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.

To suppress the deterioration of the characteristics of a MIMO equalizer as well as minimizing an increase in circuit size in spite of the occurrence of signal spectrum narrowing and asymmetric spectrum degradation, a wavelength-division multiplexing optical transmission system (10) according to an embodiment includes a transmitter (1) that generates one channel signal by wavelength-division multiplexing a plurality of subcarrier signals so as to overlap each other and transmits the channel signal, and a receiver (2) that separates a received channel signal into subcarrier signals, and performs equalization using an MIMO equalizer (3) including a FDE-MIMO equalizer (4) and a TDE-MIMO equalizer (5) on each of the separated subcarrier signals.

A sourceless co-packaged optical-electrical chip can include a plurality of different optical transceivers, each of which can transmit to an external destination or internal components. Each of the transceivers can be configured for a different modulation format, such as different pulse amplitude, phase shift key, and quadrature amplitude modulation formats. Different light sources provide light for processing by the transceivers, where the light source and transceivers can be configured for different applications (e.g., different distances) and data rates. An optical coupler can combine the light for the different transceivers for input into the sourceless co-packaged optical-electrical chip via a polarization maintaining media (e.g., polarization maintaining few mode fiber and polarization maintaining single mode fiber), where another coupler operates in splitting mode to separate the different channels of light for the different transceivers according to different co-packaged configurations.

Planar assemblies for coupling a plurality of optical transceivers to the same optical fiber. For example, the optical transceivers may be PON transceivers functioning according to different data rates and/or different modulation formats. Each optical transceiver communicates using one or more different wavelength channels. At least some of the disclosed planar assemblies are scalable to couple various numbers of optical transceivers to the same end face of an optical fiber, e.g., by fixing a corresponding number of passive, slab-like optical filters to a substantially planar surface of the support substrate to which the optical transceivers are also fixed adjacent and along. Some embodiments may employ various bulk lenses fixed to said planar surface to suitably relay light-beam segments between the end face of the fiber and the optical transceivers and/or between the different slab-like optical filters.

A wavelength tunable light source includes: a common wavelength filter that has periodic transmission peak wavelengths or reflection peak wavelengths and is commonly used for a plurality of channels; a wavelength tunable filter that is coupled to the common wavelength filter and has a one-input and multiple-output configuration which has a plurality of output ports, and that has a plurality of transmission peak wavelengths corresponding to the plurality of channels at the plurality of output ports; and a plurality of gain media optically coupled to the plurality of output ports of the wavelength tunable filter, wherein a plurality of laser cavities that perform laser oscillation at a plurality of different wavelengths are formed between the common wavelength filter and the plurality of gain media.

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 cyclic wavelength band permutation device (31) includes as many wavelength band converters (32a to 32c) as the wavelength bands of optical signals (S1, C1, and L1), and the wavelength band converters are individually connected to the output terminals of corresponding optical amplifiers among a plurality of optical amplifiers (17a to 17c) connected to an optical fiber (16) in an inserted manner. When a wavelength-multiplexed signal beam obtained by multiplexing optical signals in different wavelength bands is multiband-transmitted through an optical fiber while being amplified by the plurality of optical amplifiers, each wavelength band converter performs a cyclic permutation process of transitioning or converting an optical signal allocated to the shorter wavelength band side in the bands of the optical fiber to the longer wavelength band side, and also transitioning or converting an optical signal allocated to the longest wavelength band to the shortest wavelength band.

Disclosed are an optical path system for quantum communication and a quantum communication method. The optical path system for quantum communication includes a light source module, an intensity and polarization modulation module, a polarization maintaining interference ring, a phase and intensity modulation module, a first isolator, a first polarization beam splitter, a second isolator, a beam splitter, a second polarization beam splitter, a second phase modulator, and a 90-degree Faraday rotator mirror. An optical signal may pass through a first polarization beam splitter, bypass a phase and intensity modulation module, and directly reach a polarization maintaining interference ring, thereby solving a problem of series mode interference in an optical signal circuit, and greatly improving a modulation speed of the circuit.

Disclosed in a communication device including a light source over a substrate and a liquid crystal element over the light source. The light source includes first to third light-emitting elements and first to third light-guide plates. The first light-emitting element is configured to emit first light. The second light-emitting element is configured to emit second light different in wavelength from the first light. The third light-emitting element is configured to emit third light different in wavelength from the first light and the second light. The first to third light-guide plates are arranged in a stripe shape and is configured so that the first light to the third light are respectively incident thereon. The liquid crystal element overlaps the first to third light-guide plates. The liquid crystal element is configured to independently control irradiation regions of the first to third lights incident through the first to third light-guide plates.

The present invention addresses the problem of improving data transmission/reception equipment and transmission efficiency per hour. A light output unit 111 of a light transmitting/receiving device outputs n optical signals (where n is an integer value of 2 or more), each with a different wavelength, based on n respective pieces of data to be transmitted. From the n optical signals, a multiplexer 112 produces an optical signal multiplexed with respect to wavelength. From the multiplexed optical signal, an encryption unit 113 produces an encrypted signal by performing multi-level modulation on the basis of a Y-00 protocol. The problem is solved thereby.