Two-section distributed Bragg reflector laser

A semiconductor laser, comprising:

• a gain section;
• a facet located at an interface between said gain section and air, said facet emitting output laser light at a wavelength;
• a Bragg section, formed adjacent to said gain section and coupled to said gain section via a second interface, wherein said second interface is quantum well intermixed to render said second interface substantially anti-reflecting at said wavelength;
• and
• a photodiode adjacent to said facet and configured to monitor said wavelength;
• said Bragg section comprising a distributed reflecting structure having a side-mode suppression ratio (SMSR) of 35 dB or more and a length substantially greater than required to ensure single longitudinal mode operation of the laser, thereby in use substantially suppressing optical feedback from a second facet at an interface between said Bragg section and air.

A semiconductor laser, comprising:

• a gain section;
• a facet located at an interface between said gain section and air, said facet emitting output laser light at a wavelength;
• a Bragg section, formed adjacent to said gain section and coupled to said gain section via a second interface, wherein said second interface is quantum well intermixed to render said second interface substantially anti-reflecting at said wavelength, said Bragg section comprising a distributed reflecting structure having a length selected to substantially suppress optical feedback from a second facet at an interface between said Bragg section and air;
• an electrode coupled to said Bragg section, for injecting electrical current into said Bragg section, the injected current changing the Bragg wavelength of said distributed reflecting structure configured to tune said wavelength;
• and
• a photodiode adjacent to said facet and configured to monitor said wavelength.