US 5,321,539 A · Liquid crystal Fabry-Perot etalon with glass spacer

Abstract

A tunable wavelength-selective filter includes a glass substrate, a transparent electrode layer, a highly reflective mirror, an alignment layer, a liquid crystal layer, another alignment layer, a transparent material layer whose refractivity index is substantially equal to that of the liquid crystal layer, another highly reflective mirror, another transparent electrode layer, and another glass substrate, which are stacked in this order. An etalon cavity of the filter includes two layers, the liquid crystal layer and the transparent material layer (such as a glass plate), which enables the cavity length to be increased without increasing absorption and scattering of the cavity. This makes it possible to narrow the FWHM, quicken the response time, and increase the transmittance of the filter. Applications for the filter include a double cavity structure tunable wavelength-selective filter of a wide tunable range, and a photodetector of a simple construction.

Claims44

Dependent claims

An electrically tunable wavelength-selective filter, comprising:

a first glass substrate;
a first transparent electrode layer;
a first highly reflective mirror;
a first alignment layer;
a liquid crystal layer;
a second alignment layer;
a transparent material layer whose refractive index is substantially equal to that of the liquid crystal of said liquid crystal layer;
a second highly reflective mirror;
a second transparent electrode layer;
and
a second glass substrate;
which are arranged in this sequence,
wherein said first and second highly reflective mirrors define an etalon cavity having an optical length and said transparent material layer is present to increase the optical length of the etalon cavity.

10 more elements

An electrically tunable wavelength-selective filter, comprising:

a first tunable liquid crystal wavelength-selective filter;
and
a second tunable liquid crystal wavelength-selective filter which is stacked on said first tunable liquid crystal wavelength-selective filter;
wherein said first tunable liquid crystal wavelength-selective filter includes
a first glass substrate;
a first transparent electrode layer;
a first highly reflective mirror;
a first alignment layer;
a first liquid crystal layer;
a second alignment layer;
a transparent material layer whose refractive index is substantially equal to that of the liquid crystal of said liquid crystal layer;
a second highly reflective mirror;
a second transparent electrode layer;
and
a second glass substrate;
which are arranged in this sequence,
wherein said first and second highly reflective mirrors define an etalon cavity having an optical length and said transparent material layer is present to increase the optical length of the etalon cavity, and
wherein said second tunable liquid crystal wavelength-selective filter includes
a third glass substrate;
a third transparent electrode layer;
a third highly reflective mirror;
a third alignment layer;
a second liquid crystal layer;
a fourth alignment layer;
a fourth highly reflective mirror;
a fourth transparent electrode layer;
and
a fourth glass substrate;
which are arranged in this sequence.

26 more elements

A photodetector for receiving an optical signal via an input optical fiber, comprising:

lensing means for collimating light transmitted through said input optical fiber;
a fiber connecting portion connecting said input optical fiber to said lensing means;
polarization beam separation means for polarization separating said light transmitted through said lensing means into a first polarization light beam and a second polarization light beam;
polarization rotation means for rotating the polarization of said second polarization light beam;
an electrically tunable liquid crystal wavelength-selective filter selectively transmitting said first and second polarization light beams;
a focusing lensing means for focusing said first and second polarization light beams transmitted through said electrically tunable liquid crystal wavelength-selective filter;
and
photodetecting means for detecting said first and second polarization light beams focused by said focusing lensing means,
wherein said electrically tunable liquid crystal wavelength-selective filter includes
a first glass substrate;
a first transparent electrode layer;
a first highly reflective mirror;
a first alignment layer;
a liquid crystal layer;
a second alignment layer;
a transparent material layer whose refractive index is substantially equal to that of the liquid crystal of said liquid crystal layer;
a second highly reflective mirror;
a second transparent electrode layer;
and
a second glass substrate;
which are arranged in this sequence, and
wherein said first and second highly reflective mirrors define an etalon cavity having an optical length and said transparent material layer is present to increase the optical length of the etalon cavity.

