Method of detecting one or more free channels in an optical time-division multiplex, a device for implementing it and the use of the device

A device for detecting and identifying one or more free channels in a time-division multiplexed optical signal, the device comprising:

• a coupler having one input and a plurality of outputs for dividing the time-division multiplexed optical signal into a plurality of optical signals corresponding to a plurality of channels forming the time-division multiplexed optical signal,
• a sampling circuit for sampling successive optical pulses of the optical signals output from the coupler clocked by clock signals corresponding to a baseband frequency of the time-division multiplexed optical signal and offset relative to each other by a time period corresponding to a width of a channel,
• a low-frequency detector circuit adapted to measure an average power of the optical pulses of each of the optical signals during a particular time period of each channel identified by the sampling circuit, and
• a signal generator circuit for generating a detection signal indicating detection of a free channel if the average power of the optical pulses of at least one of the optical signals is less than or equal to a particular threshold.

An insertion system for inserting encoded optical pulses into a time-division multiplexed optical signal, the insertion system comprising at least one insertion module comprising a detector device for detecting and identifying one or more free channels in a time-division multiplexed optical signal, the detector device comprising:

• a coupler having one input and a plurality of outputs for dividing the time-division multiplexed optical signal into a plurality of optical signals corresponding to a plurality of channels forming the time-division multiplexed optical signal,
• a sampling circuit for sampling successive optical pulses of the optical signals output from the coupler clocked by clock signals corresponding to a baseband frequency of the time-division multiplexed optical signal and offset relative to each other by a time period corresponding to a width of a channel,
• a low-frequency detector circuit adapted to measure an average power of the optical pulses of each of the optical signals during a particular time period of each channel identified by the sampling circuit, and
• a signal generator circuit for generating a detection signal indicating detection of a free channel if the average power of the optical pulses of at least one of the optical signals is less than or equal to a particular threshold.