Device and method for transmitting optical data signals
Disclosed are a device and a method for transmitting an optical data signal over an optical transmission channel, comprising a differential phase shift keying unit for differential phase shift keying of at least one serial data stream to generate a differential phase shift keying coded data stream; an amplitude shift keying unit for amplitude coding of at least two further serial data streams that can be selectively activated to generate an amplitude shift keying coded data stream; and a modulation unit for generating an optical data signal in accordance with a control signal that is, formed from the generated differential phase shift keying coded data stream and from the generated amplitude shift keying coded data stream.
1. A device for transmitting an optical data signal over an optical transmission channel, the device comprising:
(a) a differential phase shift keying unit for differential phase shift key coding of at least one serial data stream to generate a differential phase shift keying coded data stream;
(b) an amplitude shift keying unit for amplitude shift key coding of at least two further serial data streams that can be selectively activated with controllable switches to generate an amplitude shift keying coded data stream, wherein the switches are controlled in accordance with an operation mode control signal;
(c) a modulation unit for generating an optical data signal in accordance with a control signal that is formed from the generated differential phase shift keying coded data stream and from the generated amplitude shift keying coded data stream.
2. The device according to claim 1 , wherein the modulation unit is a Mach-Zehnder modulator.
3. The device according to claim 1 , wherein a multiplication unit forms the control signal for the modulation unit by multiplication of the differential phase shift keying coded data stream with the amplitude shift keying coded data stream.
4. The device according to claim 1 , wherein a demultiplexer partitions a serial data stream having a high data transmission rate into a plurality of serial data streams having a reduced data transmission rate.
5. The device according to claim 4 , wherein two of the serial data streams having a reduced data transmission rate are output by the demultiplexer to the differential phase shift keying unit).
6. The device according to claim 5 , wherein the other serial data streams having a reduced data transmission rate are output by the demultiplexer to the amplitude shift keying unit.
7. The device according to claim 6 , wherein the serial data streams having a reduced transmission rate that are output to the amplitude shift keying unit can be respectively selectively activated by the controllable switches.
8. The device according to claim 1 , wherein the differential phase shift keying unit comprises:
a multiplexer that switches alternatingly between two serial data streams and outputs a data stream at an output port of the multiplexer;
an XOR gate arranged downstream from the multiplexer, the XOR gate having a first input port that is connected to the output port of the multiplexer and a second input port that is connected via a delay element to an output port of the XOR gate.
9. The device according to claim 1 , wherein the differential phase shift keying unit comprises a first XOR gate receiving a serial data stream at a first input port and receiving at a second input port an output signal that is fed back from an output port of a second XOR gate via a delay element, and a multiplexer arranged downstream of the XOR gates that switches alternatingly between the output ports of the two XOR gates.
10. The device according to claim 9 , wherein the delay time of the delay element is inversely proportional to the data rate of the serial data stream at the input ports of the XOR gate.
11. The device according to claim 1 , wherein the amplitude shift keying unit comprises:
(a) a storage for storing a coding table that can be read out, in which a bit combination of amplitude bits is stored for any bit combination of the serial data streams input into the amplitude shift keying unit;
(b) a multiplexer for multiplexing the amplitude bits that are read out from the storage;
(c) amplifiers with adjustable amplification factors for amplifying the multiplexed amplitude bits; and
(d) an adder that adds amplified amplitude bits output by the amplifiers to generate the amplitude shift keying coded data stream.
12. The device according to claim 11 , wherein amplification factors of the amplifiers in the amplitude shift keying unit are adjusted by a controller in accordance with a detected error rate that occurs when transmitting the optical data signal over the optical transmission channel to a receiver.
13. The device according to claim 12 , wherein the detected error rate is transmitted from the receiver over a communication channel to the controller.
14. The device according to claim 4 , wherein the serial data stream having a high data transmission rate has a data transmission rate of 100 Gbaud.
15. The device according to claim 4 , wherein the serial data streams having a reduced data transmission rate each have a data transmission rate of 20 Gbaud.
16. The device according to claim 1 , wherein the generated differential phase shift keying coded data stream and the generated amplitude shift keying coded data stream each have a data transmission rate of 40 Gbaud.