Improved self-mix module utilizing filters

Abstract

A system and method for generating, enhancing, and detecting the amplitude and phase modulation of a laser under a condition of self-mixing is provided. The system may comprise a laser and a detector to extract the characteristic self-mix signal, which is then interpreted using algorithms implemented in hardware or software. In the case of the laser being a Vertical Cavity Surface Emitting laser (VCSEL), the output signal can be detected by monitoring the surface light emission by means of a beam splitter, or in some embodiments as emission from the bottom surface of the laser. In some embodiments, the system may further comprise a wavelength filter such as an etalon in the signal path.

1 . A sensor device for laser light emission comprising:
 at least one laser emitting a light from at least one aperture, the laser comprising a cavity and at least one mirror;   a detector;   a filter in a fixed position relative to the cavity; and   at least one optical lens that approximately focuses a portion of the laser emission onto a target surface and couples a portion of any light reflected from the target surface back into the laser cavity,   wherein a first optical path carries a first portion of the light emitted from the laser between the laser and the target surface and a second optical path carries a second portion of the light emitted from the laser between the laser and the detector,   wherein the target surface is disposed only within the first optical path; and   wherein the filter is disposed within at least the second optical path.   
     
     
         2 . The sensor device of  claim 1 , wherein the filter is disposed within the first optical path and the second optical path. 
     
     
         3 . The sensor device of  claim 1 , wherein the laser is a VCSEL. 
     
     
         4 . The sensor device of  claim 3 , wherein the detector is grown on the same substrate as the laser. 
     
     
         5 . The sensor device  claim 1 , wherein the filter is one of a grating or an etalon. 
     
     
         6 . The sensor device of  claim 1 , wherein the laser has multiple apertures for emitting light. 
     
     
         7 . The sensor device of  claim 1 , further comprising a means of sampling a portion of the laser light emission and presenting it to the detector. 
     
     
         8 . The sensor device of  claim 7 , wherein the means of sampling is a beam splitter. 
     
     
         9 . The sensor device of  claim 8 , wherein the beam splitter is positioned at an angle relative to an optical axis of the laser. 
     
     
         10 - 35 . (canceled) 
     
     
         36 . A packaged sensor device comprising:
 a housing;   a laser emitting a light from an aperture, the light having a wavelength;   a detector mounted to a substrate at a first end of the housing;   a filter disposed between the laser and the detector; and   at least one optical lens at a second end of the housing.   
     
     
         37 . The packaged sensor device of  claim 36 , wherein the laser is a VCSEL. 
     
     
         38 - 44 . (canceled) 
     
     
         45 . The packaged sensor device of  claim 36 , wherein the filter is an etalon. 
     
     
         46 . The packaged sensor device of  claim 36 , wherein the detector is selected from the group consisting of: a photodetector, PIN photodetector, a resonant cavity photodetector, or an avalanche photodiode. 
     
     
         47 - 53 . (canceled) 
     
     
         54 . The packaged sensor device of  claim 36 , wherein the laser is a VCSEL having at least one mirror and a substrate, and the filter is an etalon comprising at least one mirror of the VCSEL and the substrate. 
     
     
         55 - 62 . (canceled) 
     
     
         63 . The packaged sensor device of  claim 36 , wherein the filter has two faces in parallel, wherein each face has a mirror that is highly reflective at the wavelength. 
     
     
         64 . (canceled) 
     
     
         65 . The packaged sensor device of  claim 36 , wherein the housing has at least one feature for passive alignment and assembly of the laser and the filter. 
     
     
         66 . The packaged sensor device of  claim 36 , wherein the at least one optical lens is disposed between a bottom emitting surface of the laser and the filter to collimate the light. 
     
     
         67 . The packaged sensor device of  claim 36 , wherein the laser is a VCSEL having a substrate, and the substrate has a pattern of apertures on at least one side for the suppression of spontaneous emission of light. 
     
     
         68 . A sensor device for laser light emission comprising:
 at least one laser emitting a light from at least one aperture, the laser comprising a cavity and at least one mirror;   a detector;   a filter in a fixed position relative to the cavity;   at least one optical lens that approximately focuses a portion of the laser emission onto a target surface and couples a portion of any light reflected from the target surface back into the laser cavity; and   a beam splitter between the optical lens and the laser.   
     
     
         69 . The sensor device of  claim 68 , wherein the laser is a VCSEL. 
     
     
         70 - 94 . (canceled)