Method and system for hybrid integration of a tunable laser

Abstract

A cable television transmitter includes a substrate including a silicon material, control electronics disposed in the substrate, and a gain medium coupled to the substrate. The gain medium includes a compound semiconductor material. The cable television transmitter also includes an optical modulator optically coupled to the gain medium and electrically coupled to the control electronics, a waveguide disposed in the substrate and optically coupled to the gain medium, a first wavelength selective element characterized by a first reflectance spectrum and disposed in the substrate, and a second wavelength selective element characterized by a second reflectance spectrum and disposed in the substrate. The cable television transmitter further includes an optical coupler disposed in the substrate and joining the first wavelength selective element, the second wavelength selective element, and the waveguide and an output mirror.

1 . (canceled) 
     
     
         2 . A tunable laser comprising:
 a gain medium comprising a compound semiconductor material; and   a substrate comprising a silicon material, defining a waveguide, and supporting the gain medium;   a first tunable wavelength selective element disposed in the substrate and characterized by a first reflectance spectrum having a first plurality of reflectance peaks separated by a first spacing interval; and   a second tunable wavelength selective element disposed in the substrate and characterized by a second reflectance spectrum having a second plurality of reflectance peaks separated by a second spacing interval that is different from the first spacing interval.   
     
     
         3 . The tunable laser of  claim 2 , wherein a surface of the compound semiconductor material forms an output mirror, and wherein the first and second tunable wavelength selective elements are optically coupled with the gain medium through the waveguide, such that the first and second reflectance spectra constructively interfere at a single one of each of the first and second plurality of reflectance peaks to select a single cavity mode, and the tunable laser emits the single cavity mode through the output mirror. 
     
     
         4 . The tunable laser of  claim 2 , further comprising an optical coupler disposed in the substrate and coupling the first and second tunable wavelength selective elements with the waveguide. 
     
     
         5 . The tunable laser of  claim 4 , wherein the optical coupler is a multimode interference coupler. 
     
     
         6 . The tunable laser of  claim 2  wherein at least one of the first and second tunable wavelength selective elements comprises an index of refraction adjustment device. 
     
     
         7 . The tunable laser of  claim 6  wherein the index of refraction adjustment device comprises a heater. 
     
     
         8 . The tunable laser of  claim 7  wherein the at least one of the first and second tunable wavelength selective elements further comprises a temperature sensor. 
     
     
         9 . The tunable laser of  claim 2  wherein the silicon material comprises a silicon on insulator wafer. 
     
     
         10 . The tunable laser of  claim 9  wherein the silicon on insulator wafer comprises a silicon substrate, an insulating layer disposed on the silicon substrate, and a silicon layer disposed on the insulating layer, wherein the first and second tunable wavelength selective elements are disposed in the silicon layer. 
     
     
         11 . The tunable laser of  claim 2  wherein the gain medium and the silicon material form a semiconductor/metal/semiconductor bond. 
     
     
         12 . The tunable laser of  claim 2  further comprising a phase adjustment section disposed in the silicon material between the waveguide and the first and second tunable wavelength selective elements. 
     
     
         13 . The tunable laser of  claim 12 , wherein the phase adjustment section comprises a heater. 
     
     
         14 . A method of operating a tunable laser, the method comprising:
 tuning a first modulated grating reflector, wherein the first modulated grating reflector is characterized by a first reflectance spectrum including a first plurality of reflectance peaks;   tuning a second modulated grating reflector, wherein the second modulated grating reflector is characterized by a second reflectance spectrum including a second plurality of reflectance peaks;   generating optical emission from a gain medium comprising a compound semiconductor material;   reflecting a portion of the optical emission from the first modulated grating reflector and the second modulated grating reflector, the reflected portion of the optical emission having a spectral peak defined by an overlap of one of the first plurality of reflectance peaks and one of the second plurality of reflectance peaks;   amplifying the reflected portion of the optical emission in the gain medium; and   transmitting a portion of the amplified optical emission through an output mirror.   
     
     
         15 . The tunable laser of  claim 14 , wherein tuning the first and second modulated grating reflectors comprises modifying a refractive index within the first and second modulated grating reflectors. 
     
     
         16 . The tunable laser of  claim 15 , wherein modifying the refractive index comprises using a heater to change a temperature of a region surrounding the modulated grating reflectors. 
     
     
         17 . The tunable laser of  claim 14 , further comprising using a silicon waveguide to transmit the optical emission from the gain medium to the first and second modulated grating reflectors. 
     
     
         18 . The tunable laser of  claim 14 , further comprising adjusting a phase of the optical emission from the gain medium, by using a phase adjustment section integrated with a silicon layer. 
     
     
         19 . The tunable laser of  claim 18 , wherein using the phase adjustment section comprises using a heater to adjust an index of refraction of the silicon layer. 
     
     
         20 . The tunable laser of  claim 14 , further comprising optically modulating the transmitted portion of the amplified optical emission to form a pulsed optical output. 
     
     
         21 . The tunable laser of  claim 14 , further comprising phase modulating the pulsed optical output.