Waveguide laser

Details Waveguide laser Waveguide laser

1995-11-21

1997-11-04

Scott, Jr., Leon

Coherent light generators

Particular active media

Gas

372103, 372 98, 372 92, 372 19, H01S 303

Patent

active

056848200

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to a waveguide laser.
2. Discussion of Prior Art
Waveguide lasers are known in the part art. Such as laser typically consists of two mirrors (or equivalent reflecting devices) defining an optical resonator cavity, together with a waveguide defining at least part of an optical path between the reflectors. The waveguide has end apertures at or near which the reflectors are positioned respectively. The reflectors' radii of curvature and their positioning relative to the waveguide are related by the following Equations (1) and (2): to the respective nearest waveguide end aperture, which beam intensity is maximum and 1/e.sup.2 of maximum, beam measured at the respective neighbouring waveguide and aperture, and region between mirror and waveguide.
Equations (1) and (2) define a situation in which a mirror of radius R is phase matched to a TEM.sub.00 beam. Waveguide laser resonators have associated mirror configurations referred to in the prior art as Case I, Case II and Case III. They are defined with reference to Equations (1) and (2) above. They are described by J. J. Degnan and D. R. Hall, III, J Quantum Electron, Vol QE-9, pp 901-910, 1973. They are also referred to in "Theory of Waveguide Laser Resonators", Chapter 3 of "The physics and Technology of Laser Resonators", edited by D. R. Hall and P. E. Jackson, published by Adam Hilger. A Case I mirror has a large radius of curvature R (possibly infinite, ie a plane mirror) and a small or zero value of z; ie R tend to B.sup.2 /z in Equation (1) as z goes to zero. A Case II reflector has a large radius of curvature and is positioned such that z is approximately equal to R, B.sup.2 /z being negligible. Finally, a Case III reflector is one with z equal to about half the value of R, z being approximately equal to B and w.sub.0 being chosen to provide optimum coupling to the EH.sub.11 fundamental waveguide mode.
Waveguide lasers incorporating gas media are advantageous because the waveguide provides cooling for the discharge. As a result of gas discharge scaling laws, the waveguide also allows high pressure operation. Moreover, CO.sub.2 lasers in particular have a laser line width that increases with increased operating pressure, so incorporation of a waveguide improved potential tuning range. This also applies to other gas lasers in which laser line width increases with increasing pressure. A further potential advantage is that the gain medium of a waveguide laser may be confined to a small dimension optical waveguide, which makes it very compact compared with a free space resonator. Moreover, the resonator mode may effectively fill the waveguide, producing good overlap between the optical field and the gain medium. This results in efficient extraction of optical power. It is not necessarily the case in free space resonator designs.
However, waveguide lasers suffer from the disadvantage that the waveguides are difficult to fabricate with sufficient accuracy to obtain acceptable laser performance. A typical CO.sub.2 laser has an alumina (Al.sub.2 O.sub.3) waveguide in the region of 30 cm in length with an internal bore of square cross-section of side 2 mm. It is very difficult to fabricate an internal bore of these small dimensions accurately over the whole length of the waveguide. Uncertainty of cross-section leads to uncertainty of laser transverse mode characteristics. Waveguide lasers also suffer from the major disadvantage that they tend to run on unwanted higher order waveguide resonator modes rather than the fundamental resonator mode (usually near TEM.sub.00). This is particularly true for Case I designs. Case III is better in this respect, but it has an added disadvantage that it requires a concave mirror placed a much longer distance from the waveguide. Consequently, there is reduced effective power output per unit length of the laser compared to Case I.
In "Radio Frequency Excited CO.sub.2 Waveguide Lasers", Rev Sci Instrum 55 (1984), pp 1539-1541, R. L. Sinclair and J. Tulip d

REFERENCES:
patent: 3852684 (1974-12-01), Roess et al.
patent: 3961283 (1976-06-01), Abrams et al.
patent: 4287482 (1981-09-01), Wert, III
patent: 4884282 (1989-11-01), Bridges
patent: 5048047 (1991-09-01), Kozlovsky et al.
patent: 5151917 (1992-09-01), Perilloux et al.
Roullard, III et al., "Transverse Mode Control in High Gain, Millimeter Bore, Waveguide Lasers;" IEEE Journal of Quantum Electronics, vol. QE-13, No. 10, Oct. 1977; pp. 813-818.
Roulnois et al.; "Mode Discrimination and Coupling Losses in Rectangular-Waveguide Resonators with Conventional and Phase-Conjugate Mirrors;" J. Opt. Soc. Am., vol. 72, No. 7, Jul. 1982; pp. 853-860.
Chirikov et al.; "Formation Details of a Waveguide Gas Laser Intensity Distribution;" Infrared Phys., vol. 30, No. 6, 1990, pp. 455-464.

Affiliated with

Also associated with

Rating

Waveguide laser does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Waveguide laser, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Waveguide laser will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1839254