Intracavity OPO laser

A laser providing a preselected wavelength comprising:

• a) a laser resonator having a laser resonator cavity formed between a first laser resonator reflective surface and a second laser resonator reflective surface, said laser resonator having a resonator optical axis;
• b) a Nd:YAG, Nd:YLF, Nd:GdVO4 or Nd:YVO4 lasing crystal located within said laser resonator cavity for generating a fundamental wavelength beam;
• c) an optical parametric oscillator (OPO) cavity formed between a first OPO reflective surface and a second OPO reflective surface said optical parametric oscillator cavity having an oscillator optical axis which is in part separate from said resonator optical axis and which in part overlaps said resonator optical axis;
• d) a noncritically phased matched OPO nonlinear crystal for OPO generation located within said OPO cavity along said oscillator optical axis and along said resonator optical axis in optical communication with said first and said second OPO reflective surfaces;
• e) said noncritically phased matched OPO nonlinear crystal oriented to convert said fundamental wavelength beam into a preselected output wavelength beam having a preselected longer wavelength than said fundamental beam;
• f) said optical axes intersecting opposed faces of said OPO nonlinear crystal;
• said opposed faces having a Brewster cut at the intersection of said OPO nonlinear crystal and said axes so that the fundamental beam and the preselected output wavelength beam incident on said crystal within 10 degrees from the Brewster angle for said crystal;
• g) said fundamental beam and said preselected output wavelength beam both incident on said crystal at P-polarization;
• h) said first resonator reflective surface reflective of fundamental wavelength beam and said first OPO reflective surface at least partially reflective of output wavelength beam so that fundamental and output beams reflected by said reflective surfaces propagate back through said OPO nonlinear crystal;
• i) a dichroic mirror located along the overlapping portion of said oscillator optical axis and said resonator optical axis between said OPO nonlinear crystal and said lasing medium;
• said dichroic mirror either highly reflective or highly transmissive for fundamental wavelength beam to direct said fundamental wavelength beam propagating from said lasing medium into said optical parametric oscillator cavity along said oscillator optical axis and through said OPO nonlinear crystal at P-polarization to convert a portion of said fundamental wavelength beam to a P-polarized preselected wavelength beam having a longer wavelength than said fundamental beam;
• said dichroic mirror directing fundamental beam reflected by said first resonator reflective surface back through said lasing medium for amplification and directing preselected output wavelength beam reflected by said first OPO reflective surface for at least partial reflection by said second OPO reflective surface.

A laser for providing a 193 nm beam comprising:

