Optical amplifier with folded light path and laser-amplifier combination

An optical amplifier device comprising,

• a body of optical gain material having opposed front and rear facets, said front facet having a low reflectivity, said rear facet having a high reflectivity, said body having at least a first amplifier region defined therein between said front and rear facets, said first amplifier region accepting a light input through one of said facets, said light propagating in said first amplifier region of said body along a light path incident on said rear facet at an angle other than normal to said rear facet, and
• means for pumping said body of optical gain material to cause amplification of said light propagating in said light path, at least a portion of said amplified light being emitted from said front facet of said body.

A master oscillator power amplifier device comprising,

• a semiconductor laser diode providing a coherent light beam,
• at least one amplifier region formed of a semiconductor heterostructure providing optical gain for said light beam, said amplifier having a high reflectivity rear facet and a low reflectivity front facet, said amplifier having at least a first amplifier region accepting said light beam, said coherent light beam propagating in said first amplifier region of said amplifier along a light path that is folded into a V-shape by reflection of said light beam at said rear facet, and
• means for pumping said amplifier to cause amplification of said coherent light beam as it propagates in said light path, at least a portion of said amplified light beam being emitted from said front facet cf said amplifier.

An integrated master oscillator power amplifier device comprising,

• a substrate,
• a semiconductor laser diode formed on said substrate having an electrically pumped active gain region and grating means for providing feedback of light generated in said active gain region, said laser providing a laser light beam output from said gain region,
• an amplifier formed on said substrate having a zig-zag shaped waveguide connected to said laser to receive said laser light and disposed between a front partially reflective facet of said substrate and means formed on said substrate at a back side of said zig-zag shaped waveguide for providing high reflectivity, said waveguide being electrically pumpable to provide amplification of said laser light.

An optical amplifier device comprising

• a body of optical gain material having a low reflectivity front facet with an input region and an output region, the body also having an amplifier region defined therein accepting light input through the front facet at the input region thereof,
• means within said body for providing a nonlinear light path passing through the amplifier region, said light path providing means including a pair of waveguides, a first one of said waveguides extending from said input region of the front facet to a rear end of said body and supporting only a single transverse mode of light propagation, a second one of said waveguides extending from said rear end of said body proximate to said first waveguide to said output region of the front facet, said second waveguide having a greater width than said first waveguide, said light path providing means also including means at said rear end of said body proximate to said pair of waveguides for coupling light propagating in said first waveguide into said second waveguide, and
• means for electrically pumping said body to cause amplification of light in said light path, said amplified light being emitted from said second waveguide at said output region of said front facet.