Channel-switched tunable laser for DWDM communications

A tunable laser source comprising:

• a laser gain medium,
• an intracavity waveguide segment optically coupled to said gain medium, and
• electro-optic feedback means for defining a resonant laser cavity including said gain medium and intracavity waveguide segment, said electro-optic feedback means including electrode means for tuning a frequency of operation of said laser cavity,
• wherein said gain medium is characterized by a positive refractive index change with increase in temperature and said intracavity waveguide segment is characterized by a negative refractive index change with increases in temperature, said gain medium and intracavity waveguide segments having optical path lengths chosen such that a round trip optical path in said resonant cavity has an optical length that is substantially independent of ambient temperature over a specified ambient temperature range.

An athermal laser source comprising:

• a laser gain medium,
• an intracavity waveguide segment optically coupled to said gain medium, and
• frequency selective feedback means having a feedback bandwidth and defining a resonant laser cavity including said gain medium and intracavity waveguide segment, said feedback bandwidth being sufficiently narrow compared to the free spectral range of said cavity so that only one of the longitudinal modes of said cavity is substantially excited by said gain medium,
• wherein said gain medium is characterized by a positive refractive index change with increase in temperature and said intracavity waveguide segment is characterized by a negative refractive index change with increases in temperature, said gain medium and intracavity waveguide segments having optical path lengths chosen such that a round trip optical path in said resonant cavity has an optical length that is substantially independent of ambient temperature over a specified ambient temperature range.

A ring laser apparatus comprising:

• a laser gain medium,
• first and second waveguide segments optically coupled to said laser gain medium;
• and
• a frequency selective means for coupling optical energy between said first and second waveguide segments and also coupling a portion of said optical energy out of at least one of said waveguide segments to form an optical output,
• wherein said laser gain medium and said optically coupled first and second waveguide segments form a ring resonator having a round trip optical path characterized by a round trip optical length, at least one of said waveguide segments characterized by a negative refractive index change with increases in temperature and having a length chosen such that the round trip optical length is athermal.

An athermal ring laser source comprising:

• a laser gain medium,
• an first intracavity waveguide segment optically coupled to said gain medium,
• an second intracavity waveguide segment optically coupled to said gain medium, and
• frequency selective feedback means disposed to couple optical energy between said first and second waveguide segments having a feedback bandwidth and defining a resonant ring cavity including said gain medium and said first and second intracavity waveguide segments,
• wherein said gain medium is characterized by a positive refractive index change with increase in temperature and said first intracavity waveguide segment is characterized by a negative refractive index change with increases in temperature, said gain medium and first intracavity waveguide segments having optical path lengths chosen such that a round trip optical path in said resonant ring cavity has an optical length that is substantially independent of ambient temperature over a specified ambient temperature range.