Single frequency high power semiconductor laser

A heterostructure semiconductor laser comprising:

• an elongated active gain medium layer;
• a relatively narrower rear facet at one end of the gain layer;
• a relatively wider output facet at the other end of the layer;
• means for pumping the gain medium for stimulated emission of radiation in an area having parallel edges adjacent to the rear facet and having edges diverging from the ends of the parallel edges toward the output facet;
• and
• means between the facets for selecting a single longitudinal oscillation mode independent of Fabry-Perot oscillation modes.

A heterostructure semiconductor laser comprising:

• an elongated active gain medium layer;
• a relatively narrower rear facet at one end of the layer;
• a relatively wider output facet at the other end of the layer;
• means for pumping the gain layer for stimulated emission of radiation in an area having edges diverging from the vicinity of the rear facet toward the output facet;
• and
• a distributed feedback grating in a pumped area of the gain layer for selecting a single longitudinal oscillation mode.

A heterostructure semiconductor laser comprising:

• an active gain medium layer;
• means for making electrical contact with one face of the gain layer;
• means for making electrical contact with the opposite face of the gain layer only in an area having a first region with edges diverging from a narrower end toward a wider end and a second region having parallel edges extending from the narrower end of the diverging region for passing current through the so-defined area of the gain layer;
• and
• means for selecting a single longitudinal oscillation mode of radiation in the area of the gain layer through which current passes.

A distributed feedback heterostructure semiconductor laser comprising:

• an active gain medium layer;
• means for pumping an elongated symmetrical trapezoidal area of the gain layer for stimulating radiation therein;
• a distributed feedback grating in the trapezoidal area for selecting a single longitudinal oscillation mode of radiation in the pumped area of the gain layer;
• and
• a non-pumped area of the gain layer lying along each non-parallel edge of the trapezoidal area.

A heterostructure semiconductor laser comprising:

• an elongated active gain medium layer;
• a relatively narrower rear facet at one end of the gain layer;
• a relatively wider output facet at the other end of the layer;
• means for pumping the gain medium for stimulated emission of radiation in an area having parallel edges adjacent to the rear facet and having edges diverging from the ends of the parallel edges toward the output facet;
• and
• a diffraction grating forming at least one facet of the laser for selecting a single longitudinal oscillation mode.