Optical quantizing unit and optical A/D converter

Abstract

An optical quantizing unit includes an optical divider dividing 1 st optical pulses to be quantized and sending the divided 1 st optical pulses into a plurality of paths; a plurality of optical filters passing with different transmittances the divided 1 st optical pulses; and an optical threshold filter sequentially receiving the 1 st optical pulses, and sending 2 nd optical pulses when light intensities of the 1 st optical pulses are above a preset threshold value.

1 .- 10 . (canceled) 
   
   
       11 . A method for quantizing optical pulses, comprising:
 dividing first optical pulses to be quantized, in accordance with a number of quantizing levels;   sending each of the divided first optical pulses to each of a plurality of delay lines, so as to delay the divided first optical pulses in the delay lines by different delay times;   transmitting each of the divided first optical pulses, which have been delayed in the delay lines, to each of a plurality of optical filters passing the divided first optical pulses with different transmittances;   synthesizing each of the divided first optical pulses which have passed through the respective optical filters; and   transmitting a string of quantized second optical pulses when light intensities of the first optical pulses are above a preset threshold value.   
   
   
       12 . The method of  claim 11 , wherein the second optical pulses are transmitted by an optical threshold filter including laser oscillators. 
   
   
       13 . The method of  claim 11 , wherein each of the second optical pulses is transmitted by an optical threshold filter including a first laser oscillator whose laser output is reduced in response to the first optical pulses which arrive from the optical filters, and a second laser oscillator which receives the laser output from the first laser oscillator, and starts oscillation in response to the reduction of the laser output from the first laser oscillator, the optical threshold filter transmitting a laser output from the second laser oscillator. 
   
   
       14 . The method of  claim 13 , wherein the first and second laser oscillators respectively include semiconductor optical amplifiers. 
   
   
       15 . The method of  claim 11 , wherein the second optical pulses are transmitted by an optical threshold filter including a bistable semiconductor laser having a saturable absorber. 
   
   
       16 . The method of  claim 11 , wherein the second optical pulses are transmitted by an optical threshold filter including a resonator constituted by a nonlinear media sandwiched by multilayer mirrors.