Mirels
- Jay M. Bernard
- Richard A. Chodzko
Organizations
- The Aerospace Corporation