19 more elements

A photodetector for receiving an optical signal via an input optical fiber, comprising:

lensing means for collimating light transmitted through said input optical fiber;
a fiber connecting portion connecting said input optical fiber to said lensing means;
polarization beam separation means for polarization separating said light transmitted through said lensing means into a first polarization light beam and a second polarization light beam;
polarization rotation means for rotating the polarization of said second polarization light beam;
an electrically tunable liquid crystal wavelength-selective filter selectively transmitting said first and second polarization light beams;
a focusing lensing means for focusing said first and second polarization light beams transmitted through said electrically tunable liquid crystal wavelength-selective filter;
and
photodetecting means for detecting said first and second polarization light beams focused by said focusing lensing means;
wherein said electrically tunable liquid crystal wavelength-selective filter includes a first tunable liquid crystal wavelength-selective filter, and a second tunable liquid crystal wavelength-selective filter which is stacked on said first tunable liquid crystal wavelength-selective filter,
wherein said first tunable liquid crystal wavelength-selective filter includes
a first glass substrate;
a first transparent electrode layer;
a first highly reflective mirror;
a first alignment layer;
a first liquid crystal layer;
a second alignment layer;
a transparent material layer whose refractive index is substantially equal to that of the liquid crystal of said liquid crystal layer;
a second highly reflective mirror;
a second transparent electrode layer;
and
a second glass substrate;
which are arranged in this sequence,
wherein said first and second highly reflective mirrors define an etalon cavity having an optical length and said transparent material layer is present to increase the optical length of the etalon cavity, and
wherein said second tunable liquid crystal wavelength-selective filter includes
a third glass substrate;
a third transparent electrode layer;
a third highly reflective mirror;
a third alignment layer;
a second liquid crystal layer;
a fourth alignment layer;
a fourth highly reflective mirror;
a fourth transparent electrode layer;
and
a fourth glass substrate;
which are arranged in this sequence.

32 more elements

A photodetector for receiving an optical signal via an input optical fiber, comprising:

lensing means for collimating light transmitted through said input optical fiber;
a fiber connecting portion connecting said input optical fiber to said lensing means;
polarization beam separation mans for polarization separating said light transmitted through said lensing means into a first polarization light beam and a second polarization light beam;
polarization rotation means for rotating the polarization of said second polarization light beam;
an electrically tunable liquid crystal wavelength-selective filter which selectively transmits said first and second polarization light beams;
and
at least two photodiodes independently detecting said first and second polarization light beams transmitted through said electrically tunable liquid crystal wavelength-selective filter;
wherein said electrically tunable liquid crystal wavelength-selective filter includes
a first glass substrate;
a first transparent electrode layer;
a first highly reflective mirror;
a first alignment layer;
a liquid crystal layer;
a second alignment layer;
a transparent material layer whose refractive index is substantially equal to that of the liquid crystal of said liquid crystal layer;
a second highly reflective mirror;
and
a second transparent electrode layer;
which are arranged in this sequence,
wherein said first and second highly reflective mirrors define an etalon cavity having an optical length and said transparent material layer is present to increase the optical length of the etalon cavity, and
wherein said second electrically tunable liquid crystal wavelength-selective filter and said photodiodes are integrally arranged in such a manner that said photodiodes are arranged on said second transparent electrode layer.

18 more elements

A photodetector arrangement for receiving an optical signal via an input fiber, comprising:

polarization beam separation means for polarization separating light that has been received through said input fiber into a first beam and a second beam;
polarization rotation means for rotating the polarization of said second beam;
an electrically tunable liquid crystal wavelength-selective filter which selectively transmits the first and second beams, said filter including
a first transparent substrate;
a first transparent electrode layer on the first substrate;
a first mirror on the first electrode layer;
a second transparent substrate;
a second transparent electrode layer on the second substrate;
a second mirror on the second electrode layer, the second mirror being spaced apart from the first mirror;
a liquid crystal layer;
and
a transparent material layer made of a solid substance whose refractive index is substantially equal to that of the liquid crystal, the liquid crystal layer and the transparent material layer being disposed between the first and second mirrors;
and
at least one photodetector which receives light transmitted through the filter,
wherein the first and second mirrors define an etalon cavity having an optical length and the transparent material layer is present to increase the optical length of the etalon cavity.

12 more elements

Dependencies are inferred from the claim text.

Liquid crystal Fabry-Perot etalon with glass spacer

Life of this patent

Liquid crystal Fabry-Perot etalon with glass spacer

Life of this patent

Abstract

Claims44