Polarization-mode selective semiconductor laser with a bending channel stripe, apparatus including the same and optical communication system using the same

A light source apparatus comprising:

• a polarization-mode selective semiconductor laser, said semiconductor laser emitting light in a first polarization mode under a first stimulated condition and light in a second polarization mode under a second stimulated condition and including:
• a semiconductor laser structure including an active layer for generating gain spectra for the first and second different polarization modes, said laser structure including a first distributed feedback reflector portion with a first channel stripe and a second distributed feedback reflector portion with a second channel stripe connected to said first stripe channel, said first distributed feedback reflector portion and said second distributed feedback reflector portion being serially arranged in a cavity direction of said semiconductor laser;
• and
• a diffraction grating, said diffraction grating being formed with a substantially uniform pitch and a substantially uniform grating vector over said first and second distributed feedback reflector portions,
• wherein said first and second stripe channels are bent relative to each other so as to make the first polarization mode dominant in said first distributed feedback reflector portion and make the second polarization mode dominant in said second distributed feedback reflector portion;
• and
• polarization-mode selecting means for selecting light in one of the first and second polarization modes emitted from said semiconductor laser.

An optical communication system for communicating over a light transmission medium that transmits a signal from a transmitter side to a receiver side, said optical communication system comprising:

• a transmitter, said transmitter including:
• a polarization-mode selective semiconductor laser, said semiconductor laser emitting light in a first polarization mode under a first stimulated condition and light in a second polarization mode under a second stimulated condition and including:
• a semiconductor laser structure including an active layer for generating gain spectra for the first and second different polarization modes, said laser structure including a first distributed feedback reflector portion with a first channel stripe and a second distributed feedback reflector portion with a second channel stripe connected to said first stripe channel, said first distributed feedback reflector portion and said second distributed feedback reflector portion being serially arranged in a cavity direction of said semiconductor laser;
• and
• a diffraction grating, said diffraction grating being formed with a substantially uniform pitch and a substantially uniform grating vector over said first and second distributed feedback reflector portions,
• wherein said first and second stripe channels are bent relative to each other so as to make the first polarization mode dominant in said first distributed feedback reflector portion and make the second polarization mode dominant in said second distributed feedback reflector portion;
• polarization-mode selecting means for selecting one of light in the first and second polarization modes emitted from said semiconductor laser;
• and
• control means for controlling and driving said semiconductor laser such that the polarization mode of the light emitted from said semiconductor laser is changed in accordance with a signal input into said semiconductor laser;
• and
• a receiver for receiving a signal from said transmitter.

An optical communication method for communicating over a light transmission medium that transmits a signal from a transmitter side to a receiver side, said optical communication method comprising the steps of:

• preparing a transmitter, the transmitter including:
• a polarization-mode selective semiconductor laser, the semiconductor laser emitting light in a first polarization mode under a first stimulated condition and light in a second polarization mode under a second stimulated condition and including:
• a semiconductor laser structure including an active layer for generating gain spectra for the first and second different polarization modes, the laser structure including a first distributed feedback reflector portion with a first channel stripe and a second distributed feedback reflector portion with a second channel stripe connected to the first stripe channel, the first distributed feedback reflector portion and the second distributed feedback reflector portion being serially arranged in a cavity direction of the semiconductor laser;
• and
• a diffraction grating, the diffraction grating being formed with a substantially uniform pitch and a substantially uniform grating vector over the first and second distributed feedback reflector portions,
• wherein the first and second stripe channels are bent relative to each other so as to make the first polarization mode dominant in the first distributed feedback reflector portion and make the second polarization mode dominant in the second distributed feedback reflector portion;
• polarization-mode selecting means for selecting light in one of the first and second polarization modes emitted from the semiconductor laser;
• and
• control means for controlling and driving the semiconductor laser such that the polarization mode of the light emitted from the semiconductor laser is changed in accordance with a signal input into the semiconductor laser;
• causing the transmitter to transmit an optical signal whose amplitude is modulated in accordance with the signal input into the semiconductor laser;
• and
• transmitting the optical signal through the light transmission medium toward the receiver side.