Wavelength monitoring apparatus

A wavelength monitoring device characterized in that said device comprises:

• a semiconductor laser for emitting an optical signal that travels along a laser optical axis;
• a birefringence crystalline unit provided with a first birefringence crystal having an optical axis inclined against a plane perpendicular to the laser optical axis and toward the laser optical axis, and a second birefringence crystal arranged in series with said first birefringence crystal with respect to the laser optical axis, said second birefringence crystal having an optical axis inclined against a plane perpendicular to the laser optical axis and toward the laser optical axis, said birefringence crystalline unit receiving the optical signal emitted from said semiconductor laser, said second birefringence crystal providing a phase shift due to a temperature change thereof to the optical signal passing therethrough so that a phase shift provided to the optical signal passing through said first birefringence crystal due to a temperature change of said first birefringence crystal can be cancelled, and said birefringence crystalline unit then outputting an optical signal having a polarized wave component of intensity corresponding to a wavelength of the received optical signal;
• and
• a detecting means for detecting and monitoring an intensity of the optical signal output from said birefringent crystalline unit.

A wavelength monitoring device characterized in that said comprises:

• a semiconductor laser for emitting an optical signal that travels along a laser optical axis;
• a birefringence crystal having a cut-out surface parallel to a plane perpendicular to the laser optical axis, and an optical axis oriented in a direction determined by inclining a directional vector inclined against a first axis in the plane toward a direction of the laser optical axis by a crystal cut-out angle, said birefringence crystal being rotated about the first axis by only a certain adjustment angle so that a normal to the crystal cut-out surface is inclined against the direction of the laser optical axis and toward a direction of a second axis perpendicular to both the first axis and the laser optical axis by only the certain adjustment angle, and said birefringence crystal receiving the optical signal emitted from said semiconductor laser and outputting an optical signal having a polarized wave component of intensity corresponding to a wavelength of the received optical signal;
• and
• a detecting means for detecting and monitoring an intensity of the optical signal output from said birefringent crystal.

A wavelength monitoring device characterized in that said device comprises:

• a semiconductor laser for emitting an optical signal that travels along a laser optical axis thereof;
• a birefringence crystalline unit provided with a first birefringence crystal and a second birefringence crystal arranged in series with said first birefringence crystal with respect to the laser optical axis, said first birefringence crystal having a cut-out surface parallel to a plane perpendicular to the laser optical axis, and an optical axis oriented in a direction determined by inclining a directional vector inclined against a first axis in the plane toward a direction of the laser optical axis by a first crystal cut-out angle, said first birefringence crystal being rotated about the first axis by only a first adjustment angle so that a normal to the crystal cut-out surface is inclined against the direction of the laser optical axis and toward a direction of a second axis perpendicular to both the first axis and the laser optical axis by only the first adjustment angle, said second birefringence crystal having a cut-out surface parallel to a plane perpendicular to the laser optical axis, and an optical axis oriented in a direction determined by inclining a directional vector inclined against the first axis in the plane toward a direction of the laser optical axis by a second crystal cut-out angle, said second birefringence crystal being rotated about the first axis by only a second adjustment angle so that a normal to the crystal cut-out surface is inclined against the direction of the laser optical axis and toward the direction of the second axis by only the second adjustment angle, said birefringence crystalline unit receiving the optical signal emitted from said semiconductor laser, said second birefringence crystal providing a phase shift due to a temperature change thereof to the optical signal passing therethrough so that a phase shift provided to the optical signal passing through said first birefringence crystal due to a temperature change of said first birefringence crystal can be cancelled, and said birefringence crystalline unit then outputting an optical signal having a polarized wave component of intensity corresponding to a wavelength of the received optical signal;
• and
• a detecting means for detecting and monitoring an intensity of the optical signal output from said birefringent crystalline unit.

A wavelength monitoring device characterized in that said device comprises:

• a semiconductor laser for emitting an optical signal that travels along a laser optical axis thereof;
• a birefringent crystal unit having a length in a direction of the laser optical axis which changes along a specific direction that differs from the direction of the laser optical axis, said birefringent crystal unit receiving the optical signal emitted from said semiconductor laser and being arranged at a specific position in a specific direction so as to output an optical signal having a polarized wave component of intensity corresponding to a wavelength of the optical signal on a condition that the intensity of the polarized wave component changes dependently upon a change in the wavelength of the optical signal;
• and
• a detecting means for detecting and monitoring the intensity of the polarized wave component of the optical signal output from said birefringent crystal unit.