Multiplexer and demultiplexer for single mode optical fiber communication links

A bi-directional optical apparatus, of the type which is used in connection with optical beams generated by a plurality of laser sources and which is carried by optical fibers, the apparatus comprising:

• a. a diffraction grating;
• b. means for shaping the optical beams;
• and
• c. means for adjusting the polarization direction of the optical beams, whereby the diffraction grating efficiency is improved and the polarization dependent loss is minimized;

A bi-directional optical apparatus, of the type which is used in connection with optical signals generated by a plurality of laser sources and which is carried by optical fibers, the apparatus comprising:

• a. an optical fiber;
• b. multiplexer means for spatially combining the optical signals from several laser sources, each of which is a different wavelength, and launching the spatially combined optical signals into a single optical fiber to form a wavelength division multiplexed optical signal;
• and
• c. demultiplexer means for spatially separating the different wavelengths from the single optical fiber carrying wavelength division multiplexed optical signals and launching each of the different wavelengths into a separate optical fiber, wherein the multiplexer and demultiplexer means are comprised of identical components.

A bi-directional device comprising:

• a. a diffraction grating;
• b. means for shaping the optical beams;
• and
• c. means for adjusting the polarization direction of the optical beams, whereby the diffraction grating efficiency is improved and the polarization dependent loss is minimized,
• d. wherein the device may be used as both:
• i. a multiplexer to spatially combine the optical beams from several laser sources, each of which is a different wavelength and launch the spatially combined laser beams into a single optical fiber;
• ii. a demultiplexer to spatially separate the different wavelengths of a wavelength division multiplexed optical link and launch each of the different wavelengths into a different optical fiber.

A method of demultiplexing a plurality of light signals carried by an optical fiber comprising the steps of:

• a. collimating the light exiting an optical fiber end face;
• b. splitting the plurality of optical wavelength signals into two beams;
• c. rotating the polarization of either the p polarized or s polarized beam;
• d. expanding the diameter of the collimated beams in the direction of the polarization;
• e. diffracting each of the different wavelength beams into a different angular direction relative to a defined direction;
• f. reducing the expanded diameter of the collimated beams in the direction of the polarization;
• g. recombining the two optical beams at each wavelength into a single beam for each wavelength signal, and wherein the recombined beam for each wavelength has two mutually perpendicular polarization components and is propagating in a different angular direction relative to an optic axis;
• h. focusing the optical wavelength signals to a different spatial location along a line in the focal plane of the focusing means;
• and
• i. receiving the focused signals and launching the individual signals into separate optical fibers.

An optical fiber transmission apparatus, the apparatus comprising:

• a. a plurality of laser sources for generating optical beams;
• b. a first optical transmission fiber;
• c. multiplexer means for spatially combining the optical beams from the laser sources, each of which is a different wavelength, and launching the spatially combined optical beams into the optical transmission fiber to form a wavelength division multiplexed optical signal, wherein the multiplexer means includes:
• i. a diffraction grating;
• ii. means for-fine tuning the propagation direction of the optical beams;
• and
• iii. means for adjusting the polarization direction of the optical beams, whereby the diffraction grating efficiency is improved and the polarization dependent loss is minimized;
• d. a plurality of second optical fibers;
• and
• e. demultiplexer means for spatially separating the different wavelengths from the optical transmission fiber and launching each of the different wavelengths into separate second optical fibers, wherein the demultiplexer means includes:
• i. a diffraction grating;
• ii. means for fine tuning the propagation direction of the optical beams;
• and
• iii. means for adjusting the polarization direction of the optical beams, whereby the diffraction grating efficiency is improved and the polarization dependent loss is minimized.

A bi-directional optical apparatus, of the type which is used in connection with optical beams generated by a plurality of laser sources and which is carried by optical fibers, the apparatus comprising:

• a. a diffraction grating;
• b. means for fine tuning the propagation direction of the optical beams;
• and
• c. means for adjusting the polarization direction of the optical beams, whereby the diffraction grating efficiency is improved and the polarization dependent loss is minimized;

A bi-directional device comprising:

• a. a diffraction grating;
• b. means for fine tuning the propagation direction of the optical beams;
• and
• c. means for adjusting the polarization direction of the optical beams, whereby the diffraction grating efficiency is improved and the polarization dependent loss is minimized,
• d. wherein the device may be used as both:
• i. a multiplexer to spatially combine the optical beams from several laser sources, each of which is a different wavelength and launch the spatially combined laser beams into a single optical fiber;
• ii. a demultiplexer to spatially separate the different wavelengths of a wavelength division multiplexed optical link and launch each of the different wavelengths into a different optical fiber.

A method of demultiplexing a plurality of light signals carried by an optical fiber comprising the steps of:

• a. collimating the light exiting an optical fiber end face;
• b. splitting the plurality of optical wavelength signals into two beams;
• c. rotating the polarization of either the p polarized or s polarized beam;
• d. diffracting each of the different wavelength beams into a different angular direction relative to a defined direction;
• e. recombining the two optical beams at each wavelength into a single beam for each wavelength signal, and wherein the recombined beam for each wavelength has two mutually perpendicular polarization components and is propagating in a different angular direction relative to an optic axis;
• f. focusing the optical wavelength signals to a different spatial location along a line in the focal plane of the focusing means;
• and
• g. receiving the focused signals and launching the individual signals into separate optical fibers.