Abstract
We demonstrate an optical quadrature phase-shift keying (QPSK) signal transmitter and an optical receiver for demodulating optical QPSK signal with homodyne detection and digital signal processing (DSP). DSP on the homodyne detection scheme is employed without locking the phase of the local oscillator (LO). In this paper, we present an extracting one-dimensional array of down-sampling method for reducing unwanted samples of constellation diagram measurement. Such a novel scheme embodies the following major advantages over the other conventional optical QPSK signal detection methods. First, this homodyne detection scheme does not need strict requirement on LO in comparison with linear optical sampling, such as having a flat spectral density and phase over the spectral support of the source under test. Second, the LabVIEW software is directly used for recovering the QPSK signal constellation without employing complex DSP circuit. Third, this scheme is applicable to multilevel modulation formats such as M-ary PSK and quadrature amplitude modulation (QAM) or higher speed signals by making minor changes.
Highlights
There has been a remarkable change in the area of high-speed optical fiber communications in recent years
In order to overcome the restriction on oversampling in the analog-to-digital convertors (ADCs) embedded within a LeCroy serial data analyzer (SDA; SDA 825Zi-A), we propose a novel extracting one-dimensional array of down-sampling method for reducing unwanted samples of constellation diagram measurement
We discover that there exist several over-sampled samples in the waveform diagram of the reconstructed quadrature phase-shift keying (QPSK) signal samples
Summary
There has been a remarkable change in the area of high-speed optical fiber communications in recent years. In order to overcome the restriction on oversampling in the ADCs embedded within a LeCroy serial data analyzer (SDA; SDA 825Zi-A), we propose a novel extracting one-dimensional array of down-sampling method for reducing unwanted samples of constellation diagram measurement. This enables us to monitor, simultaneously, the amplitude and phase modulations of ultrafast optical QPSK signals
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