Laser diode module and depolarizer
AssigneeFujitsu Limited
InventorNobuhiro Fukushima
Life of this patent
Estimating the term…
Abstract
A compact, inexpensive laser diode module having a depolarizer function of converting linearly polarized light into unpolarized light. The laser diode module includes a laser diode; a polarization-maintaining optical fiber arranged so that an axis of polarization of the fiber forms an angle of 45.degree. with respect to a plane of polarization of incident light, the fiber having a length set so that an optical path difference between two polarization modes of transmitted light is greater than a coherence length of the incident light; and an optical coupling element for coupling emitting light from the laser diode to the polarization-maintaining optical fiber.
Claims7
A laser diode module comprising:
- a laser diode;
- a polarization-maintaining optical fiber arranged so that an axis of polarization of said fiber forms an angle of 45.degree. with respect to a plane of polarization of incident light, said fiber having a length set so that an optical path difference between two polarization modes of transmitted light is greater than a coherence length of said incident light;
- and
- optical coupling means for coupling emitting light from said laser diode to said polarization-maintaining optical fiber.
A laser diode module comprising:
- a laser;
- an optical fiber;
- optical coupling means for optically coupling said laser diode and said optical fiber;
- and
- a birefringent crystal means provided between said laser diode and said optical fiber and arranged so that an optic axis of said birefringent crystal means forms an angle of 45.degree. with respect to a plane of polarization of incident light, said optic axis being substantially perpendicular to a propagating direction of said incident light, said birefringent crystal means being set so that an optical path difference between an ordinary ray and an extraordinary ray is greater than a coherence length of said incident light.
A depolarizer for converting incident linearly polarized light into unpolarized light and outputting said unpolarized light, comprising:
- an input port on which said linearly polarized light is incident;
- optical rotating means formed of an optical rotatory power substance and set so that an optical path difference between left circularly polarized light and right circularly polarized light is greater than a coherence length of said incident light;
- and
- an output port for emerging said unpolarized light from said optical rotating means.
Dependencies are inferred from the claim text.