Semi-integrated designs with in-waveguide mirrors for external cavity tunable lasers

A tunable laser, comprising:

• a base;
• an integrated structure operatively coupled to the base, having a substantially non-reflective front facet and rear facet optically coupled via a waveguide passing therethrough, the integrated structure further including:
• a gain section to emit a plurality of photons in response to a first electrical input, having a facet defining the rear facet of the integrated structure;
• a modulator section, optically coupled to the gain section via a portion of the waveguide, to modulate an optical output generated by the tunable laser passing through a portion of the waveguide disposed in the modulator section in response to a second electrical input, and having a facet defining the front facet of the integrated structure;
• and
• a partially-reflective in-waveguide mirror formed within a mirror section comprising the portion of the waveguide disposed between the gain section and the modulator section;
• a reflective element, operatively coupled to the base and disposed opposite the substantially non-reflective rear facet to form an external cavity;
• and
• a tunable filter including at least one optical element operatively coupled to the base and disposed in the external cavity.

A tunable external cavity diode laser (ECDL), comprising:

• a base;
• an integrated structure operatively coupled to the base, having a substantially non-reflective front facet and rear facet optically coupled via a waveguide passing therethrough, the integrated structure further including:
• a gain section to emit a plurality of photons in response to a first electrical input,
• a phase control section disposed adjacent to the gain section, to modulate an optical path length of a portion of the waveguide passing through the phase control section in response to a second electrical input;
• a modulator section, optically coupled to the gain section and phase control section via a portion of the waveguide, to modulate an optical output generated by the tunable laser passing through a portion of the waveguide disposed in the modulator section in response to a third electrical input, and having a facet defining the front facet of the integrated structure;
• and
• a partially-reflective in-waveguide mirror formed within a mirror section comprising the portion of the waveguide disposed between the modulator section and one of the gain section and phase control section;
• a reflective element, operatively coupled to the base and disposed opposite the substantially non-reflective rear facet to form an external cavity;
• and
• a tunable filter including at least one optical element operatively coupled to the base and disposed in the external cavity.

A telecommunication switch comprising:

• a plurality of fiber line cards, each including,
• a multi-stage multiplexer/demultiplexer;
• a circulator bank, comprising a plurality of circulators operatively coupled to the multi-stage multiplexer/demultiplexer;
• a receiver bank, comprising a plurality of receivers operatively coupled to respective circulators;
• and
• a transmitter bank, comprising a plurality of transmitters operatively coupled to respective circulators, each transmitter comprising at tunable external cavity diode laser (ECDL), including:
• a base;
• an integrated structure operatively coupled to the base, having a substantially non-reflective front facet and rear facet optically coupled via a waveguide passing therethrough, the integrated structure further including:
• a gain section to emit a plurality of photons in response to a first electrical input,
• a phase control section disposed adjacent to the gain section, to modulate an optical path length of a portion of the waveguide passing through the phase control section in response to a second electrical input;
• a modulator section, optically coupled to the gain section and phase control section via a portion of the waveguide, to modulate an optical output generated by the tunable laser passing through a portion of the waveguide disposed in the modulator section in response to a third electrical input, and having a facet defining the front facet of the integrated structure;
• and
• a partially-reflective mirror formed within a mirror section comprising the portion of the waveguide disposed between the modulator section and one of the gain section and phase control section;
• a reflective element, operatively coupled to the base and disposed opposite the substantially non-reflective rear facet to form an external cavity;
• and
• a tunable filter including at least one optical element operatively coupled to the base and disposed in the external cavity.

A method, comprising:

• fabricating an integrated structure having a waveguide passing therethrough, the waveguide having a waveguide core;
• defining one or more trenches through the waveguide core in a portion of the waveguide;
• and
• backfilling the one or more trenches with a backfill material having a different index of refraction than the waveguide core.