Optical networks

An optical network element, comprising:

• an optical transmitter arranged to generate and transmit a first optical signal;
• a controller arranged to control said optical transmitter to generate and transmit said first optical signal at a wavelength selected from a predetermined plurality of wavelengths;
• and
• an optical receiver arranged to detect a second optical signal,
• wherein said controller is arranged to
• control said optical transmitter to generate and transmit said first optical signal in response said second optical signal not being detected,
• control said optical transmitter to iteratively generate and transmit said first optical signal at different wavelengths among said plurality of wavelengths while the optical receiver remains configured to detect the second optical signal at the same wavelength in each iteration, until said second optical signal is detected at the optical receiver with power greater than a threshold optical power, and
• in response to a determination that the second optical signal is received at the optical receiver with power greater than the threshold optical power, subsequently maintain generation and transmission of said first optical signal at said wavelength at which said second optical signal is detected.

A configuration method performed by an optical network unit (ONU) of an optical network, the ONU being optically connected to an optical line termination (OLT) over an optical link, the method comprising:

• transmitting, from the ONU, an uplink optical signal to the OLT, the uplink optical signal being an optical signal, and a wavelength of the uplink optical signal being selected from a plurality of wavelengths;
• subsequent to transmitting the uplink optical signal to the OLT, determining, at the ONU, whether a downlink optical signal is present on the optical link with power greater than a threshold optical power, the downlink optical signal being an optical signal transmitted from the OLT;
• and
• in response to determining that the downlink optical signal is present on the optical link with power greater than the threshold optical power, continuing to transmit, from the ONU, the uplink optical signal at the selected wavelength to the OLT;
• and
• in response to determining that the downlink optical signal is not present on the optical link with power greater than the threshold optical power, iterating through the step of transmitting the uplink optical signal to the OLT and the step of determining whether the downlink optical signal is present on the optical link with power greater than the threshold optical power until it is determined that that the downlink optical signal is present on the optical link with power greater than the threshold optical power,
• wherein in the step of transmitting the uplink optical signal to the OLT, a different wavelength among the plurality of wavelengths is selected in each iteration, and
• wherein in the step of determining whether the downlink optical signal is present on the optical link, sensing of the downlink optical signal is performed with respect to the same wavelength in each iteration.