Systems and methods for reducing rotation sensing errors from laser source signal and modulation cross-talk are provided herein. An RFOG includes a fiber optic resonator; a first laser source that produces a first light wave at a first carrier frequency and a first cross-talked portion at a second carrier frequency wave for propagating in a first direction, wherein a second cross-talked portion propagates in a second direction that is opposite to the first direction; a second laser source that produces a second light wave for propagating in the second direction at a second carrier frequency, and having a third cross-talked portion that propagates in the first direction, a first modulator that modulates the first light wave by suppressing light at the first carrier frequency and the second cross-talked portion at the second carrier frequency, and photodetectors that generate signals from the modulated first light wave and the second light wave.

Systems and methods for calibrating a Raman amplifier in a photonic line system of an optical network are provided. A method, according to one implementation, includes the step of setting the gain of a plurality of pump lasers of a Raman amplifier to a safe level. For example, the pump lasers are configured to operate at different wavelengths. Also, the Raman amplifier is connected to a fiber span having a specific fiber-type. The safe can be defined as a level that keeps adverse intermodulation effects below a predetermined threshold regardless of the specific fiber-type. In addition, the method includes the step of increasing the gain of the pump lasers without prior knowledge of the specific fiber-type of the fiber span while keeping the adverse intermodulation effects below the predetermined threshold.

Systems and methods for reducing rotation sensing errors from laser source signal and modulation cross-talk are provided herein. An RFOG includes a fiber optic resonator; a first laser source that produces a first light wave at a first carrier frequency and a first cross-talked portion at a second carrier frequency wave for propagating in a first direction, wherein a second cross-talked portion propagates in a second direction that is opposite to the first direction; a second laser source that produces a second light wave for propagating in the second direction at a second carrier frequency, and having a third cross-talked portion that propagates in the first direction, a first modulator that modulates the first light wave by suppressing light at the first carrier frequency and the second cross-talked portion at the second carrier frequency, and photodetectors that generate signals from the modulated first light wave and the second light wave.

An optical communication device includes an excitation light source that outputs excitation light, a multiplexer that multiplexes signal light and the excitation light outputted from the excitation light source, a first nonlinear optical medium into which the multiplexed excitation light and the signal light are inputted, and a second nonlinear optical medium that is coupled to the first nonlinear optical medium in series and has an optical property different from that of the first nonlinear optical medium.

A technique is provided for producing a quality of transmission estimator for optical transmissions. The technique includes defining a local dispersion value, defining a dispersion increment, and performing a propagation calculation of an optical signal along an elementary section. The elementary section is a propagation medium characterized by the local dispersion value. The elementary section length may correspond to the dispersion increment. The optical signal, which is incoming in the elementary section, is previously affected by a cumulative dispersion value equal to an integer number of the dispersion increment. For each elementary section, a variance of noise is determined, the noise representing a distortion due to Kerr nonlinear field contributions in the elementary section. For each couple of elementary sections, a covariance of noise is determined between the couple of elementary sections. The variances and covariances may be stored in a look-up table of a data repository.

A measurement apparatus includes: a light source unit configured to generate optical signals of, from among n+1 frequencies (n is an integer of 3 or larger) at a predetermined frequency interval, n frequencies except for a target frequency, and output the generated optical signals to an optical transmission path that is a measurement target; an optical power measurement device configured to measure of an optical signal of the target frequency output from the optical transmission path and generated in the optical transmission path as a result of four-wave-mixing of the optical signals of the n frequencies; and a processor configured to determine a power spectrum density of non-linear interference noise that occurs in the optical transmission path, by multiplying the power of the optical signal of the target frequency by an adjustment value.

A method for preventing nonlinear interference in an optical communication system. The method may include selecting an optical signal of a first optical channel. The method may include determining an estimate of inter-channel nonlinear interference to the optical signal of the first optical channel. The inter-channel nonlinear interference may be generated by one or more optical signals transmitted over a second optical channel in the optical communication system. The method may include determining one or more linear filters based on the estimate of the inter-channel nonlinear interference. The method may include pre-distorting an optical signal for transmission over the second optical channel using the one or more linear filters. The pre-distorted optical signal may be configured for reducing the inter-channel nonlinear interference to the first optical signal of the first optical channel. The method may include transmitting the pre-distorted optical signal over the second optical channel through an optical transmission medium.

A method for preventing nonlinear interference in an optical communication system. The method may include selecting an optical signal of a first optical channel. The method may include determining an estimate of inter-channel nonlinear interference to the optical signal of the first optical channel. The inter-channel nonlinear interference may be generated by one or more optical signals transmitted over a second optical channel in the optical communication system. The method may include determining one or more linear filters based on the estimate of the inter-channel nonlinear interference. The method may include pre-distorting an optical signal for transmission over the second optical channel using the one or more linear filters. The pre-distorted optical signal may be configured for reducing the inter-channel nonlinear interference to the first optical signal of the first optical channel. The method may include transmitting the pre-distorted optical signal over the second optical channel through an optical transmission medium.

A measurement apparatus includes: a light source unit configured to generate optical signals of, from among n+1 frequencies (n is an integer of 3 or larger) at a predetermined frequency interval, n frequencies except for a target frequency, and output the generated optical signals to an optical transmission path that is a measurement target; an optical power measurement device configured to measure of an optical signal of the target frequency output from the optical transmission path and generated in the optical transmission path as a result of four-wave-mixing of the optical signals of the n frequencies; and a processor configured to determine a power spectrum density of non-linear interference noise that occurs in the optical transmission path, by multiplying the power of the optical signal of the target frequency by an adjustment value.

A technology is described for a Photonic Integrated Circuit (PIC) radio frequency (RF) in-phase quadrature phase (I/Q) correlator. The PIC RF Correlator can comprise two optical waveguides to receive first and second optical signals that are modulated by first and second RF signals, respectively. Two 1 to M optical splitters can split the first and second RF modulated optical signals. Optical delay lines can delay the M split first RF modulated optical signals. M optical balanced couplers can receive and combine the M first delayed RF modulated optical signals with the M split second RF modulated optical signals. Balanced photodetectors can output a differential integration on the first and second combined RF modulated optical signals for in-phase and quadrature phase signals. A processor can add the outputs of the M optical balanced photodetectors to form a frequency domain correlated signal of the first and second RF signals with real and imaginary parts.