Abstract: An optical access network comprises L wavelength division multiplexed access sub-networks. Each of the wavelength division multiplexed access sub-networks is arranged to use a set of wavelength channels. M optical line termination apparatus, each receive traffic from a respective operator network and output traffic on the wavelength channels. A wavelength routing apparatus comprises M sets of first ports and L second ports. Each set of first ports connects to a respective one of the optical line termination apparatus and each second port connects to an optical link of a respective one of the wavelength division multiplexed access sub-networks. The wavelength routing apparatus is arranged to route the set of wavelength channels between the sets of first ports and the second ports and to route different wavelength channels of the same wavelength to different ones of the second ports.

Abstract: An optical network (1) comprising an optical network element (10) comprising a first optical transmitter (14), a first controller (16), a first optical receiver and a second optical receiver and a second optical network element (12). There is provided a transmission path (30) between said first optical network element and said second optical network element. Said first optical transmitter is arranged to generate and transmit a first optical signal. Said first controller is arranged to control said first optical transmitter to generate and transmit said first optical signal at a wavelength selected from a predetermined plurality of wavelengths. Said first optical receiver is arranged to detect a backscatter portion of said first optical signal returned to said first optical network element along said transmission path by distributing scattering.

Abstract: A method 10 of configuring a WDM PON comprising an OLT and a plurality of ONTs, comprising: a. identifying a plurality of OLT ports which do not have an assigned ONT assigned 12, selecting one port 12, and generating and transmitting a wavelength availability signal from the port indicative of an operating wavelength of each port 14; b. at each of a plurality of unassigned ONTs: i. receiving said availability signal and tuning a transmission wavelength of the ONT tunable filter until it transmits said signal 16; ii. generating a wavelength sequence of the operating wavelengths of the ports; iii. sequentially setting the transmission wavelength of the tunable filter at the wavelengths of the wavelength sequence 20, 28 and generating and transmitting a handshake signal at each wavelength 22 until the availability signal is no longer received 30; c. at the selected port, determining a number of handshake signals received at its operating wavelength 24.

Abstract: An optical network (10) comprising an optical network element (12) comprising a first optical transmitter (14), a first controller (16), an optical receiver (18), a second optical transmitter (22), a second controller (24) and optical receiver apparatus (26). Said first controller is arranged to control said first optical transmitter to generate and transmit a first optical signal in response no second optical signal being detected. Said first controller is arranged to iteratively generate and transmit said first optical signal at different wavelengths of a plurality of wavelengths until said second optical signal is detected, and is further arranged to subsequently maintain generation and transmission of said first optical signal at said wavelength at which said second optical signal is detected. Said second controller is arranged to control said second optical transmitter to generate and transmit said second optical signal following detection of said first optical signal by said optical receiver apparatus.

Abstract: An optical network (10) comprises a first optical transmitter (12), a first controller (14), optical receiver apparatus (16) and an optical network element (20) comprising an optical receiver (22), a second optical transmitter (24), and a second controller (26). The first controller controls the first optical transmitter to generate and transmit a first optical signal having a first signal format until the optical receiver apparatus detects the second optical signal and subsequently controls it to apply a second signal format to said first optical signal. The second controller (26) controls the second optical transmitter to iteratively generate and transmit the second optical signal at different wavelength until a first optical having a second signal format is detected. The second controller subsequently maintains generation and transmission of the second optical signal at the wavelength at which the first optical signal was identified as having the second signal format.

Abstract: A unit and a system for protection switching of line cards in a telecommunication system are described. A protection unit is connectable between communication lines and a line interface unit. The protection unit can be interconnected with other protection units to form a protection switching system. One protection unit in the protection switching system is connectable to a stand-by line card. The protection switching system is configured so that when protection switching is needed, the line signal is re-directed between the communication line for a failed line card and the stand-by line card via electrical connection elements.