• a) a laser resonator having a laser resonator cavity formed between a first laser resonator reflective surface and a second laser resonator reflective surface, said laser resonator having a resonator optical axis;
• b) a lasing medium located within said laser resonator cavity for generating a fundamental wavelength beam;
• c) said lasing medium being a Nd:YAG or a Nd:YVO4 crystal, producing a 1064 nm fundamental beam or an Nd:YLF crystal producing a 1053 nm;
• d) an optical parametric oscillator (OPO) cavity formed between said first OPO reflective surface and a second OPO reflective surface said optical parametric oscillator cavity having an oscillator optical axis which is in part separate from said resonator optical axis and which in part overlaps said resonator optical axis;
• e) an OPO nonlinear generator for OPO generation located within said OPO cavity along said oscillator optical axis and along said resonator optical axis in optical communication with said first and said third reflective surface;
• said OPO nonlinear generator oriented to convert said 1064 nm or 1053 nm fundamental wavelength beam into an output wavelength beam having a wavelength of about 1544 nm;
• f) means to direct said fundamental wavelength beam into said optical parametric oscillator cavity along said oscillator optical axis and across said OPO nonlinear generator at P-polarization to convert a portion of said fundamental wavelength beam to a 1544 nm output wavelength beam at P-polarization;
• g) said optical axes intersecting opposed faces of said OPO nonlinear crystal;
• said opposed faces having a Brewster cut at the intersection of said OPO nonlinear crystal and said axes so that the fundamental beam and about 1544 output wavelength beam incident on said crystal at P-polarization within 10 degrees from the Brewster angle for said crystal;
• h) said first laser resonator reflective surface reflective of fundamental wavelength beam;
• and said first OPO reflective surface at least partially reflective of output wavelength beam;
• i) means to direct said fundamental and output beams from said first laser resonator reflective surface and from said first OPO reflective surface back through said OPO nonlinear generator to form additional output wavelength beam;
• j) a beam separator to separate said 1544 output wavelength beam from said fundamental wavelength beam;
• k) fundamental beam directing means to direct said separated fundamental beam back through said lasing medium for further amplification;
• l) output beam directing means for directing said separated output wavelength beam to said second OPO reflective surface where said beam is at least partially reflected through said OPO nonlinear crystal;
• m) an output coupler to direct a portion of said 1544 nm output wavelength beam on an output path outside said optical parametric oscillator cavity;
• n) a first, second harmonic generator located along said output path for converting a portion of said 1544 nm beam to 772 nm beam said first second harmonic generator delivering 1544 nm beam and 772 beam on a first second harmonic output path;
• o) a second, second harmonic generator located along said first second harmonic output path, in optical communication with said first second harmonic generator for converting a portion of said 772 nm beam from said first second harmonic generator to 386 nm beam said second, second harmonic generator delivering 772 nm beam and 386 nm beam on a second, second harmonic output path;
• p) a third harmonic generator (1 w+2 w=3 w) located along said second, second harmonic output path, in optical communication with said second, second harmonic generator for converting a portion of said 772 nm beam and a portion of said 386 nm beam to 257 nm beam said third harmonic generator delivering 772 nm beam and 257 nm beam on a third harmonic generator output path;
• a fourth harmonic generator (1 w+3 w=4 w) in optical communication with said third harmonic generator output path for converting a portion of the 772 nm beam and the 257 nm beam to a 193 nm beam;
• said fourth harmonic generator delivering said 193 nm on a fourth harmonic generator output path.

A method of providing a preselected wavelength laser beam comprising:

• a) forming a laser resonator having a laser resonator cavity formed between a first laser cavity reflective surface and a second laser cavity reflective surface, said laser resonator having a resonator optical axis;
• b) exciting a lasing medium located within said laser resonator cavity to generate a fundamental wavelength beam;
• c) forming an optical parametric oscillator (OPO) cavity between a first OPO reflective surface and a second OPO reflective surface, said optical parametric oscillator cavity having an oscillator optical axis which is in part separate from said resonator optical axis and which in part overlaps said resonator optical axis;
• d) pumping an OPO nonlinear generator for OPO generation located within said OPO cavity along said oscillator optical axis and along said resonator optical axis in optical communication with said fundamental beam, said fundamental beam incidenting on said OPO nonlinear generator at P-polarization;
• said OPO nonlinear generator oriented to convert said fundamental wavelength beam into a P-polarized preselected wavelength beam having a preselected longer wavelength than said fundamental beam;
• e) directing said fundamental wavelength beam into said optical parametric oscillator cavity along said oscillator optical axis and through said OPO nonlinear generator to convert a first portion of said fundamental wavelength beam to a preselected wavelength beam having a longer wavelength than said fundamental beam;
• f) said optical axes intersecting opposed faces of said OPO nonlinear generator;
• said opposed faces having a Brewster cut at the intersection of said OPO nonlinear generator and said axes so that the fundamental beam and the preselected wavelength beam incident on said OPO nonlinear generator within 10 degrees from the Brewster angle for said generator;
• g) reflecting said fundamental wavelength beam and at least partially reflecting said preselected wavelength beam back through said OPO nonlinear generator at P-polarization to oscillate said reflected preselected wavelength beam and to convert a second portion of said fundamental laser beam to preselected wavelength beam;
• i) separating said preselected wavelength beam from said fundamental wavelength beam;
• j) directing said separated fundamental beam back through said lasing medium for further amplification;
• k) reflecting at least a portion of said separated preselected wavelength beam through said OPO nonlinear generator.