Optical waveguides – With optical coupler – Switch
Reexamination Certificate
2001-03-05
2003-04-01
Ngo, Hung N. (Department: 2874)
Optical waveguides
With optical coupler
Switch
C385S014000
Reexamination Certificate
active
06542658
ABSTRACT:
BACKGROUND OF THE INVENTION AND THE RELATED ART
The present invention relates to an optical switch. More specifically, the present invention relates to an optical switch suitable for an optical communication system, an optical storage device, an optical arithmetic unit, an optical recorder, an optical printer and so forth, particularly, for the optical communication system in which a multichannel optical switch is desired to perform switching for each specific beam.
With recent developments in optical communication technology, optical switches have been sought that allow high-speed response, size reduction, high integration, low power consumption, and reduction of signal attenuation.
Conventionally-known optical switches include the ones in which liquid crystal is used, optical fibers are moved by a mechanical device using an electromagnet, a micromirror is used and so forth.
However, the optical switch using liquid crystal performs switching on the basis of molecular orientation, so that the optical switch has been slow in response and has not been easily adapted to optical communication requiring high-speed communication. There also has been a problem in that utilization efficiency of light is low since a polarizing plate has to be employed.
In the optical switch in which optical fibers are moved by a mechanical device using an electromagnet, the device could not be reduced in size and it has been difficult to meet the demands for a high degree of integration. Additionally, there has been a problem in that power consumption is large as switching is performed by the mechanical operations of an electromagnet.
In the optical switch using a micromirror, the manufacturing process becomes complex and the manufacturing costs are thus high, which is troublesome. There also has been a problem in that attenuation of signals is large since propagating light in the atmosphere is controlled.
In addition to these optical switches, an optical switch is proposed that performs switching by utilizing the change in refractive indexes of optical waveguides due to electro-optic effects during the application of electric fields to the optical waveguides.
However, in this type of optical switch, there is a problem in that the switch is likely to be affected by electric fields applied by other switches so that other optical waveguides are controlled. Particularly, when an optical switch is reduced in size, electrodes to apply electric fields to each optical waveguide inevitably get close to each other, increasing the effect of electric fields between adjacent optical waveguides and generating errors due to crosstalk and so forth, which has been troublesome.
On the other hand, an optical switching element is proposed that has: a light guide portion for performing light transmission by confining light internally by total reflection; an optical switching portion for extracting the light trapped internally to the outside of the light guide portion when the portion is in contact with the light guide portion, and then reflecting the extracted light into the direction of the light guide portion; and a driving portion for driving the optical switching portion (Japanese Unexamined Patent Application Publication No. 11-202222).
However, this optical switching element is configured to let the light guide portion extend light transmission of input light only in one direction. At the same time, the switching element unintentionally outputs the light that is input to the light guide portion, to the outside by contacting the switching portion to an unspecific total reflecting plane of the light guide portion. In other words, the switch only turns light on or off. Accordingly, the following configurations cannot be achieved: a switching element as an optical switch that outputs specific input light after switching the optical path thereof to a specific plurality of output side ends; an optical switch that outputs a specific plurality of input light to specific output ends by switching each optical path of the input light; and a multichannel optical switch that outputs a specific plurality of input light after switching the input light to a specific plurality of output ends. Although the switching element may be applicable to objects such as an image display, it has been practically difficult to apply the switching element to an optical communication system.
Moreover, in addition to the configuration whereby the light guide portion extends light transmission only in one direction, the optical switching element is configured to utilize infinitely repeated total reflection of the light guide portion. Thus, an emitting direction at the switching portion, in consideration of refraction at an interface between atmosphere and the light guide portion, is restricted to a deeper angle than the total reflection angle thereof; in other words, an almost vertical direction to the total reflecting plane. Even in this sense, switching to transmit light into different directions for each specific light could not be performed.
Therefore, the object of the present invention is to provide an optical switch suitable for an optical communication system, that solves the problems of conventional optical switches, and allows for low power consumption, a high-speed response, size reduction and high integration, significant reduction of signal attenuation and, furthermore, switching per specific input light.
SUMMARY OF THE INVENTION
The present inventors, after thorough researches to solve the above-noted problems, have discovered that the object mentioned above may be achieved by providing a light transmission portion having optical transmission channels, consisting of optical wave guiding bodies, in at least three directions with a light reflecting plane at one part on a surface of a light transmission portion, facing an optical path-changing portion, as a starting point. The optical path-changing portion is contacted or separated from the light reflecting plane of the light transmission portion at wavelength levels of input light based on displacement of an actuator portion.
Specifically, according to the present invention, there is provided an optical switch including at least a light transmission portion, an optical path-changing portion, and an actuator portion. The light transmission portion has a light reflecting plane provided at least at one part of a plane facing the optical path-changing portion to totally reflect light. Light transmission channels are provided, which consist of optical wave guiding bodies, in at least three directions with the light reflecting plane functioning as a starting point. The optical path-changing portion is provided in proximity to the light reflecting plane of the light transmission portion in a movable condition and has a light introduction member made of a translucent material and a light reflection member for totally reflecting light. The actuator portion has a mechanism that is displaced by external signals and transmits the displacement to the optical path-changing portion. The optical path-changing portion is contacted or separated from the light reflecting plane of the light transmission portion by displacement of the actuator portion in response to external signals. An optical path where the light input to the light transmission channel is totally reflected at the light reflecting plane of the light transmission portion and is transmitted to a specific light transmission channel on an output side, is switched to another optical path where the light input to the light transmission channel is taken to the light introduction member, and is totally reflected at the light reflection member and is transmitted to a specific light transmission channel on an output side.
It is preferable, in the present invention, that the actuator portion has a piezoelectric/electrostrictive element including a piezoelectric/electrostrictive layer and at least one pair of electrodes arranged on one part of the piezoelectric/electrostrictive layer. A vibrating member is provided and is in contact with at least one p
Kimura Koji
Nanataki Tsutomu
Takeuchi Yukihisa
Burr & Brown
NGK Insulators Ltd.
Ngo Hung N.
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