System and methods of measuring nonlinear interference (NLI) on a per-span basis in an optical system with a plurality of spans are provided. The method includes steps of varying power based on phase sensitive detection method on a span under test of the plurality of spans; observing total noise, at an optical receiver, from all of the plurality of spans; and isolating noise for the span under test from the total noise based on the varying power. The optical system can be in-service with one or more traffic-carrying channels, and the varying power is small enough on the span under test which does not impact the one or more traffic-carrying channels.

A light-receiving device includes: a light guide plate that is a transparent member having, as main surfaces, a first surface and a second surface facing each other and has an emission end formed on at least one end portion of the light guide plate; a wave plate that is disposed on the first surface of the light guide plate and converts an optical signal of circularly polarized light into linearly polarized light; a hologram layer that is disposed on the second surface of the light guide plate and guides a traveling direction of the optical signal converted into the linearly polarized light toward the emission end of the light guide plate; and a light receiver that receives the optical signal emitted from the emission end of the light guide plate and converts the received optical signal into an electrical signal.

A light-receiving device includes: a light guide plate that is a transparent member having, as main surfaces, a first surface and a second surface facing each other and has an emission end formed on at least one end portion of the light guide plate; a wave plate that is disposed on the first surface of the light guide plate and converts an optical signal of circularly polarized light into linearly polarized light; a hologram layer that is disposed on the second surface of the light guide plate and guides a traveling direction of the optical signal converted into the linearly polarized light toward the emission end of the light guide plate; and a light receiver that receives the optical signal emitted from the emission end of the light guide plate and converts the received optical signal into an electrical signal.

An apparatus includes a photonic integrated circuit having an optical phased array, where the optical phased array includes multiple unit cells. Each unit cell includes (i) an antenna element configured to receive optical signals and (ii) a modulator configured to phase-shift the optical signals received by the antenna element. Multiple subgroups of the unit cells in the optical phased array are configured to generate multiple combined optical signals based on the received optical signals. The apparatus also includes at least one of: (i) amplitude adjusters configured to modify amplitudes of the combined optical signals in order to compensate for amplitude modulations across a receive aperture of the optical phased array and (ii) phase modulators configured to modify phases of the combined optical signals in order to compensate for phase modulations across the receive aperture of the optical phased array.

A wavelength reference device includes a broadband optical source, a repeating filter, and a wavelength-specific filter. The source, which can be a super-luminescent light-emitting diode (SLED), emits optical power. The repeating filter, which can be a Fabray-Perot etalon, filters the optical power into a repeating spectral response, and the wavelength-specific filter attenuates the optical power of at least one predefined wavelength response within the wavelength band. The repeating filter and the wavelength-specific filter output a wavelength reference signal having the repeating spectral response attenuated at the at least one predefined wavelength response. The predefined wavelength response reduces the ambiguity that can occur in the repeating frequency locations found in the repeating spectral response. In this way, an absolute wavelength reference is intrinsically provided in the wavelength reference that removes the location ambiguity caused by the repeating spectral response.

A powered device includes a plurality of photoelectric conversion elements. The photoelectric conversion elements receive feed light. The photoelectric conversion elements are disposed such that light-receiving surfaces of the photoelectric conversion elements are arranged in a concave shape.

A powered device includes a plurality of photoelectric conversion elements. The photoelectric conversion elements receive feed light. The photoelectric conversion elements are disposed such that light-receiving surfaces of the photoelectric conversion elements are arranged in a concave shape.

A high-speed, wavelength-converting receiver that includes a housing; a high-speed, wavelength-converting layer attached to the housing and configured to absorb a first light having a first wavelength range and emit a second light having a second wavelength range, which is different from the first wavelength range; and a high-speed photodetector attached to the housing and having an active face configured to absorb the second light having the second wavelength range and generate an electrical signal. The active face of the photodetector is fully placed within the housing.

The present disclosure relates to a method for transmitting or receiving a signal by a reception device in a wireless communication system, and the method may comprise the steps of: receiving, from a transmission device, a signal modulated on the basis of a differential phase shift keying (DPSK) scheme; converting the received signal into an input signal of a spiking neural network (SNN); calculating an output value through the spiking neural network previously learned; and converting the output value into an input signal of a channel decoder.

There are provided an optical transmission apparatus that subjects a transmission signal including a plurality of sequences to Hadamard transform to obtain a signal in which a predetermined delay is added to one of the sequences, optically modulates the obtained signal, and transmits the modulated signal, and an optical reception apparatus that demodulates a reception signal received from the optical transmission apparatus by subjecting the reception signal to adaptive equalization processing with a predetermined number of taps. The optical reception apparatus includes: an adaptive equalization processing unit that subjects the reception signal to adaptive equalization processing of wavelength distortion compensation with a number of taps obtained by subtracting a number in accordance with the delay from the predetermined number of taps; a delay compensation unit that subjects the reception signal subjected to the wavelength distortion compensation to delay compensation in accordance with the delay; and an inverse Hadamard transform unit that subjects the reception signal subjected to the delay compensation to inverse Hadamard transform.