Embodiments of the invention include a phase adjustor for adjusting a phase angle of a local oscillator relative to a phase angle of a signal input of a Device Under Test (DUT). Some embodiments include a laser source for a lightwave component analyzer and an optical phase adjustor. The lightwave component analyzer drives a first test input to the DUT. An output of the DUT drives an output of the optical phase adjustor adapted to couple to an oscillator input to the DUT. A monitor selector is also included that accepts at least two outputs of the DUT and is structured to transmit a selected output of the DUT to the phase adjust driver. The phase adjust driver is structured to drive the optical phase adjustor with a control signal based on the output of the DUT that is selected by the monitor selector.

An optical assembly for optical signal processing: including a first input for coupling in a first light signal; a second input for coupling in a second light signal; a first beam splitter for splitting the first light signal into a first part and a second part; a second beam splitter for splitting the second light signal into a first part and a second part; a superposing unit; a detector; an electronic signal processing unit; at least one actuating unit; and a delay line for generating a delay of the running time of the first part of the first light signal and of the first part of the second light signal up to the superposing unit. The delay line is configured such that the first part of the first light signal and the first part of the second light signal pass through the delay line in opposite directions.

The present invention, which is used for continuous variable quantum key distribution (CVQKD) with asynchronous local oscillators, relates to a system for performing a phase compensation of a scheme of using LO phase estimation and feedback at a receiver (Bob) using a pilot signal from a transmitter (Alice) and a scheme of measuring quantum state data using an LO having a predetermined phase at the receiver (Bob) and estimating and feeding back an LO phase through multi-dimensional reconciliation (MDR).

The present invention, which is used for continuous variable quantum key distribution (CVQKD) with asynchronous local oscillators, relates to a system for performing a phase compensation of a scheme of using LO phase estimation and feedback at a receiver (Bob) using a pilot signal from a transmitter (Alice) and a scheme of measuring quantum state data using an LO having a predetermined phase at the receiver (Bob) and estimating and feeding back an LO phase through multi-dimensional reconciliation (MDR).

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 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 collected seed source may enable upstream communications at varying wavelengths. The end device may provide upstream communications by externally modulating a signal generated by the injection locked laser diode.

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 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 collected seed source may enable upstream communications at varying wavelengths. The end device may provide upstream communications by externally modulating a signal generated by the injection locked laser diode.

A reception apparatus includes: a receiving unit configured to coherently detect an optical signal and output an electrical signal containing a modulated signal and a pilot signal; a first compensating unit configured to detect a frequency of the pilot signal by performing a DFT of the electrical signal, and determine and compensate for frequency error in the electrical signal based on a reference frequency; a frequency converting unit configured to convert the frequency of the pilot signal after the compensating such that the frequency of the pilot signal is lowered by the reference frequency; and a second compensating unit configured to determine frequency error in the modulated signal after the compensating by performing a DFT on the pilot signal after the frequency converting and detecting a frequency of the pilot signal after the frequency converting.

A reception apparatus includes: a receiving unit configured to coherently detect an optical signal and output an electrical signal containing a modulated signal and a pilot signal; a first compensating unit configured to detect a frequency of the pilot signal by performing a DFT of the electrical signal, and determine and compensate for frequency error in the electrical signal based on a reference frequency; a frequency converting unit configured to convert the frequency of the pilot signal after the compensating such that the frequency of the pilot signal is lowered by the reference frequency; and a second compensating unit configured to determine frequency error in the modulated signal after the compensating by performing a DFT on the pilot signal after the frequency converting and detecting a frequency of the pilot signal after the frequency converting.

A receiver system is provided for receiving a coherent Pulse Amplitude Modulation (PAM) encoded signal. The receiver system may include an optical polarization component configured to modulate a polarization of the received coherent PAM encoded signal. The receiver system may further include a digital signal processor (DSP) configured to perform polarization recovery between the received coherent PAM encoded signal and the LO signal using a first control loop, and to perform phase recovery between the received coherent PAM encoded signal and the LO signal using a second control loop.

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.