An injection locked transmitter for an optical communication network includes a master seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one slave laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the master seed laser source. The laser injected modulator is configured to receive the master seed laser source input and the input data stream, and output a laser modulated data stream.

An injection locked transmitter for an optical communication network includes a master seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one slave laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the master seed laser source. The laser injected modulator is configured to receive the master seed laser source input and the input data stream, and output a laser modulated data stream.

A polarization-multiplexed self-homodyne analog coherent (PM-SH-ACD) architecture for optical communication links has a receiver section that polarization un-rotates a signal from a fiber optic cable into first and second polarized optical signals; recovers a polarization of the first and second optical signals based on a received polarization recovery signal that is based on a pilot signal measurement signal; demodulates the first optical signal into optical QPSK data and pilot tone signals; demodulates the second optical signal into an optical modulating laser light; splits the first and second optical signals into optical QPSK quadrature signals; converts the optical QPSK quadrature signals into electrical QPSK quadrature signals; detects a polarization of the pilot tone signal and outputs the pilot signal measurement signal polarization recovery signal based on the detected polarization.

A polarization-multiplexed self-homodyne analog coherent (PM-SH-ACD) architecture for optical communication links has a receiver section that polarization un-rotates a signal from a fiber optic cable into first and second polarized optical signals; recovers a polarization of the first and second optical signals based on a received polarization recovery signal that is based on a pilot signal measurement signal; demodulates the first optical signal into optical QPSK data and pilot tone signals; demodulates the second optical signal into an optical modulating laser light; splits the first and second optical signals into optical QPSK quadrature signals; converts the optical QPSK quadrature signals into electrical QPSK quadrature signals; detects a polarization of the pilot tone signal and outputs the pilot signal measurement signal polarization recovery signal based on the detected polarization.

The purpose of the present invention is to provide a device for optical frequency domain reflectometry and a method thereof that can measure a reflectance distribution with less spatial resolution degradation due to a phase noise, without using a wideband receiving system even when a long-distance measurement is performed. The device for optical frequency domain reflectometry according to the present invention is provided with a delay optical fiber for delaying a local light by a prescribed time, and obtains information on a relative delay of a backscattered light from an optical fiber under measurement with respect to the local light and information on the positivity and the negativity of a beat frequency by measuring an in-phase component and a quadrature component of a beat signal obtained by multiplexing the backscattered light from the optical fiber under measurement and the local light delayed by the delay optical fiber, so as to obtain a reflectance distribution in a longitudinal direction of the optical fiber under measurement based on these pieces of information.

An injection locked transmitter for an optical communication network includes a primary seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one secondary laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the primary seed laser source. The laser injected modulator is configured to receive the primary seed laser source input and the input data stream, and output a laser modulated data stream.

An injection locked transmitter for an optical communication network includes a primary seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one secondary laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the primary seed laser source. The laser injected modulator is configured to receive the primary seed laser source input and the input data stream, and output a laser modulated data stream.

Methods, systems, and devices for network communications to reduce optical beat interference (OBI) in upstream communications are described. For example, a fiber node may provide a narrow band seed source to injection lock upstream laser diodes. Therefore, upstream communications from each injection locked laser diode may primarily include the wavelength associated with each seed source. The seed sources may be unique to each end device and configured to minimize OBI. That is, the upstream laser diodes may be generic, but the received seed source may enable upstream communications at varying wavelengths. The fiber node may provide each seed source by filtering (e.g., by a grating filter) a broadband light source.

Methods, systems, and devices for network communications to reduce optical beat interference (OBI) in upstream communications are described. For example, a fiber node may provide a narrow band seed source to injection lock upstream laser diodes. Therefore, upstream communications from each injection locked laser diode may primarily include the wavelength associated with each seed source. The seed sources may be unique to each end device and configured to minimize OBI. That is, the upstream laser diodes may be generic, but the received seed source may enable upstream communications at varying wavelengths. The fiber node may provide each seed source by filtering (e.g., by a grating filter) a broadband light source.

One example optical transceiver includes an optical interface, an optical receiver, and a polarization-maintaining optical waveguide, where the optical receiver includes a mixer, an optical-to-electrical converter, an analog-to-digital converter, and a digital signal processor. The optical interface is configured to receive first local oscillator light from a laser outside the optical transceiver; the mixer is configured to receive the local oscillator light and receive signal light modulated on laser light; the polarization-maintaining optical waveguide is configured to connect the optical interface and the optical receiver, where a polarization state of the local oscillator light remains unchanged when being transmitted in the polarization-maintaining optical waveguide; the optical-to-electrical converter and an analog-to-digital converter are configured to perform optical-to-electrical conversion and analog-to-digital conversion on the mixed light to obtain a digital electrical signal; and the digital signal processor is configured to process the digital electrical signal to obtain data.