Patent ID: 8849080

Claim:
An optical fiber coupler comprising: an optical fiber core having an index of refraction n 1 ; a cladding adjacent to and surrounding said core, said cladding having an index of refraction n 2 , wherein n 1 is greater than n 2 , said core and cladding extending from a terminal end to an output end wherein said cladding has a window channel formed in said cladding having a depth substantially equal to a thickness of said cladding; a reflective portion provided at the terminal end for reflecting light towards the output end; a coupling window, integrally formed within a first side of the cladding, configured to provide a direct coupling path for light injected into said coupling window to enter said core, said coupling window extending substantially entirely through said cladding in abutting relation to said core, said coupling window comprising an optical material having an index of refraction n 3 wherein n 3 is greater than n 1 wherein said coupling window optical material comprises a photon trap structure positioned at said coupling window for preventing reflection of light directly from said laser source back to said laser source; a laser source joined to emit a laser light beam into said coupling window, passing directly through said coupling window and directly coupled into said core; an output coupler provided in the output end of said core for reflecting a portion of light toward said terminal end and transmitting another portion of light as output; a Bragg grating formed in the core having a pitch and being positioned to reflect light from said laser source toward said output coupler, and further positioned to reflect light from said output coupler toward said laser source, said Bragg grating pitch being variable in response to a change in temperature; and a thermal control device provided proximate said core having said Bragg grating, said thermal control device being capable of adjusting the temperature of said core to a preselected temperature thereby adjusting the Bragg grating pitch.