Inverse distortion is used to create an undistorted image from a distorted image. For each pixel in the undistorted
image it is required to determine which pixel in the distorted image should be used. However the process of
characterizing a lens using a model such as that of Brown, yields a non-invertible mapping from the distorted
domain to the undistorted domain. There are three current approaches to solving this: an approximation of the
inverse distortion is derived from a low-order version of Brown's model; an initial guess for the distorted position is
iteratively refined until it yields the desired undistorted pixel position; or a look-up table is generated to store the
mapping. Each approach requires one to sacrifice either accuracy, memory usage or processing time. This paper
shows that it is possible to have real-time, low memory, accurate inverse distortion correction. A novel method
based on the re-use of left-over distortion characterization data is combined with modern numerical optimization
techniques to fit a high-order version of Brown's model to characterize the inverse distortion. Experimental
results show that, for thirty-two 5mm lenses exhibiting extreme barrel distortion, inverse distortion can be
improved 25 fold to 0.013 pixels RMS over the image.
We experimentally demonstrate a novel decimal optical buffer scheme based on a multiloop configuration and a single switch element—an optical crosspoint switch (OXS) matrix. Its variable-delay range is of 1 to 999 times the basic delay unit. The buffer dynamic reconfiguration can be achieved at nanosecond switching speed. Our results show that by using a differential phase-shift keying (DPSK) payload in the buffer it can outperform an on-off keying payload with 4-dB sensitivity improvement owing to its alleviation of patterning-induced degradation, clearly validating DPSK as a promising modulation format to overcome nonlinear impairments and to extend number of hops in all-optical packet-switching network.
We experimentally demonstrate a novel decimal optical buffer scheme based on multi-loop configuration and single
switch element--an optical crosspoint switch (OXS) matrix. Our results show that by using a differential phase-shift
keying (DPSK) payload in the buffer can outperform OOK payload with 3.2 dB sensitivity improvement owing to its
alleviation of patterning induced degradation compared to OOK payload, clearly validating DPSK as a promising
modulation format to overcome nonlinear impairments and to extend number of hops in all-optical packet switching
We discuss how all-optical signal processing might play a role in future all-optical packet switched networks. We introduce a concept of optical packet switches that employ entirely all-optical signal processing technology. The optical packet switch is made out of three functional blocks: the optical header processing block, the optical memory block and the wavelength conversion block. The operation principle of the optical packet switch is explained. We show that these three functional blocks can be realized by using the nonlinearities of semiconductor optical amplifiers. Some technologies in these three functional blocks are described. The header processor is realized using a Terahertz Optical Asymmetric Demultiplexer. We also describe a header pre-processor to improve the extinction ratio of the header processor output. In the optical memory block, we show that an all-optical memory can be obtained by using two coupled lasers that form a master-slave configuration. The state of the optical memory is distinguished by the wavelength of the master laser. We extend the concept to an optical memory can have multiple states. In the wavelength conversion block, we demonstrate a 160 Gbit/s wavelength conversion using a single semiconductor optical amplifier in combination with a well-designed optical bandpass filter. The semiconductor optical amplifier has a gain recovery time
greater than 90 ps, which corresponds to a less than 20 GHz bandwidth for conventional wavelength conversion. We show that by properly using the optical bandpass filter, ultrafast dynamics in the semiconductor optical amplifier can be employed for wavelength conversion at ultrahigh bit-rates.
We discuss how all-optical signal processing might play a role in future all-optical packet switched networks. We describe a few approaches to optical header processing, all based on nonlinearities in a semiconductor optical amplifier. In first approach a SLALOM configuration is used. The second approach uses a Terahertz Optical Asymmetric Demultiplexer. We also describe a header pre-processor to improve the extinction ratio of the header processor output. The second functional block on which we focus is optical buffering. We show how all-optical signal processing technology can be used to route a packet into a fiber delay line and we describe a circulating optical loop based op optical technology.