H04B10/2557

Apparatus and method for shifting a frequency of an optical signal
11588557 · 2023-02-21 · ·

A system and method for applying a time-varying phase shift to an optical signal is described. Such a phase shift results in a frequency shift of the optical signal, which can be useful for instance in sensing applications. The design uses cross phase modulation (XPM) in a nonlinear medium such as optical fiber. The pump producing the XPM experiences a change in energy along the medium, for instance due to loss. The pump and signal have mismatched group velocities such that they walk-off each other in time, and the pump pulse repetition rate is chosen so that it has a specific relationship with respect to the walk-off. The design is compatible with very low signal loss and does not require high fidelity electrical control signals. It is capable of high-efficiency one-directional serrodyne frequency shifts, as well as producing symmetric frequency shifts. It can also be made polarization independent.

Apparatus and method for shifting a frequency of an optical signal
11588557 · 2023-02-21 · ·

A system and method for applying a time-varying phase shift to an optical signal is described. Such a phase shift results in a frequency shift of the optical signal, which can be useful for instance in sensing applications. The design uses cross phase modulation (XPM) in a nonlinear medium such as optical fiber. The pump producing the XPM experiences a change in energy along the medium, for instance due to loss. The pump and signal have mismatched group velocities such that they walk-off each other in time, and the pump pulse repetition rate is chosen so that it has a specific relationship with respect to the walk-off. The design is compatible with very low signal loss and does not require high fidelity electrical control signals. It is capable of high-efficiency one-directional serrodyne frequency shifts, as well as producing symmetric frequency shifts. It can also be made polarization independent.

Optical transmitter and transmission method

An optical transmitter, having an encoder and modulator, transmits a data signal. The encoder maps information bits of the data signal to a symbol in eight-dimensional (8D) constellation space spanned by vectors IXT1, QXT1, IYT1, QYT1, IXT2, QXT2, IYT2, QYT2, wherein I and Q are in-phase and quadrature components of an optical carrier, X and Y are orthogonal polarizations of the optical carrier, and T1 and T2 are two consecutive transmission time slots, by selecting the symbol from a set of constellation points in the 8D space. The modulator uses the symbol in the two consecutive transmission time slots to modulate two carrier waves, and to transmit the two carrier waves over the orthogonal polarizations of the optical carrier. The set of constellation points do not include any constellation point with parallel Stokes vectors in the two consecutive transmission time slots but comprise constellation points with orthogonal Stokes vectors.

Optical transmitter and transmission method

An optical transmitter, having an encoder and modulator, transmits a data signal. The encoder maps information bits of the data signal to a symbol in eight-dimensional (8D) constellation space spanned by vectors IXT1, QXT1, IYT1, QYT1, IXT2, QXT2, IYT2, QYT2, wherein I and Q are in-phase and quadrature components of an optical carrier, X and Y are orthogonal polarizations of the optical carrier, and T1 and T2 are two consecutive transmission time slots, by selecting the symbol from a set of constellation points in the 8D space. The modulator uses the symbol in the two consecutive transmission time slots to modulate two carrier waves, and to transmit the two carrier waves over the orthogonal polarizations of the optical carrier. The set of constellation points do not include any constellation point with parallel Stokes vectors in the two consecutive transmission time slots but comprise constellation points with orthogonal Stokes vectors.

Optical encoder devices and systems

Devices, systems and methods for encoding information using optical components are described. Information associated with a first optical signal (e.g., an optical pump) is encoded onto the phase of a second optical signal (e.g., an optical probe) using cross phase modulation (XPM) in a non-linear optical medium. The optical signals are multiplexed together into the nonlinear optical medium. The probe experiences a modified index of refraction as it propagates through the medium and thus accumulates a phase change proportional to the intensity of the pump. The disclosed devices can be incorporated into larger components and systems for various applications such as scientific diagnostics, radar, remote sensing, wireless communications, and quantum computing that can benefit from encoding and generation of low noise, high resolution signals. Examples of the encoded information includes intrinsic noise from the optical source, or others signals of interest, such as electrical, optical, X-ray, or high-energy particle signals.

Optical encoder devices and systems

Devices, systems and methods for encoding information using optical components are described. Information associated with a first optical signal (e.g., an optical pump) is encoded onto the phase of a second optical signal (e.g., an optical probe) using cross phase modulation (XPM) in a non-linear optical medium. The optical signals are multiplexed together into the nonlinear optical medium. The probe experiences a modified index of refraction as it propagates through the medium and thus accumulates a phase change proportional to the intensity of the pump. The disclosed devices can be incorporated into larger components and systems for various applications such as scientific diagnostics, radar, remote sensing, wireless communications, and quantum computing that can benefit from encoding and generation of low noise, high resolution signals. Examples of the encoded information includes intrinsic noise from the optical source, or others signals of interest, such as electrical, optical, X-ray, or high-energy particle signals.

OPTICAL TRANSMITTER AND TRANSMISSION METHOD

An optical transmitter transmits a data signal. The optical transmitter has an encoder configured to encode the data signal by selecting based on a bit sequence a first symbol and a second symbol from a set of four symbols for each one of at least two transmission time slots. The optical transmitter further has a modulator configured to use in each transmission time slot the first symbol to modulate a first carrier wave and the second symbol to modulate a second carrier wave, and to transmit the two carrier waves over orthogonal polarizations of an optical carrier. Symbols in consecutive transmission time slots have non-identical polarization states.

OPTICAL TRANSMITTER AND TRANSMISSION METHOD

An optical transmitter transmits a data signal. The optical transmitter has an encoder configured to encode the data signal by selecting based on a bit sequence a first symbol and a second symbol from a set of four symbols for each one of at least two transmission time slots. The optical transmitter further has a modulator configured to use in each transmission time slot the first symbol to modulate a first carrier wave and the second symbol to modulate a second carrier wave, and to transmit the two carrier waves over orthogonal polarizations of an optical carrier. Symbols in consecutive transmission time slots have non-identical polarization states.

OPTICAL ENCODER DEVICES AND SYSTEMS

Devices, systems and methods for encoding information using optical components are described. An example photonic filtered sampler includes a spectral shaper configured to receive an optical pulse train, a dispersive element positioned to receive an output of the spectral shaper and to expand spectral contents thereof in time, and a modulator configured to receive an output of the dispersive element and a radio frequency (RF) signal, and to produce a modulated output optical signal in accordance with the RF signal. In this configuration, one or more characteristics of the modulated output optical signal is determined based on a spectral shape provided by the spectral shaper and dispersive properties of the dispersive element.

OPTICAL ENCODER DEVICES AND SYSTEMS

Devices, systems and methods for encoding information using optical components are described. An example photonic filtered sampler includes a spectral shaper configured to receive an optical pulse train, a dispersive element positioned to receive an output of the spectral shaper and to expand spectral contents thereof in time, and a modulator configured to receive an output of the dispersive element and a radio frequency (RF) signal, and to produce a modulated output optical signal in accordance with the RF signal. In this configuration, one or more characteristics of the modulated output optical signal is determined based on a spectral shape provided by the spectral shaper and dispersive properties of the dispersive element.