Wavelength selective optical couplers

An optical waveguide coupler comprising:

• (a) a first and second waveguide, said first and second waveguides being merged along a predetermined length to form an interaction region in which no substantial wavelength insensitive coupling of light from said first waveguide to said second waveguide occurs;
• (b) a diffraction grating in the interaction region.

An optical fiber comprising

• (a) a core,
• (b) a substantially doped cladding concentric with and encompassing the core, the cladding being photosensitized by the dopant such that actinic illumination of exposure <1 kJ/cm.sup.2 impresses an index of refraction change >10.sup.-5 in the doped cladding.

A waveguide coupler comprising:

• (a) a multiplicity of waveguides greater than two longitudinally merged in a central interaction region into a single shared waveguide,
• (b) said waveguides remaining substantially optically independent over a substantial wavelength range.
• (c) said interaction region having one or more diffraction gratings which couple light between the multiplicity of waveguides at one or more particular wavelengths.

A device for adding a channel at one or more particular wavelengths from a second optical waveguide to a first optical waveguide transmitting a number of wavelengths comprising:

• a grating assisted mode coupler connected to both optical waveguides, said coupler including one or more diffraction gratings that are transversely asymmetric, the periods of said diffraction gratings being chosen to redirect the added channel of said particular wavelengths from the second optical waveguide into said first optical waveguide.

A device for dropping a channel at one or more particular wavelengths from a first optical waveguide to a second optical waveguide comprising:

• a grating assisted mode coupler connected to both optical waveguides, said coupler including one or more diffraction gratings that are transversely asymmetric, the periods of said diffraction gratings being chosen to redirect the dropped channel of said particular wavelengths from the first optical waveguide into said second optical waveguide.

A wavelength dependent loss element for optical wave energy comprising:

• a grating assisted mode coupler, including one or more diffraction gratings having predetermined modulation to generate the desired wavelength dependent loss in the wave energy at selected wavelengths.

A device for demultiplexing a multitude of signal channels at particular wavelengths from an input waveguide to different ones of a multitude of output waveguides, including a multitude of grating assisted mode couplers, each possessing a diffraction grating whose period is chosen to redirect a signal channel of a selected wavelength from said input waveguide into one of said output waveguides.

A device for multiplexing a multitude of channels at particular wavelengths from a multitude of input waveguides to an output waveguide including a multitude of grating assisted mode couplers, each possessing a diffraction grating whose period is chosen to redirect a channel of said particular wavelength from one of said input waveguides into said output waveguide.

An optical waveguide propagation device with adjacent, longitudinal waveguide sections with different beam propagation characteristics comprising:

• (a) a first section with dissimilar first and second waveguides, and
• (b) a second section joined to the first, wherein the first and second waveguides are longitudinally merged to form a single waveguide including a diffraction grating.

A single mode photosensitive cladding optical fiber comprising

• (a) a core of about 8 to 9 .mu.m diameter,
• (b) a cladding of about 125 .mu.m diameter concentric with and encompassing said core,
• (c) cladding material including sufficient doping to change the index of refraction of the doped cladding material by >10.sup.-5 upon subjecting to actinic illumination of exposure <1 kJ cm.sup.-2.

An optical waveguide device comprising an optical waveguide containing a transversely asymmetric index of refraction grating within the light confining region of the optical waveguide,

• said grating being configured to substantially couple optical energy from a single forward propagating optical mode to a backward propagating, orthogonal optical mode at a particular wavelength.

A wavelength selective optical energy controlling device comprising:

• at least two optical waveguides each having a core and cladding for confining optical energy, and
• the optical waveguides including an intermediate wave interchange region in which reduced diameter waveguide lengths are merged longitudinally into a composite section in which waves are propagated substantially in the original cladding material, the cladding material therein including an index of refraction grating.

A wave interchange region supporting multiple wavelengths in a forward propagating mode, comprising

• a pair of reduced dimension and physically merged optical waveguide fibers, each having its transverse dimension reduced such that waves substantially escape the material comprising the original cores and propagate substantially in the material comprising the original cladding, the physically merged waveguides forming a common waveguide section,
• the common waveguide section being photosensitized and including an index of refraction grating having a periodicity reflecting light at a selected wavelength.

A wavelength selective device for use in optical wave propagation, comprising

• a pair of optical waveguides each having a central core and cladding, the two waveguides being united along a merged waist region of substantially reduced cross section and including a grating in the material which originally comprised the cladding of said optical waveguides, the two waveguides being tapered down to form the merged region.

A wavelength selective device for controlling optical wave propagation composed of at least two optical waveguides which support multiple wavelengths, including a selected wavelength in a forward transmission mode, the device comprising:

• a merged region uniting the two waveguides and forming a common propagation section in which wave energy is propagated in two orthogonal modes extending outwardly from the merged region, and
• a diffraction grating in the merged region interacting with the forward transmission mode to redirect the optical wave at the selected wavelength into a backward transmission mode.

A wave interchange region supporting multiple wavelengths in a forward and backward propagating mode in optical waveguides having original cores and claddings about the cores, comprising:

• a pair of optical fiber lengths fused and elongated to a reduced diameter waist region such that V numbers of original single mode cores are reduced by a factor greater than 2 in the vicinity of the reduced diameter waist region, such that optical waves propagated along said reduced diameter waist region substantially escape the material comprising the original cores and propagate substantially in the material comprising the original cladding,
• wherein the reduced diameter waist region is photosensitive, and the reduced diameter waist region includes a diffraction grating having a periodicity reflecting a selected wavelength.

A wavelength selective optical energy controlling device comprising:

• at least two optical waveguides each having a core material and cladding material for confining propagating optical energy, and
• an intermediate wave interchange region characterized by reduced diameter waveguide lengths integral with the optical waveguides and merged longitudinally into a composite section in which waves overlap in a substantially non-evanescent manner, the cladding material of reduced diameter in said composite section including an index of refraction grating.

A wavelength selective optical energy controlling device comprising:

• at least two optical waveguides each having a core and cladding for confining propagating optical energy, and
• an intermediate wave interchange region characterized by reduced diameter waveguide lengths merged longitudinally into a composite section in which waves are propagated substantially in what was originally the material comprising the cladding, and the cladding material including an index of refraction grating,
• said intermediate wave interchange region supporting orthogonal supermodes which transform adiabatically and in a one-to-one manner into different optical modes of the output optical waveguides.

A device comprised of a first and second optical waveguide joined together to form a merged region;

• the merged region introducing no substantial wavelength insensitive coupling from the first optical waveguide to the second optical waveguide;
• the diffraction grating contained within the merged region introducing wavelength selective coupling from the first waveguide to the second waveguide.

A non-evanescent waveguide coupler comprising:

• (a) a first and second waveguide, said first and second waveguides being merged along a predetermined length to form a potential interaction region;
• (b) a diffraction grating in the interaction region, the period of said grating being chosen to promote coupling of optical energy from the first waveguide into the second waveguide.