Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
2001-11-15
2003-09-30
Pert, Evan (Department: 2829)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C385S014000, C250S515100
Reexamination Certificate
active
06628450
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to optical devices and, more specifically, the present invention relates to a phase-shifting device.
2. Background Information
The need for fast and efficient optical switches is increasing as Internet data traffic growth rate is overtaking voice traffic pushing the need for optical communications. Two commonly found types of optical devices are mechanical devices and electro-optic devices.
Mechanical devices such as switching devices generally involve physical components that are placed in the optical paths between optical fibers. These components are moved to cause switching action. Micro-electronic mechanical systems (MEMS) have recently been used for miniature mechanical switches. MEMS are popular because they are silicon based and are processed using somewhat conventional silicon processing technologies. However, since MEMS technology generally rely upon the actual mechanical movement of physical parts or components, MEMS are generally limited to slower speed optical applications, such as for example applications having response times on the order of milliseconds.
In known electro-optic devices such as switching devices, interferometers, phase-shifters, etc., voltages are continuously applied to selected parts of a device to create electric fields within the device. The electric fields change the optical properties of selected materials within the device and the electro-optic effect the optical beams. Electro-optic devices typically utilize electro-optical materials that combine optical transparency with voltage-variable optical behavior.
Although the speeds of some known electro-optic devices are very fast, for example on the order of nanoseconds, one disadvantage with known electro-optic devices is that these devices generally require relatively high voltages in order to operate. Consequently, the external circuits utilized to control known electro-optical devices are usually specially fabricated to generate the high voltages and suffer from large amounts of power consumption. In addition, integration of these external high voltage control circuits with present day electro-optical switches is becoming an increasingly challenging task as device dimensions continue to scale down and circuit densities continue to increase.
Another disadvantage with known electro-optic devices is that these devices generally require voltages to be continuously applied in order to operate. Consequently, power is continuously consumed in order to operate these devices. Moreover, these devices no longer function at all if there is a power failure. As a result, the integrity of for example an optical communications system using such a known electro-optic device is compromised in the event of such a power failure.
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