Tunable external cavity laser

A tuning apparatus for a light beam, comprising

• (a) a first tunable wavelength selection element positioned in said light beam, said first tunable element configured to define a first plurality of transmission peaks;
• (b) a second tunable wavelength selection element positioned in said light beam, said second tunable element configured to define a second plurality of transmission peaks;
• (c) said first and second pluralities of transmission peaks defining a single joint transmission peak within a selected wavelength range;
• and
• (d) said first and second tunable wavelength selection elements operable to adjust said joint transmission peak according to adjustment of said first and second tunable elements.

A laser apparatus, comprising:

• (a) a gain medium emitting a light beam;
• (b) a first tunable wavelength selection element positioned in said light beam and having a first adjustable free spectral range;
• (c) a second tunable wavelength selection element positioned in said light beam and having a second adjustable free spectral range;
• and
• (d) said first and second tunable wavelength selection elements defining a joint free spectral range with a single joint transmission peak within a selected wavelength range, said single joint transmission peak adjustable in phase according to tuning of said first and second tunable wavelength selection elements.

A method for tuning a light beam, comprising:

• (a) positioning a first tunable wavelength selection element in said light beam, said first tunable wavelength selection element having a first adjustable free spectral range;
• (b) positioning a second tunable wavelength selection element in said light beam, said second tunable element having a second adjustable free spectral range;
• (c) defining a joint free spectral range from said first and second free spectral ranges;
• and
• (d) adjusting said joint free spectral range by tuning said first and second tunable wavelength selection elements.

A method for laser operation, comprising:

• (a) emitting a light beam from a first facet of a gain medium:
• (b) positioning an end reflector in said light beam, said end reflector and a second facet of said gain medium defining an external laser cavity;
• (c) positioning first and second tunable wavelength selection elements in said light beam before said end reflector, said first and second tunable wavelength selection elements respectively configured to define first and second pluralities of transmission peaks;
• (d) defining a single joint transmission peak from said first and second pluralities of transmission peaks;
• and
• (e) adjusting said joint transmission peak by tuning said first and second tunable wavelength selection elements.