Wavelength division multiplexed optical communication system having variable channel spacings

摘要

Consistent with the present disclosure, data, in digital form, is received by a transmit nodes of an optical communication, and converted to analog signal by a digital-to-analog converter (DAC) to drive a modulator. The modulator, in turn, modulates light at one of a plurality of wavelengths in accordance with the received data. The modulated light is then transmitted over an optical communication path to a receive node. At the receive node, the modulated optical signal, as well as other modulated optical signals are supplied to a photodetector circuit, which receives additional light at one of the optical signal wavelengths from a local oscillator laser. An analog-to-digital converter (ADC) is provided in the receive node to convert the electrical signals output from the photodetector into digital form. The output from the ADC is then filtered in the electrical domain, such that optical demultiplexing of individual channels is unnecessary.

主权项

1. A system, comprising:
a first transmitter including:
a first digital signal processor circuit configured to receive input data, the digital signal processor being configured to sample the input data at a first sampling rate, and spectrally shape the input data to supply spectrally shaped data as a first plurality of data samples at the first sampling rate,a first interpolation circuit that receives the first plurality of data samples at the first sampling rate and outputs the spectrally shaped data as a second plurality of data samples at a second sampling rate greater than the first sampling rate,a digital-to-analog converter circuit configured to receive the second plurality of data samples and generate an analog signal,a modulator circuit, anda laser configured to supply light to the modulator circuit, the modulator circuit being configured to modulate the light to supply a first modulated optical signal in response to the analog signal, a second transmitter supplying a second modulated optical signal; a combiner configured to combine the first modulated optical signal with the second modulated optical signal onto an optical communication path; and a receiver coupled to the optical communication path, the receiver including:
a photodiode that receives portions the first and second modulated optical signals, the photodiode supplying an electrical output,a low-pass filter that supplies a filtered output in response to the electrical output,an analog-to-digital converter configured to sample the filtered output at the second sampling rate to generate a plurality of third data samples,a second interpolation circuit configured to receive the plurality of third data samples and supply a plurality of fourth data samples at a third sampling rate less than the second sampling rate, anda second digital signal processor circuit configured to receive the plurality of fourth data samples.