Light beams or optical signals are frequently used to transmit digital data. For example, optical signals are used in fiber optic systems for long-distance telephony and Internet communication. Additionally, optical signals are frequently used to transmit data between electronic components on a single circuit board or between electronic components on adjacent or nearby circuit boards.
Systems utilizing optical communication often rely upon the precise manipulation of optical energy, usually in the form of a light beam, to accomplish a desired task. This is especially true in systems utilizing light for high-speed, low-energy communication between multiple nodes. In such systems, optical data signals typically travel through one or more waveguides which are connected to the various nodes.
To efficiently pass information through the system, it is often necessary to combine, separate, and route various optical signals. For example, it may be desirable to extract a specific optical signal from a first waveguide and selectively route it into any one of a number of other waveguides. This can be accomplished by converting the optical signal into an electrical signal, then using a laser or other optical source to reconstruct the optical signal in the desired waveguide. This technique has a key limitation: the electronic circuits limit the maximum bandwidth of the signal.
A second approach uses an optical switching device to transfer the optical signal from one waveguide to another waveguide. Optical switches may operate by mechanical means, such as physically shifting an optical fiber such that it drives one or more alternative fibers. A mechanical switch is relatively slow and can only shift the optical signal into a small number of alternative fibers. Optical switches may also use electro-optic effects, magneto-optic effects, or other methods. These optical switches can be much faster than mechanically actuated switches but are still limited in their ability to route optical signals to a large number of alternative waveguides without complex architectures and multiple switching elements. These complex architectures can be expensive to manufacture, fragile, and require a relatively large area within the photonic device.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.