Small packaged tunable laser

Abstract

A tunable laser configured in a small package subassembly including a gain chip positioned in the interior space between first and second tunable filter subassemblies. The tunable laser is packaged in either a rectangular or cylindrical housing, with an electrical input interface positioned at one end of the housing.

1 . A small, packaged tunable laser comprising:
 a housing having a volume of less than 0.6 cubic centimeters, forming a hermetically sealed interior space that includes a major first axis;   an electrical input interface positioned on the exterior of the housing and configured to receive an information—containing electrical signal;   an optical output interface positioned on the exterior of the housing, the optical output interface configured to transmit a continuous wave optical beam;   a tunable semiconductor laser positioned in the interior space and operable to emit a laser beam along a second axis and having a selectable wavelength;   a beam splitter positioned in the interior space in the path of the laser beam for producing a first beam substantially orthogonal to the second axis and along the major first axis directed to the optical output interface, and a second beam; and   a photodiode disposed in the path of the second beam for determining the emitted intensity of the laser beam.   
     
     
         2 . The tunable laser of  claim 1 , wherein the photodiode is positioned on the base and below the beam splitter. 
     
     
         3 . The tunable laser of  claim 1 , wherein the photodiode is positioned in the path of the laser beam downstream from the beam splitter. 
     
     
         4 . The tunable laser of  claim 1 , wherein the tunable semiconductor laser is an external cavity laser that includes a gain chip disposed between first and second tunable optical filter subassemblies. 
     
     
         5 . The tunable laser of  claim 4 , wherein the first and second tunable filter subassemblies comprise a Vernier tuning mechanism including respective first and second optical filters having respective sets of transmission peaks having slightly different free spectral ranges and similar finesses, and wherein tuning is performed by shifting the set of transmission peaks of the second optical filter relative to the set of transmission peaks of the first optical filter to align a single transmission peak of each of the first and second sets of transmission peaks. 
     
     
         6 . The tunable laser of  claim 4 , wherein the first tunable filter comprises a facet defining the rear facet of the external cavity laser. 
     
     
         7 . The tunable laser of  claim 1 , wherein the second tunable filter comprise. 
     
     
         8 . The tunable laser of  claim 1 , further comprising coupling optics positioned in the interior space along the optical path between the beam splitter and the optical output interface, the coupling optics including a pair of coupling lenses and an isolator. 
     
     
         9 . The tunable laser of  claim 1 , further comprising a focusing lens assembly positioned in the interior space along an optical path of the first beam emitted by the beam splitter to operatively couple the first beam to the optical output interface. 
     
     
         10 . A small, packaged tunable optical laser comprising:
 a housing having a volume of less than 0.6 cubic centimeters, with opposing first and second ends, and exterior walls forming a hermetically sealed interior space that includes a major first axis that extends through the first and second ends;   an electrical input interface positioned on a first end of the exterior of the housing and configured to receive an information-containing electrical signal;   an optical output interface positioned at the second end of the housing and aligned with the major axis, the optical output interface configured to transmit an optical communication beam;   a gain chip positioned in the interior space between first and second tunable filters and operable to emit a laser beam; and   a composite optical assembly positioned in the interior space along an optical path of the laser beam to operatively couple the laser beam to the optical output interface.   
     
     
         11 . The tunable laser of  claim 10 , wherein the electrical input interface includes a plurality of pins that extends outward from the first end of the housing. 
     
     
         12 . The tunable laser of  claim 10 , wherein the housing is a cylinder and the optical path is aligned along the center major axis of the cylinder. 
     
     
         13 . The tunable laser of  claim 10 , wherein the second tunable filter includes an end facet tilted with respect to the optical axis to prevent the incoming light from the laser from reflecting back into the cavity of the laser. 
     
     
         14 . The tunable laser of  claim 10 , wherein the tunable filters further comprises a Bernier tuning mechanism including respective first and second optical filters having respective sets of transmissions peaks having slightly different free spectral ranges and similar finesses, and wherein tuning is performed by shifting the set of transmission peaks of the second optical filter relative to the set of transmissions peaks of the first optical filter to align a single transmission peak of each of the first and second sets of transmission peaks, wherein the cavity length actuator is disposed between the first and second optical filters of the Bernier tuning mechanism, and further wherein the cavity length actuator comprises an anti-reflection coating on its planar surface. 
     
     
         15 . The tunable laser of  claim 10 , wherein the optical output interface is an aperture in the cylindrical end face, and a ferrule connected to an optical fiber pigtail. 
     
     
         16 . The tunable laser of  claim 10 , wherein the optical output interface includes coupling optics positioned in the interior space along the optical path between the composite optical assembly and a focusing lens assembly, the coupling optics including a coupling lens and an isolator. 
     
     
         17 . The tunable laser of  claim 10 , further comprising a photodiode disposed adjacent to the composite optical assembly. 
     
     
         18 . The tunable laser of  claim 1 , wherein composite optical assembly including the beam splitter is arranged on the wedge-shaped support so that a plane of the beam splitter is at a 45 degree angle with respect to the beam. 
     
     
         19 . A small, packaged tunable laser comprising:
 a housing, the exterior walls forming a hermetically sealed interior space;   an electrical input interface positioned on the exterior of the housing and configured to receive an information—containing electrical signal; and   an optical output interface positioned on the exterior of the housing, the optical output interface configured to transmit a continuous wave optical beam;   a tunable laser subassembly including laser gain element positioned in the interior space, a first optical filter disposed on one side of the laser gain element; and a second optical filter disposed on the other side of the laser gain element; the subassembly operable to emit a laser beam having a selectable wavelength.   
     
     
         20 . The tunable laser of  claim 19 , further comprising:
 a beam splitter positioned in the interior space of the housing and in the path of the laser beam for producing a first beam, directed to the optical output interface, and a second beam; and   a photodiode disposed in the path of the second beam for determining the emitted intensity of the laser beam.