Resonator mirror for an optical resonator of a laser apparatus, and laser apparatus

Abstract

The invention relates to a resonator mirror (4) for an optical resonator (1) of a laser device (2), especially of a gas laser or a slab waveguide laser, comprising a reflective surface (6) with a structured area (5) which spans across a region of the reflective surface (6) centered about the optical axis (5). According to one variant of the principle underlying the invention, the structured area (5) has at least one reflective surface cross-section (8, 18, 28, 38, 48, 58, 68) which is offset with respect to the reflective surface (6) outside the structured area (5) and parallel to the optical axis (A) by half of a predefined wavelength or by a whole multiple of half the predefined wavelength. According to another variant, the structured area (5) has at least two surface cross-sections (8, 18, 28, 38, 48, 58, 68) which are offset against each other and parallel to the optical axis (A) by half of a predefined wavelength or by a whole multiple of half the predefined wavelength. In addition, the invention relates to a laser device (2) whose optical resonator (1) comprises a resonator mirror (4) designed in such a manner.

1 - 16 . (canceled) 
     
     
         17 . A laser device, comprising:
 an optically-active medium having a plurality of frequency bands;   first and second resonator mirrors, the resonator mirrors arranged around the optically-active medium to form an unstable optical resonator, the unstable optical resonator having an optical axis;   wherein the second resonator mirror includes a structured area, the structured area occupying less than 30% of the second resonator mirror, the structured area located on the optical axis, the structured area having at least one reflective surface that is offset against a reflective surface of the second resonator mirror outside the structured area, the offset being along the optical axis and equal to half or multiples-of-half of a selected wavelength in a desired frequency band;   wherein the structured area introduces reflection losses for frequency bands to be suppressed, the desired frequency band thereby having higher net amplification than the suppressed frequency bands during operation of the laser device; and   wherein the first resonator mirror and the structured area form a stable optical resonator near the optical axis, the stable optical resonator seeding the unstable optical resonator during operation of the laser device.   
     
     
         18 . The laser device of  claim 17 , wherein the optically-active medium is a gas mixture that contains carbon dioxide. 
     
     
         19 . The laser device of  claim 17 , wherein the optically-active medium is a gas mixture that contains carbon monoxide. 
     
     
         20 . The laser device of  claim 17 , wherein the at-least-one reflective surface of the structured area is raised with respect to the reflective surface of the second resonator mirror outside the structured area. 
     
     
         21 . The laser device of  claim 17 , wherein the at-least-one reflective surface of the structured area is recessed with respect to the reflective surface of the second resonator mirror outside the structured area. 
     
     
         22 . The laser device of  claim 17 , wherein the structured area occupies less than 15% of the second resonator mirror. 
     
     
         23 . The laser device of  claim 22 , wherein the structured area occupies less than 5% of the second resonator mirror. 
     
     
         24 . The laser device of  claim 17 , wherein the at-least-one reflective surface of the structured area is flat. 
     
     
         25 . The laser device of  claim 17 , wherein the at-least-one reflective surface of the structured area has curvature. 
     
     
         26 . The laser device of  claim 25 , wherein the curvature of the at-least-one reflective surface of the structured area corresponds to a curvature of the reflective surface of the second resonator mirror outside the structured area. 
     
     
         27 . The laser device of  claim 17 , wherein the structured area has a plurality of stepped reflective surfaces, respectively offset against each other by half or multiples-of-half of the selected wavelength. 
     
     
         28 . The laser device of  claim 27 , wherein the stepped reflective surfaces are circular in shape. 
     
     
         29 . The laser device of  claim 28 , wherein the stepped reflective surfaces are concentrically arranged with respect to each other. 
     
     
         30 . The laser device of  claim 27 , wherein the stepped reflective surfaces are rectangular in shape. 
     
     
         31 . The laser device of  claim 17 , wherein the structured area has one stepped reflective surface laterally spanning the second resonator mirror. 
     
     
         32 . The laser device of  claim 17 , wherein the structured area is limited to an area about the optical axis having a diameter of a few millimeters. 
     
     
         33 . The laser device of  claim 17 , wherein the structured area is limited to an area about the optical axis having a diameter of less than one millimeter. 
     
     
         34 . The laser device of  claim 17 , wherein the unstable laser-resonator is a negative-branch unstable resonator. 
     
     
         35 . The laser device of  claim 17 , wherein the first resonator mirror includes another structured area. 
     
     
         36 . The laser device of  claim 35 , wherein the structured areas of the first and second resonator mirrors are complementary, one structured area being raised with respect to the reflective surface outside thereof, the other structured area being recessed with respect to the respective reflective surface outside thereof.