Low white frequency noise tunable semiconductor laser source

A low white frequency noise tunable semiconductor laser source, comprising:

• a semiconductor laser assembly comprising at least one single-mode semiconductor laser generating a laser beam having a frequency and a laser tuning mechanism coupled to the at least one single-mode semiconductor laser for tuning the frequency of the laser beam generated thereby over a spectral range of interest;
• an optical filter in a path of the laser beam and having multiple spectral features distributed over the entire spectral range of interest, each spectral feature being a transmission peak and having a narrow spectral range, wherein the optical filter comprises a Bragg grating having a sampled phase profile including a π shift at a center thereof, said Bragg grating having a spectral response including a plurality of reflection channels and a narrow transmission notch in each of said reflection channels, each of said narrow transmission notches defining one of said spectral features;
• and
• a locking mechanism controllable for locking a spectral alignment between the frequency of the laser beam and any selected one of the spectral features of the optical filter.

A low white frequency noise tunable semiconductor laser source, comprising:

• a semiconductor laser assembly comprising at least one single-mode semiconductor laser generating a laser beam having a frequency and a laser tuning mechanism coupled to the at least one single-mode semiconductor laser for tuning the frequency of the laser beam generated thereby over a spectral range of interest;
• an optical filter in a path of the laser beam and having multiple spectral features distributed over the entire spectral range of interest, each spectral feature being a transmission peak and having a narrow spectral range, wherein the optical filter comprises a plurality of grating regions provided along a waveguiding axis of an optical medium, consecutive ones of said plurality of grating regions being separated by a corresponding grating-free central region extending therebetween, the plurality of grating regions defining together a Bragg grating having a sampled phase profile including a π phase shift between each of said plurality of grating regions, said Bragg grating having a spectral response including a plurality of reflection channels and a flat-top narrow transmission notch in each of said reflection channels, each of said flat-top narrow transmission notches defining one of said spectral features;
• and
• a locking mechanism controllable for locking a spectral alignment between the frequency of the laser beam and any selected one of the spectral features of the optical filter.

A low white frequency noise tunable semiconductor laser source, comprising:

• a semiconductor laser assembly comprising at least one single-mode semiconductor laser generating a laser beam having a frequency and a laser tuning mechanism coupled to the at least one single-mode semiconductor laser for tuning the frequency of the laser beam generated thereby over a spectral range of interest;
• an optical filter in a path of the laser beam and having multiple spectral features distributed over the entire spectral range of interest, each spectral feature having a narrow spectral range, wherein the optical filter comprises an all-fiber or bulk Fabry-Perot interferometer;
• and
• a locking mechanism controllable for locking a spectral alignment between the frequency of the laser beam and any selected one of the spectral features of the optical filter.

A white frequency noise tunable semiconductor laser source, comprising:

• a semiconductor laser assembly comprising at least one single-mode semiconductor laser generating a laser beam having a frequency and a laser tuning mechanism coupled to the at least one single-mode semiconductor laser for tuning the frequency of the laser beam generated thereby over a spectral range of interest;
• an optical filter in a path of the laser beam and having multiple spectral features distributed over the entire spectral range of interest, each spectral feature having a narrow spectral range;
• a locking mechanism controllable for locking a spectral alignment between the frequency of the laser beam and any selected one of the spectral features of the optical filter;
• and
• a filter tuning mechanism coupled to the optical filter for tuning a position of the selected spectral feature.

A low white frequency noise tunable semiconductor laser source, comprising:

• a semiconductor laser assembly comprising at least one single-mode semiconductor laser generating a laser beam having a frequency and a laser tuning mechanism coupled to the at least one single-mode semiconductor laser for tuning the frequency of the laser beam generated thereby over a spectral range of interest;
• an optical filter in a path of the laser beam and having multiple spectral features distributed over the entire spectral range of interest, each spectral feature having a narrow spectral range;
• and
• a locking mechanism controllable for locking a spectral alignment between the frequency of the laser beam and any selected one of the spectral features of the optical filter, the locking mechanism comprising:
• a modulating assembly for imposing a modulation on the spectral alignment between the frequency of the laser beam with the selected spectral feature of the optical filter, the optical filter thereby providing a modulated feedback signal related to an error in said spectral alignment;
• and
• a feed back loop for detecting the feedback signal, comparing the same with said modulation and generating from said comparing a correction signal for correcting said spectral alignment.

A low white frequency noise tunable semiconductor laser source, comprising:

• a semiconductor laser assembly comprising at least one single-mode semiconductor laser generating a laser beam having a frequency and a laser tuning mechanism coupled to the at least one single-mode semiconductor laser for tuning the frequency of the laser beam generated thereby over a spectral range of interest;
• an optical filter in a path of the laser beam and having multiple spectral features distributed over the entire spectral range of interest, each spectral feature having a narrow spectral range, wherein the optical filter is a polarization-sensitive filter having a first spectral response for light in a first polarization state and a second spectral response for light in a second polarization state orthogonal to the first polarization state, each of said first and second spectral responses comprises said spectral features, corresponding spectral features in said first and second responses being partially detuned, the laser beam having first and second polarization components in said first and second polarization states, respectively;
• and
• a locking mechanism controllable for locking a spectral alignment between the frequency of the laser beam and any selected one of the spectral features of the optical filter, the locking mechanism using one of said first and second components for locking said spectral alignment.