Abstract: A method for decoding a digital signal includes receiving a multiple-bit digital signal that includes information to be transmitted; arraying bit strings of the received multiple-bit digital signal to thereby generate a received signal image as a two-dimensional image; arraying all types of predetermined proper signals used for signals transmitted and bit strings of patterns including errors each derived from each proper signal to thereby generate a different two-dimensional image and disposing a set of received signal patterns, each comprised of an arbitrary proper signal and a group of two-dimensional images of patterns having the arbitrary proper signal added with an error, in a state that enables identification of each proper signal to thereby generate a received signal pattern image; using optical signal processing to evaluate a coefficient of correlation between the received signal image and the received signal pattern image to thereby obtain a correlation projection image in which depth and brightness

Abstract: A method for decoding a digital signal includes receiving a multiple-bit digital signal that includes information to be transmitted; arraying bit strings of the received multiple-bit digital signal to thereby generate a received signal image as a two-dimensional image; arraying all types of predetermined proper signals used for signals transmitted and bit strings of patterns including errors each derived from each proper signal to thereby generate a different two-dimensional image and disposing a set of received signal patterns, each comprised of an arbitrary proper signal and a group of two-dimensional images of patterns having the arbitrary proper signal added with an error, in a state that enables identification of each proper signal to thereby generate a received signal pattern image; using optical signal processing to evaluate a coefficient of correlation between the received signal image and the received signal pattern image to thereby obtain a correlation projection image in which depth and brightness

Abstract: A method and apparatus for generating optical pulses using an active mode-locking laser that includes a first modulation device, an optical selection device, a second modulation device and an amplification device. The method includes the steps of using the first modulation device to modulate a lightwave, selecting a modulation lightwave signal having a high frequency component by passing a lightwave through the optical selection device in a first direction, using the second modulation device to modulate a lightwave, selecting a modulation lightwave signal having a high frequency component by passing a lightwave through the optical selection device in a second direction, amplifying the lightwave selected by the above step, and supplying the amplified lightwave to the first modulation device.

Abstract: A method and apparatus for generating optical pulses using an active mode-locking laser that includes a first modulation device, an optical selection device, a second modulation device and an amplification device. The method includes the steps of using the first modulation device to modulate a lightwave, selecting a modulation lightwave signal having a high frequency component by passing a lightwave through the optical selection device in a first direction, using the second modulation device to modulate a lightwave, selecting a modulation lightwave signal having a high frequency component by passing a lightwave through the optical selection device in a second direction, amplifying the lightwave selected by the above step, and supplying the amplified lightwave to the first modulation device.