Analog external cavity laser

Abstract

The present invention relates to the analog external cavity lasers (ECLs) including designs, materials, methods of manufacturing and methods of use for such ECLs and packages for such ECLs. Numerous criteria are presented that lead to improved cost/performance for ECLs and for systems incorporating such ECLs.

1 - 18 . (canceled) 
     
     
         19 . An optical transmitter comprising:
 an external cavity laser for generating an optical signal and transmitting the optical signal over a dispersive fiber optic link;   a first piezoelectric transducer coupled to the external cavity laser;   an electronic circuit coupled to the piezoelectric transducer to change spectral characteristics of the external cavity laser through changing physical properties of the external cavity laser by applying a time varying stress to the external cavity laser, thereby reducing an effect of noise in a received signal arising from stimulated Brillouin scattering (SBS) generated in the dispersive fiber optic link.   
     
     
         20 . The optical transmitter of  claim 19  arranged so that the optical signal is launched at 1550 nm. 
     
     
         21 . The optical transmitter of  claim 19  wherein the external cavity laser comprises a semiconductor laser coupled to a fiber Bragg grating (FBG), the optical transmitter arranged so that the time varying stress is applied to the FBG. 
     
     
         22 . The optical transmitter of  claim 19  wherein the external cavity laser comprises:
 a) a light source having a reflective back facet and a transmissive front facet, said light source further comprising a Fabry-Perot gain element with an active length between approximately 300 micrometers and approximately 600 micrometers, wherein said light source has a symmetrical far-field beam profile; and   b) a partially reflective feedback element forming a laser cavity in cooperation with said reflective back facet.   
     
     
         23 . The optical transmitter of  claim 22  wherein the ratio of mode spacing to the bandwidth of the feedback element is from approximately 0.5 to approximately 1.3. 
     
     
         24 . The optical transmitter of  claim 19  wherein the first piezoelectric transducer is attached to the external cavity laser. 
     
     
         25 . The optical transmitter of  claim 19  wherein at least a portion of the external cavity laser is mounted to a substrate and the first piezoelectric transducer is attached to the substrate. 
     
     
         26 . The optical transmitter of  claim 19  comprising a second piezoelectric transducer, wherein the first piezoelectric transducer is attached to a first side of the external cavity laser and the second piezoelectric transducer is attached to a second side of the external cavity laser, wherein the first side and second side are substantially opposite to each other. 
     
     
         27 . The optical transmitter of  claim 19  wherein the piezoelectric transducer comprises a piezoelectric coating disposed on the external cavity laser. 
     
     
         28 . In an optical system having an optical transmission source comprising a light source optically coupled with an in-line grating to form a laser, a method of lessening effects of noise in a received signal arising from stimulated Brillouin scattering (SBS) generated in a dispersive fiber optic link optically coupled with the laser, the method comprising:
 applying a time varying stress to the in-line grating with a first piezoelectric transducer so as to change spectral characteristics of the in-line grating.   
     
     
         29 . The method of  claim 28  wherein the time varying stress applied to the in-line grating is a periodic stress. 
     
     
         30 . The method of  claim 28  wherein the spectral characteristics include a refractive index of the grating. 
     
     
         31 . The method of  claim 28  wherein the in-line grating is a fiber Bragg grating (FBG). 
     
     
         32 . The method of  claim 28  wherein the laser is a narrow band laser. 
     
     
         33 . The method of  claim 28 , wherein the time varying stress is applied to the grating at a rate that is sufficient to substantially lessen the effects of the SBS. 
     
     
         34 . The method of  claim 28  wherein the first piezoelectric transducer is attached to the in-line grating. 
     
     
         35 . The method of  claim 28  wherein the optical system comprises a second piezoelectric transducer, wherein the first piezoelectric transducer is attached to a first side of the in-line grating and the second piezoelectric transducer is attached to a second side of the in-line grating, wherein the first side and second side are substantially opposite to each other. 
     
     
         36 . A system comprising:
 a dispersive fiber optic link;   a laser optically coupled with the dispersive fiber optic link, wherein the laser includes a narrow band optical source and a fiber Bragg grating (FBG) forming an output facet of the laser; and   first piezoelectric means for dithering the spectral response of the FBG by applying a time varying stress to the FBG to reduce noise in a received signal arising from stimulated Brillouin scattering (SBS) generated in the dispersive optical fiber link.   
     
     
         37 . The system of  claim 36  wherein the narrow band optical source has a symmetrical far-field beam profile. 
     
     
         38 . The system of  claim 36  wherein the first piezoelectric means is attached to the FBG. 
     
     
         39 . The system of  claim 36  wherein the FBG is mounted to a substrate and the piezoelectric means is attached to the substrate. 
     
     
         40 . The system of  claim 36  comprising a second piezoelectric means, wherein the first piezoelectric means is attached to a first side of the FBG and the second piezoelectric means is attached to a second side of the FBG, wherein the first side and second side are substantially opposite to each other. 
     
     
         41 . The system of  claim 36  wherein the piezoelectric means comprises a piezoelectric coating disposed on the FBG. 
     
     
         42 . The system of  claim 36  wherein the laser comprises a feedback element and the ratio of mode spacing to the bandwidth of the feedback element is from approximately 0.5 to approximately 1.3.