Abstract: Optical transmitter/receivers for use in a DWDM systems are provided. Transmission of data signals in a quadrature-return-to-zero (QRZ) format achieves a data transmission rate equal to eight times a base data rate, i.e., 80 Gbps over a 100 GHz channel if the base data rate is 10 Gbps, with high non-linear performance by setting the polarization state of the data bands such that non-linear effects induced by PMD are reduced. Additionally, a transmitter achieves a transmission data rate equal to 16 times the base data rate by sharpening the QRZ pulses and interleaving pulse-sharpened QRZ data signals in the time domain, further doubling the data rate. Using counterpropagation in the transmitter, carrier signals and data signals traverse the same length of fiber, reducing fringing effects in the transmitter. Related techniques enhance reception and detection of data at high data rates. A local pulse-sharpened carrier is mixed with a QRZ data signal at a detector reducing amplification noise by a factor of two.

Abstract: An optical homodyne communication system and method in which a side carrier is transmitted along with data bands in an optical data signal, and upon reception, the side carrier is boosted, shifted to the center of the data bands, and its polarization state is matched to the polarization state of the respective data bands to compensate for polarization mode dispersion during transmission. By shifting a boosted side carrier to the center of the data bands, and by simultaneously compensating for the effects of polarization mode dispersion, the provided system and method simulate the advantages of homodyne reception using a local oscillator. The deleterious effects of chromatic dispersion on the data signals within the data bands are also compensated for by applying a corrective function to the data signals which precisely counteracts the effects of chromatic dispersion.

Abstract: A system and method for enhancing data capacity in optical data communication are described. First data is modulated onto a first optical carrier to occupy a data frequency range. The first optical carrier includes a first side frequency separated from the frequency range of the data band. A first modulated carrier having a first polarization state is output. Second data is modulated onto a second optical carrier signal occupying the same data frequency range. The second optical carrier includes a second side frequency separated from the data frequency range of the data band in a direction opposite from the first side frequency. A second modulated carrier having a first polarization state is output. The polarization state of the second modulated carrier is changed to a second polarization state orthogonal to the first polarization state and the first modulated carrier is combined with the second modulated carrier into a combined carrier.

Abstract: Information is optically transferred by generating an optical carrier signal having a first polarization state, generating an optical data signal separate from the optical carrier signal and having a second polarization state, matching the first polarization state and the second polarization state, combining the optical carrier signal with the optical data signal to create a combined optical signal, transferring the combined optical signal over an optical wave guide, and receiving the combined optical signal from the optical wave guide.