Optical transmission between a central terminal and a plurality of client terminals via an optical network

1. A method of optical transmission between a central terminal and a plurality of client terminals via an optical network, said method being characterized in that it comprises a downlink transmission stage for transmitting downlink data (D 1 , D 2 ) and an uplink transmission stage for transmitting uplink data (D′ 1 , D′ 2 ),

said downlink transmission stage comprising the steps of:

said central terminal transmitting a downlink optical signal (S) which is multiplexed in both amplitude and time, at a single wavelength (λ 0 ), and carrying the downlink data (D 1 , D 2 ) to be received by said plurality of client terminals, said downlink optical signal (S) at a single wavelength (λ 0 ) consisting of soliton pulses having a plurality of amplitudes (A 1 , A 2 );

using a non-linear soliton trapping effect to convert said single wavelength (λ 0 ) of said downlink optical signal (S) into a plurality of wavelengths (λ 1 , λ 2 ) as a function of said plurality of amplitudes (A 1 , A 2 ) to form a wavelength division multiplexed downlink optical signal (S f );

said central terminal routing the wavelength division multiplexed downlink optical signal (S f ) to said plurality of client terminals; and

wavelength division demultiplexing said wavelength division multiplexed downlink optical signal (S f ) so that each client terminal receives the data (D 1 , D 2 ) intended for it at a specific wavelength (λ 1 , λ 2 ).

2. The method of optical transmission according to claim 1 , wherein said uplink transmission stage comprises the steps of:

transmitting a plurality of uplink optical signals (S′ 1 , S′ 2 ) to said central terminal, each uplink optical signal carrying the respective uplink data (D′ 1 , D′ 2 ) at a different wavelength (λ′ 1 , λ′ 2 ) and being transmitted by a respective client terminal from said plurality of client terminals with a specific amplitude (A′ 1 , A′ 2 ) and a predetermined time shift (t′ 1 , t′ 2 );

wavelength division multiplexing said plurality of uplink optical signals (S′ 1 , S′ 2 ) to form a wavelength division multiplexed uplink optical signal (S′ f ); and

routing said wavelength division multiplexed uplink optical signal (S′ f ) to one or more receivers for receiving the data (D′ 1 , D′ 2 ) transmitted by each client terminal of said plurality of client terminals.

3. The optical transmission method according to claim 1 further comprising a step of temporal compression of said soliton pulses before said conversion step.

4. The optical transmission method according to claim 2 , wherein said uplink transmission stage further comprises:

a wavelength division demultiplexing step in which the wavelength division multiplexed uplink optical signal (S′ f ) is spectrally demultiplexed into a plurality of spectral components; and

a step of reception of the uplink data by a plurality of receivers during which each of said spectral components carrying uplink data transmitted by a client terminal on a respective wavelength is received by a receiver from said plurality of receivers.

5. The optical transmission method according to claim 2 , wherein said uplink transmission stage further comprises:

a conversion step during which said wavelength division multiplexed uplink optical signal (S′ f ) is converted by a non-linear soliton trapping effect into a time division multiplexed uplink signal at a single wavelength (λ′ 0 ) carrying the uplink data; and

a step of a single receiver receiving the uplink signal at a single wavelength (λ′ 0 ).

6. The optical transmission system linking a central terminal and a plurality of client terminals via an optical network, said central terminal being adapted to transmit downlink data (D 1 , D 2 ) on a downlink to said plurality of client terminals and to receive uplink data (D′ 1 , D′ 2 ) on an uplink from said plurality of client terminals, wherein said system comprises on the downlink:

means for transmitting a downlink optical signal (S) at a single wavelength (λ 0 ) and carrying said downlink data (D 1 , D 2 ), said downlink optical signal (S) being multiplexed in both amplitude and time and consisting of soliton pulses having a plurality of amplitudes (A 1 , A 2 );

nonlinear means for converting by a soliton trapping effect said single wavelength (λ 0 ) of said downlink optical signal (S) into a plurality of wavelengths (λ 1 , λ 2 ) as a function of said plurality of amplitudes (A 1 , A 2 ) to form a wavelength division multiplexed downlink optical signal (S f );

routing means for routing the wavelength division multiplexed downlink optical signal (S f ) to said plurality of client terminals; and

first demultiplexing means for spectrally demultiplexing said downlink optical signal (S f ) so that each client terminal receives the downlink data (D 1 , D 2 ) for it on a specific wavelength (λ 1 , λ 2 ).

7. The system of optical transmission according to claim 6 , further comprising on the uplink:

means for transmitting a plurality of uplink optical signals (S′ 1 , S′ 2 ) to said central terminal, each uplink optical signal carrying the respective uplink data (D′ 1 , D′ 2 ) at a different wavelength (λ′ 1 , λ′ 2 ) and being respectively transmitted by a client terminal of said plurality of client terminals with a specific amplitude (A′ 1 , A′ 2 ) and with a predetermined time shift (t′ 1 , t′ 2 );

multiplexing means for wavelength division multiplexing said plurality of uplink optical signals (S′ 1 , S′ 2 ) to form a wavelength division multiplexed uplink optical signal (S′ f );

means for routing said wavelength division multiplexed uplink optical signal (S′ f ); and

one or more receivers for receiving the data (D′ 1 , D′ 2 ) transmitted by each client terminal of said plurality of client terminals.

8. The system according to claim 7 , further comprising on the uplink:

second demultiplexing means for spectrally demultiplexing the wavelength division multiplexed uplink optical signal (S′ f ) into a plurality of spectral components; and

a plurality of receivers at the output of said second demultiplexing means each adapted to receive uplink data carried by each spectral component and transmitted by a client terminal on a respective wavelength.

9. The system according to claim 7 , further comprising on the uplink:

non-linear means for converting by a soliton trapping effect the wavelength division multiplexed uplink optical signal (S′ f ) into a time division multiplexed uplink signal at a single wavelength (λ′ 0 ) carrying the uplink data; and

means for receiving said uplink signal at a single wavelength (λ′ 0 ).

10. The system according to claim 7 , further comprising temporal compression means upstream of said non-linear means for compressing said soliton pulses.

11. The system according to claim 6 , wherein said optical network is an access passive optical network.

12. An optical transmission central terminal comprising:

a transmitter for transmitting downlink data (D 1 , D 2 ) to a plurality of client terminals, said downlink data being carried by a downlink optical signal (S) at a single wavelength (λ 0 ) comprising a plurality of soliton pulses, said downlink optical signal (S) being multiplexed in both amplitude and time and having a plurality of amplitudes (A 1 , A 2 );

one or more receivers for receiving uplink data (D′ 1 , D′ 2 ) transmitted by said plurality of client terminals;

said central terminal being characterized in that it further comprises:

routing means for routing downlink and uplink data; and

a first optical converter between the transmitter and the routing means, said first optical converter comprising non-linear means for converting by a soliton trapping effect a single wavelength (λ 0 ) of said downlink optical signal (S) into a plurality of wavelengths (λ 1 , λ 2 ) as a function of said plurality of amplitudes (A 1 , A 2 ) so as to form a wavelength division multiplexed downlink optical signal (S f ).

13. The terminal according to claim 12 , comprising a receive demultiplexer and a plurality of receivers for receiving the uplink data (D′ 1 , D′ 2 ), each of said receivers being connected to said receive demultiplexer, and said routing means are disposed between said first non-linear means and said receive demultiplexer.

14. The terminal according to claim 12 , further comprising a data receiver and a second optical converter located between said routing means and said data receiver and comprising non-linear means.