Optical switch and optical add/drop multiplexer

Abstract

To provide with a wavelength-selection optical switch able to select a light with a certain wavelength and an optical add/drop multiplexer using the same. An optical switch comprising: a silicon substrate; a glass substrate arranged to face a surface of the silicon substrate and having a transparent electrode layer in its opposing surface; a light diffraction reflection layer aligned on a surface of the silicon substrate; a liquid crystal layer aligned between the light diffraction reflection layer and the transparent electrode layer; a silicon substrate electrical terminal extracted from a rear surface of the silicon substrate; and a means for applying voltage between the transparent electrode layer and the silicon substrate electrical terminal; wherein selection of wavelength of light diffracted and reflected by the light diffraction reflection layer is possible by controlling the refraction index of the liquid crystal layer through the voltage. Wavelength multiplexed light signal is widened its beam diameter by a collimator lens, the wavelength multiplexed light signal with widened beam diameter is directed to the optical switch, a light signal which has wavelength selected through the applied voltage on the optical switch is only diffracted and reflected by the optical switch.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a longitudinal sectional view schematically showing a configuration of a variable wavelength optical filter 1 according to the present invention.

FIG. 1B (a) illustrates the corresponding top view, and FIG. 1B (b) illustrates the corresponding bottom view.

FIG. 2 illustrates a view for explaining operation principle of the variable wavelength optical filter 1 shown in FIG. 1A.

FIG. 3 illustrates a graph showing the relationship between the effective area width of the variable wavelength optical filter achievable reflectivity of more than or equal 98% and FWHM of the reflectivity.

FIG. 4 illustrates a view schematically showing an exemplified configuration of the optical switch, which is the variable wavelength optical filter shown in FIG. 1A, and the optical add/drop multiplexer using this.

FIG. 5 illustrates a view schematically showing another exemplified configuration of two optical switches which are the variable wavelength optical filters shown in FIG. 1A, and optical add/drop multiplexer using them.

FIG. 6 illustrates a view schematically showing yet another exemplified configuration of two optical switches which are the variable wavelength optical filters shown in FIG. 1A, and optical add/drop multiplexer using them.

FIGS. 7( a) and (b) illustrate views schematically showing an exemplified configuration of the variable optical attenuator (wavelength blocker) of the prior art, respectively.

FIG. 8 illustrates views schematically showing an configuration of a variable wavelength optical filter of the prior art: (a) a longitudinal sectional view, and (b) top view.

Claims

1. An optical switch comprising: a silicon substrate; a glass substrate arranged to face a surface of said silicon substrate and having a transparent electrode layer in its opposing surface; a light diffraction reflection layer aligned on a surface of said silicon substrate; a liquid crystal layer aligned between said light diffraction reflection layer and said transparent electrode layer; a silicon substrate electrical terminal extracted from a rear surface of said silicon substrate; and a means for applying voltage between said transparent electrode layer and said silicon substrate electrical terminal; wherein selection of wavelength of light diffracted and reflected by said light diffraction reflection layer is possible by controlling the refraction index of said liquid crystal layer through said voltage.

2. The optical switch of claim 1, wherein its height is less than or equal to 3 mm, and its width is less than or equal to 4.5 mm.

3. An optical add/drop multiplexer comprises: a collimator lens for widen a beam diameter of a wavelength multiplexed optical signal; and the optical switch of claim 1 or 2 for receiving said wavelength multiplexed optical signal with widened beam diameter; wherein only optical signal with wavelength selected depending on a voltage applied to said optical switch from said wavelength multiplexed optical signal is diffracted and reflected by said optical switch.

4. An optical add/drop multiplexer comprises: a first collimator lens for widening a beam diameter of a wavelength multiplexed optical signal; a second collimator lens for widening a beam diameter of an optical signal with a certain wavelength; and the optical switch of claim 1 or 2 for receiving said wavelength multiplexed optical signal with widened beam diameter and said optical signal with a certain wavelength; wherein said optical signal with the certain wavelength is diffracted and refracted by setting the voltage applied to said optical switch in order to select said certain wavelength, and said optical signal with the certain wavelength is joined to said wavelength multiplexed optical signal.

5. The optical add/drop multiplexer of claim 3 or 4; wherein said collimator lens widens the beam diameter to more than or equal to 1.3 mm.