Optical waveguides – Directional optical modulation within an optical waveguide – Light intensity dependent
Reexamination Certificate
2002-08-23
2004-09-14
Glick, Edward J. (Department: 2882)
Optical waveguides
Directional optical modulation within an optical waveguide
Light intensity dependent
C385S016000, C385S122000
Reexamination Certificate
active
06792167
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an optical switch and, more particularly, to an optical switch capable of operating at low power consumption, excellent in response speed, and having construction suitable for miniaturization and multichannelling.
An optical communication system capable of rapidly transmitting large-capacity information must be constructed for the further development of an information-oriented society. A wavelength division multiplexing system (WDM system) has been developed and the enhancement of transmission speed of networks has made a rapid progress.
A switching means for switching optical information is essential to achieving further rapid optical communication. A conventional optical information switching method needs light-to-electricity conversion means for converting optical information into corresponding electrical information and electricity-to-light conversion means for converting electrical information into corresponding electrical information at relay points. Total power consumption by the light-to-electricity conversion means and electricity-to-light conversion means increases and switching speed decreases with the increase of the number of relay points. Therefore, it is preferable that a rapid optical communication system employs optical switches capable of directly switching optical information.
Known optical switches including a mechanical optical switch, a plane optical waveguide optical switch, a mirror optical switch, and a bubble optical switch are mentioned in, for example, Nikkei Electronics, No. 8 (Jan. 29, 2000). Those conventional optical switches, however, need a switching time on the order of milliseconds and have difficulty in coping with future increases in capacity and communication speed of optical communication systems. The conventional optical switches require high electrical driving force for operation and consume much energy.
Japanese Patent Laid-open No. 11-337988 proposes an all-optical switch provided with nonlinear optical members and capable of quick response. This prior art optical switch has two nonlinear optical members and controls the two nonlinear optical members by two different optical control signals and hence this optical switch is large. Therefore, it is difficult to miniaturize a multichannel selector optical switch. Since the refractive index change ratio is small, power necessary for inducing a refractive index change on the order of 2% is in the high range of 5 to 50 MW/cm
2
and the power consumption of the optical switch is large.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an optical switch capable of operating at low power consumption and of being miniaturized, and having construction suitable for application to multichannelling.
According to a first aspect of the present invention, an optical switch includes at least one light-receiving core; a plurality of light-emitting cores which are used selectively for emitting the optical signal; and a plurality of waveguides connecting the light-receiving core and the plurality of light-emitting cores, wherein a nonlinear optical element which, when pumped, changes its refractive index by 2% or above relative to the surroundings to control a traveling direction of the optical signal is disposed near at least one of the plurality of waveguides.
According to a second aspect of the present invention, an optical switch includes: at least one light-receiving core for receiving an optical signal; a plurality of light-emitting cores which are used selectively for emitting the optical signal; and a plurality of waveguides connecting the light-receiving core and the plurality of light-emitting cores, wherein a nonlinear optical element which, when pumped, changes its refractive index by 2% or above relative to the surroundings to control the reflection of the optical signal is disposed on a wall of at least one of the plurality of waveguides.
According to a third aspect of the present invention, an optical switch includes at least one light-receiving core; a plurality of light-emitting cores which are used selectively for emitting an optical signal; and a plurality of waveguides connecting the light-receiving core and the plurality of light-emitting cores, wherein a nonlinear optical element which, when pumped, changes its refractive index by 2% or above relative to the surroundings to control the transmission/reflection of the optical signal is inserted in a hole formed in the waveguide.
According to a fourth aspect of the present invention, an optical switch includes at least one light-receiving core; a plurality of light-emitting cores which are used selectively for emitting an optical signal; and a plurality of waveguides connecting the light-receiving core and the plurality of light-emitting cores, wherein a nonlinear optical element which, when pumped, changes its refractive index by 2% or above relative to the surroundings to control the direction of the emitted optical signal is held between highly refractive substrates, an optical signal fallen on one of the highly refractive substrate is emitted through the other highly refractive substrate when the nonlinear optical element is not pumped, and an optical signal fallen on one of the highly refractive substrates is reflected by the same highly refractive substrate when the nonlinear optical element is pumped.
In any one of the foregoing optical switches, the nonlinear optical element and the substrate are stacked alternately to form an n×n matrix type optical switch.
The optical switch according to the present invention may further include a pumping light source that emits pumping light or a pumping power source that creates a pumping electric field for changing the refractive index of the nonlinear optical element.
The pumping light source or the pumping power source may have an output capacity of 1 MW/cm
2
or below.
Desirably, the refractive index of the nonlinear optical element has an extinction coefficient of 0.15% or below for a wavelength range of the optical signal.
The nonlinear optical element may have an energy gap corresponding to a wavelength in the range of 400 to 1200 nm.
The nonlinear optical element may be formed of a metal oxide selected from the group consisting of Co, Fe, Cr, Ni, V, Zn and Cu or a composite oxide containing the same metal oxide.
The nonlinear optical element may contain at least a metal selected from the group consisting of Co, Fe and Ni, and the metal is amorphous.
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patent: 6493478 (2002-12-01), DeRosa et al.
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patent: 5-216079 (1993-08-01), None
patent: 11-337988 (1999-12-01), None
patent: WO99/14764 (1999-03-01), None
patent: WO 04/27689 (2001-04-01), None
U.S. patent application Ser. No. 10/080,386, unavailable, filed unavailable.
Nikkei Electronics, Jan. 29, 2001, (No. 788), p. 163, Translation-in-Part.
Ando Masahiko
Honda Mitsutoshi
Naito Takashi
Sugita Tatsuya
Artman Thomas R
Glick Edward J.
Hitachi , Ltd.
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