Tunable optical device

A tunable optical device comprising:

• a housing;
• first and second optical waveguides extending into the housing so as to define a space between said waveguides, said space defining an optical path between the waveguides;
• an optical resonant cavity extending across said space, said space containing a liquid crystal material to permit tuning of the cavity;
• and
• alignment structure to orientate the liquid crystal material so that it responds to an applied electric field, wherein the alignment structure is disposed outside the optical path on at least one structure defining said space.

A polarisation insensitive tunable optical device comprising:

• a substrate and a superstrate;
• first and second optical fibres sandwiched between said substrate and said superstrate so as to define a space between said fibres;
• an optical resonant cavity extending across said space, said space containing a liquid crystal material to permit tuning of the cavity;
• and
• an alignment layer disposed on at least one of said substrate and said superstrate to orientate the liquid crystal material so that it responds to an applied electric field, wherein the alignment layer is disposed on at least one of the substrate and the superstrate, said alignment layer comprising first and second parts which orientate the liquid crystal material in a direction generally parallel to the length of the fibres and a third part, between said first and second parts, which orientates the liquid crystal material in a direction transverse to the length of the fibres.

An array of individually tunable optical filters, including a substrate and a superstrate, wherein each filter comprises:

• first and second opposed optical fibres located between the substrate and the superstrate and aligned by grooves in the substrate and the superstrate;
• a liquid crystal filled space between the ends of the first and second fibres;
• an optical resonant cavity extending across the space;
• and
• an electrode formed on at least one of the substrate and the superstrate to permit individual tuning of the cavity, wherein an alignment layer is disposed on at least one of said substrate and said superstrate.

A tunable optical device comprising:

• a substrate and a superstrate;
• first and second elongate optical fibres sandwiched between said substrate and said superstrate so as to define a space between said waveguides;
• an optical resonant frequency cavity extending across said space, said space containing a liquid crystal material to permit tuning of the frequency of said cavity;
• and
• alignment means to orientate the liquid crystal material so that it responds to an applied electric field,
• wherein the alignment means is disposed on at least one of the substrate and the superstrate.

A frequency-tunable optical device comprising:

• a housing;
• a first and second optical waveguides extending into the housing so as to define a space between said waveguides, said space defining an optical path between the waveguides;
• an optical resonant-frequency cavity extending across said space, said space containing a liquid crystal material to permit tuning the frequency of the cavity;
• and
• alignment structure to orientate the liquid crystal material so that it responds to an applied electric field,
• wherein the alignment structure is disposed outside the optical path on at least one structure defining said space.

A frequency-tunable optical device comprising:

• a substrate and a superstrate;
• first and second elongate optical fibres sandwiched between said substrate and said superstrate so as to define a space between said fibres,
• said space containing a liquid crystal material having an optical fast axis, the orientation of said fast axis at least in part determining a frequency-dependent response of the device;
• and
• alignment means disposed on at least one of said substrate and said superstrate to orientate the liquid crystal material so that it responds to an applied electric field,
• wherein the alignment means are arranged to orientate the liquid crystal material in a direction transverse to the length of said fibres,
• whereby to permit rotation of said fast axis of said liquid crystal material.

An array of individually frequency-tunable optical filters disposed between:

• a substrate and a superstrate, wherein each filter comprises:
• first and second opposed optical fibres located between the substrate and the superstrate and aligned by grooves in the substrate and the superstrate;
• a liquid crystal filled space between the ends of the first and second fibres;
• an optical resonant frequency cavity extending across the space;
• and
• an electrode formed on at least on of the substrate and the superstrate to permit individual tuning of the frequency of the cavity, wherein an alignment layer is disposed on at least one of said substrate and said superstrate.