Method and apparatus for signal processing by light waveform shaping

Abstract

A method and apparatus for signal processing by light waveform shaping are provided to process an uplink signal generated by a digital-to-analog converter (DAC) and/or process a downlink signal to be transmitted to an analog-to-digital converter (ADC). The method includes adjusting the waveform of the uplink signal and/or the waveform of the downlink signal with a light waveform shaping module so that, even if the DAC and/or ADC has a low sampling rate and a narrow bandwidth, a high-frequency signal portion of the uplink signal and/or a high-frequency signal portion of the downlink signal can be preserved.

1 - 8 . (canceled) 
     
     
         9 . An apparatus for signal processing by light waveform shaping, comprising:
 a digital-to-analog converter generating an uplink signal;   an analog-to-digital converter receiving a downlink signal; and   a light waveform shaper separately and electrically connected to the digital-to-analog converter and the analog-to-digital converter and processing at least one of the uplink signal and the downlink signal, the light waveform shaper including an optical modulation subsystem and an optical gating, the optical modulation subsystem turning the uplink signal into a light pulse signal and thereby preventing suppression of a high-frequency image signal portion of the uplink signal, and the optical gating suppressing inter-sample interference of the downlink signal and thereby eliminating a low-pass effect in order to preserve aliasing between a high-frequency signal portion and a low-frequency signal portion of the downlink signal.   
     
     
         10 . The apparatus of  claim 9 , wherein each of the optical modulation subsystem and the optical gating includes at least one optical modulator, and the at least one optical modulator of the optical modulation subsystem or the optical gating is one or an arbitrary combination of an electro-absorption modulator, a Mach-Zehnder interferometer, a gain-switching (GS) pulse laser diode, and a semiconductor optical amplifier.