Even with the low laser peak power transmitted by the SLM, only about 7 mW, the time needed to store a single image was less than 75 microseconds. Data thus stored can be retrieved only if the exact write pulse modulation code is known. One important feature associated with this approach is that the length of the code can be arbitrary, permitting the storage of ultra-wide bandwidth data with the modest laser power available with commercial lasers. Another example is analysis and recognition of optical data streams by spectral holography. In this scheme, the incoming signal is rapidly analyzed by performing simultaneous correlation operations with many reference signals stored in advance through angular multiplexing.
Recognition is accomplished by identifying the direction that yields the maximum correlation signal.
M.K. Kim and R. Kachru, J. Opt. M.K. Kim and R. Kachru, Opt. X.A. Shen and R. Kachru, Opt. R. Kachru, Y.S. Bai, and Y.A. Shen, Adv. X.A. Shen, E. Chiang, and R. Kachru, Opt.