Angular Momentum
Encoding Information with Light’s Orbital Angular Momentum
Light is the future of communication, traveling at 3,000,000 meters per second, the cosmic speed limit of the universe. Its tremendous speed makes it optimal for data transmission. The conventional method to encode information in light is through amplitude modulation, i.e. light pulses, time division multiplexing, i.e. delaying the time light beams enter a channel, and wavelength multiplexing, i.e. multiple beams of light in one channel. Regardless of the method, information is stored in binary code, strings of ones and zeroes. Optimally, the channel capacity for a signal A is x bits/s where x does not account for signal deterioration (Figure 1).
Figure : Data Transmission of a Signal, A. Wavelength division multiplexing (WDM), storing light beams of different wavelengths in one channel is an efficient method of storing and sending information. Different sources of light are coupled together with a multiplexer, a device that combines them into one beam of light. The beam travels through a transfer medium. The demultiplexer, usually the mirror image of the multiplexer, separates into the respective wavelengths that comprise it. In a way, multiplexing performs a function f(x) on the different beams of light and the demultiplexer performs the inverse of that function f’(x). Figure : WDM Schematic Figure : Expected Trends for Channel Capacity
However, WDM is no longer efficient in meeting the increasing demand for more bandwidth, the information capacity of a channel. WDM is also not likely to meet the demand because of its intrinsic nature to overlap channels. If we take Input A and combine it with Input B, the input A+B will not stay distinct. They will merge into Input C. We may not find a workaround. DiGiovanni illustrates in Evolution of Optical Transmission: Impending Crunch (Figure 3) that the WDM technique has reached its full potential at a channel capacity, the amount of information a
Light is the future of communication, traveling at 3,000,000 meters per second, the cosmic speed limit of the universe. Its tremendous speed makes it optimal for data transmission. The conventional method to encode information in light is through amplitude modulation, i.e. light pulses, time division multiplexing, i.e. delaying the time light beams enter a channel, and wavelength multiplexing, i.e. multiple beams of light in one channel. Regardless of the method, information is stored in binary code, strings of ones and zeroes. Optimally, the channel capacity for a signal A is x bits/s where x does not account for signal deterioration (Figure 1).
Figure : Data Transmission of a Signal, A. Wavelength division multiplexing (WDM), storing light beams of different wavelengths in one channel is an efficient method of storing and sending information. Different sources of light are coupled together with a multiplexer, a device that combines them into one beam of light. The beam travels through a transfer medium. The demultiplexer, usually the mirror image of the multiplexer, separates into the respective wavelengths that comprise it. In a way, multiplexing performs a function f(x) on the different beams of light and the demultiplexer performs the inverse of that function f’(x). Figure : WDM Schematic Figure : Expected Trends for Channel Capacity
However, WDM is no longer efficient in meeting the increasing demand for more bandwidth, the information capacity of a channel. WDM is also not likely to meet the demand because of its intrinsic nature to overlap channels. If we take Input A and combine it with Input B, the input A+B will not stay distinct. They will merge into Input C. We may not find a workaround. DiGiovanni illustrates in Evolution of Optical Transmission: Impending Crunch (Figure 3) that the WDM technique has reached its full potential at a channel capacity, the amount of information a