Laser with reflective etalon tuning element

A tunable laser comprising:

• (a) a laser pump;
• (b) a resonant optical cavity having a round trip light path, said optical cavity having an odd number of reflective surfaces and comprising:
• i) a gain medium responsive to pumping by said laser pump, one face of said gain medium forming a first reflective endface of the resonant optical cavity:
• and ii) a tuning etalon, positioned within the resonant optical cavity, said etalon comprising two spaced apart mirrors having a controllable mirror-to-mirror separation distance, and forming the other reflective endface of said optical cavity so that light traveling on said round trip light path is reflected from the etalon, and whereby the emission wavelength of the gain medium is determined by a selected separation distance of the etalon mirrors and is selected to have a value that differs from a wavelength of peak reflectivity of the etalon.

A laser emitting light at a selected wavelength λ1 said laser comprising a resonant optical cavity having a round trip light path, said cavity having an odd number of reflective surfaces and comprising:

• (a) a laser pump;
• (b) a gain medium, responsive to pumping by said laser pump, the gain medium comprising a single-mode optical waveguide having first and second end faces, wherein the first optical waveguide end face is an output coupler which forms one reflective endface of the resonant optical cavity and wherein the second end face emits a beam including a selected wavelength λ1 and having a selected power Pa;
• (c) a lens that receives the emitted beam and transmits it as a focused beam to;
• (d) a tuning etalon;
• which forms the other reflective endface of the resonant optical cavity, said etalon comprising two spaced apart mirrors;
• having a controllable mirror-to-mirror separation distance, which receives and reflects the focused beam as a distorted and attenuated beam;
• wherein the extent of the beam distortion and beam attenuation depends upon the focused beam wavelength and wherein the reflected beam is received at the second waveguide endface with an optical power Pb and issues from the second endface into the waveguide with an optical power P0, where the ratio P0/Pa has a maximum value at a wavelength λ0 that is determined by a selected separation distance of the etalon mirrors, and wherein the wavelength λ1 differs from a wavelength of peak reflectivity of the etalon and is selected to be approximately equal to λ0.

A method for generating tunable laser light, the method comprising the steps of:

• (a) pumping a laser gain medium, positioned within a resonant optical cavity having a round trip light path and having an odd number of reflective surfaces and wherein one face of said gain medium forms the first reflective endface of said resonant optical cavity;
• (b) positioning in the round trip light path a tuning etalon which forms the second reflective endface of said resonant optical cavity and wherein said etalon comprises two spaced apart mirrors having a controllable mirror-to-mirror separation distance;
• (c) receiving and reflecting light traveling in the round trip light path at the etalon,
• whereby an emission wavelength of the laser is determined by a selected separation distance for the etalon mirrors.

A method for generating tunable laser light, the method comprising:

• (a) using a laser pump to pump a laser gain medium positioned within a resonant optical cavity having a round trip light path and having an odd number of reflective surfaces and wherein one face of said gain medium forms the first reflective end face of said resonant optical cavity;
• (b) positioning in the round trip light path a tuning etalon, which forms the second reflective endface of said resonant optical cavity and wherein said etalon comprises two spaced apart mirrors having a controllable mirror-to-mirror separation distance,
• (c) receiving and reflecting light traveling in the round trip list path at the etalon,
• whereby the emission wavelength of the laser is determined by a selected separation distance for the etalon mirrors and has a value that differs from a wavelength of peak reflectivity of the etalon.

A method for generating tunable laser lights of a wavelength λ1 comprising the steps of:

• (a) pumping a gain medium, positioned within a resonant optical cavity having a round trip light path and an odd number of reflective surfaces, said gain medium comprising a single-mode optical waveguide having first and second endfaces, wherein the first endface is the first reflective end face of said resonant optical cavity and serves as an output coupler for the resonant optical cavity and wherein the second endface emits a beam including a selected wavelength λ1 and having a selected power Pa;
• (b) passing said emitted beam through a lens to provide a focused beam;
• and
• (c) receiving and reflecting said focused beam from a tuning etalon, which forms the second reflective endface of the resonant optical cavity, said etalon comprising two spaced apart mirrors having a controllable mirror-to-mirror separation distance, to generate a distorted and attenuated version of the focused beam, where the extent of the distortion and attenuation depends upon the wavelength λ1,
• where the reflected beam is received at the second endface with an optical power Pb and issues from the second endface into the waveguide with an optical power P0, where the ratio P0/Pa has a maximum value at a wavelength λ0 which is determined by a selected separation distance of the etalon mirrors, and wherein the wavelength λ1 differs from a wavelength of peak reflectivity of the etalon and is selected to be approximately equal to λ0.