Polarization-switched differential ternary phase-shift keying

1. A method for transmitting ternary phase-shift keyed data, the method comprising:

mapping triplets of binary bits to pairs of ternary symbols, such that three bits of data are encoded across two symbols having three-point constellations;

modulating the pairs of ternary symbols onto a carrier;

transmitting the modulated carrier across a transmission medium; and

forming an alternating polarization optical carrier beam,

wherein said forming comprises:

modulating a series of pulses onto a laser beam;

removing every second pulse from the modulated beam;

splitting each pulses into two;

delaying one split pulse by one signal period;

rotating one split pulse's polarization; and

combining the split pulses to form a series of pulses having alternating polarization.

2. The method of claim 1 , further comprising chirping the pulses.

3. The method of claim 1 , further comprising encoding a binary bitstream according to a rate 8/9 code before performing said mapping.

4. A method for transmitting ternary phase-shift keyed data, the method comprising:

mapping triplets of binary bits to pairs of ternary symbols, such that three bits of data are encoded across two symbols having three-point constellations;

modulating the pairs of ternary symbols onto a carrier;

transmitting the modulated carrier across a transmission medium,

wherein modulating further comprises forming a ternary constellation by amplitude modulating two signal paths and phase modulating one of said signal paths, such that the two paths combine to form a four-point constellation having three points at a same amplitude that are centered at the origin and having one unused point at a higher amplitude than the other points.

5. A transmitter comprising:

an encoder configured to map triplets of binary bits to pairs of ternary symbols, such that three bits of data are encoded across two symbols having three-point constellations;

a modulator configured to modulate the pairs of ternary symbols onto a carrier for transmission across a transmission medium; and

a polarization switched pulse generator configured to form an alternating polarization optical carrier beam,

wherein said polarization switched pulse generator comprises:

a first amplitude modulator configured to modulate a series of pulses onto a laser beam;

a second amplitude modulator configured to remove every second pulse from the modulated beam;

a beam splitter configured to split each pulse into two pulse;

a delay module configured to delay one split pulse by one signal period;

a polarization rotator configured to rotate one split pulse's polarization; and

a beam combiner configured to combine the split pulses to form a series of pulses having alternating polarization.

6. The transmitter of claim 5 , further comprising a chirping module configured to chirp the pulses.

7. The transmitter of claim 5 , wherein the encoder is further configured to encode a binary bitstream according to a rate 8/9 code before performing said mapping.

8. A transmitter comprising:

an encoder configured to map triplets of binary bits to pairs of ternary symbols, such that three bits of data are encoded across two symbols having three-point constellations; and

a modulator configured to modulate the pairs of ternary symbols onto a carrier for transmission across a transmission medium,

wherein the modulator comprises two signal paths configured to form a ternary constellation, wherein each signal path comprises an amplitude modulator and one signal path comprises a phase modulator, such that the two paths combine to form a four-point constellation having three points at a same amplitude that are centered at the origin and having one unused point at a higher amplitude than the other points.