Spectral beam combination of broad-stripe laser diodes

A spectral beam combining (SBC) optical system comprising:

• a broad-stripe laser diode;
• an external resonator cavity comprising:
• a mirror located adjacent to a first facet of said broad-stripe laser diode;
• and
• an output coupler, wherein emissions from a second facet of said broad-stripe laser diode are incident on said output coupler, said output coupler outputting a single output beam;
• a dispersive element interposed between said broad-stripe laser diode and said output coupler, said dispersive element reflecting a portion of said emissions back into said broad-stripe laser diode;
• a collimating optical system interposed between said broad-stripe laser diode and said dispersive element, said collimating optical system spatially overlapping emissions from said broad-stripe laser diode onto said dispersive element;
• a spatial filter interposed between said dispersive element and said output coupler;
• and
• means for creating a plurality of pseudo emitters across said second facet of said broad-stripe laser diode with a corresponding lateral spacing between adjacent pseudo emitters, said means located within said external cavity, wherein said means generates wavelength-periodic variations in transmission or reflectivity, and wherein said lateral spacing is equivalent to at least one half of a fundamental mode diameter associated with said external resonator cavity multiplied by a factor by which the output beam divergence exceeds the diffraction limit.

A method for improving the beam quality of a broad-stripe laser diode, the method comprising the steps of:

• forming a plurality of pseudo emitters from an output of the broad-stripe laser diode;
• laterally spacing said pseudo emitters by at least one half of a fundamental cavity mode diameter multiplied by a factor corresponding to an amount by which an output beam divergence exceeds a system diffraction limit;
• and
• passing a plurality of emissions corresponding to said plurality of pseudo emitters through an SBC optical system.

A method for improving the beam quality of a broad-stripe laser diode, the method comprising the steps of:

• forming a plurality of pseudo emitters from an output of the broad-stripe laser diode;
• passing a plurality of emissions corresponding to said plurality of pseudo emitters through an SBC optical system;
• and
• selecting a slit width for a slit associated with a spatial filter of said SBC optical system so that an image of said slit projected onto a front facet of the broad-strip laser diode is less than twice a lateral spacing of adjacent pseudo emitters multiplied by a factor corresponding to an amount by which an output beam divergence exceeds a system diffraction limit.