Laser with narrow bandwidth antireflection filter for frequency selection

A frequency-converted laser comprising:

• a laser cavity including a first and a second end mirror;
• a gain medium situated within said laser cavity, said gain medium defining a gain-bandwidth;
• a pump source arranged to pump said gain medium to thereby excite laser emission within said laser cavity;
• a nonlinear element situated within said laser cavity, said nonlinear element arranged for frequency conversion of said laser emission within a required spectral range for efficient frequency conversion;
• an AR coating formed on a transmissive surface within said laser cavity, said AR coating defining a minimum loss point within said gain-bandwidth of said gain medium;
• wherein said AR coating constrains the bandwidth of said laser emission within said required spectral range for frequency conversion;
• and
• an etalon situated within said laser cavity, wherein said etalon has an FSR greater than said required spectral range, so that said etalon has at most one transmission peak within said spectral range, and said etalon and said AR coating operate cooperatively to constrain the bandwidth of said laser emission within said required spectral range for frequency conversion.