Oscillation polarization selective semiconductor laser and optical communication system using the same
AssigneeCanon Kabushiki Kaisha
InventorsMamoru Uchida, Toshihiko Ouchi
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Abstract
An oscillation polarization selective semiconductor laser that switches oscillation polarization modes between two different polarization modes includes a laser structure on a substrate. An active layer of the laser structure includes plural sets of quantum wells and barriers. The structure of at least one set of quantum wells and the barriers is different from the other sets so that the gain spectra generated in the active layer for induced mutually perpendicular propagation modes are selectively controlled by controlling the carrier density injected into the active layer. The oscillation polarization selective semiconductor laser may be used as a light source in optical communication systems.
Claims24
An oscillation polarization selective semiconductor laser for switching an oscillation polarization mode between two different polarization modes, said semiconductor laser comprising:
- a distributed reflector;
- and
- an active layer, said active layer having at least two quantum well structures, each of which includes a quantum well and barriers, and a bandgap of a quantum well of one of said quantum well structures being different from a bandgap of a quantum well of the other of said quantum well structures such that a distribution of gain spectra generated in said active layer for said two different polarization modes induced in a layer structure of said laser is varied by varying a density of carriers injected into said active layer.
An optical communication system for transmitting a signal from a transmitter side to a receiver side over a transmission line, said communication system comprising:
- an oscillation polarization selective semiconductor laser for switching an oscillation polarization mode between two different polarization modes, said semiconductor laser including a distributed reflector and an active layer, said active layer having at least two quantum well structures each of which includes a quantum well and barriers, and a bandgap of a quantum well of one of said quantum well structures being different from a bandgap of a quantum well of the other of said quantum well structures such that a distribution of gain spectra generated in said active layer for said two different polarization modes induced in a layer structure of said laser is varied by varying a density of carriers injected into said active layer;
- and
- a polarizer disposed in front of a light emission end surface of said semiconductor laser for selecting only a signal having a predetermined polarization mode.
A method for driving an oscillation polarization selective semiconductor laser comprising a distributed reflector and an active layer having at least two quantum well structures, each of which includes a quantum well and barriers and a band gap of a quantum well of one of said quantum well structures being different from a band gap of a quantum well of the other of said quantum well structures, and for switching an oscillation polarization mode between two different polarization modes, said method comprising steps of:
- oscillating the laser, by injecting carriers into said active layer, in one of said two different polarization modes;
- and
- changing a density of the carriers to be injected into said active layer,
- wherein a distribution of gain spectra corresponding to said two different polarization modes is varied by changing said density of the carriers and the laser is oscillated in the other of said two different polarization modes.
Dependencies are inferred from the claim text.