摘要:
In a coherent optical receiver, sufficient demodulation becomes impossible and consequently receiving performance deteriorates if an interchannel skew arises, therefore, a coherent optical receiver according to an exemplary aspect of the invention includes a local light source; a 90-degree hybrid circuit; an optoelectronic converter; an analog-to-digital converter; and a digital signal processing unit, wherein the 90-degree hybrid circuit makes multiplexed signal light interfere with local light from the local light source, and outputs a plurality of optical signals separated into a plurality of signal components; the optoelectronic converter detects the optical signals and outputs detected electrical signals; the analog-to-digital converter quantizes the detected electrical signals and outputs quantized signals; and the digital signal processing unit includes a skew compensation unit for compensating a difference in propagation delay between the plurality of signal components, and a demodulation unit for demodulating the quantized signals.
摘要:
In a coherent optical receiver, sufficient demodulation becomes impossible and consequently receiving performance deteriorates if an inter-channel skew arises, therefore, a method for detecting inter-channel skew in a coherent optical receiver according to an exemplary aspect of the invention includes the steps of: outputting a plurality of optical signals separated into a plurality of signal components by making a test light from a test light source interfere with a local light from a local light source; detecting the optical signals and outputting detected electrical signals; quantizing the detected electrical signals and outputting quantized signals; performing a fast Fourier transform process on the quantized signals; and calculating a difference in propagation delay between the plurality of signal components on the basis of a plurality of peak values in the results of performing the fast Fourier transform process.
摘要:
In a coherent optical receiver, sufficient demodulation becomes impossible and consequently receiving performance deteriorates if an inter-channel skew arises, therefore, a coherent optical receiver according to an exemplary aspect of the invention includes a local light source, a 90° hybrid circuit, an optoelectronic converter, an analog to digital converter, and a digital signal processing unit; wherein the 90° hybrid circuit makes multiplexed signal light interfere with local light from the local light source, and outputs a plurality of optical signals separated into a plurality of signal components; the optoelectronic converter detects the optical signals and outputs detected electrical signals; the analog to digital converter quantizes the detected electrical signals and outputs quantized signals; the digital signal processing unit includes a skew compensation unit for compensating a difference in propagation delay between the plurality of signal components, and an FFT operation unit for performing a fast Fourier transform process on the quantized signals; and wherein the difference in propagation delay is calculated on the basis of a plurality of peak values with a central focus on one peak value in the results of performing the fast Fourier transform process.