A first resistor connected in parallel to a semiconductor optical modulator having first ends, the first resistor and first ends connected to a reference potential. A first end of a first transmission line is connected to second ends of the semiconductor optical modulator and the first resistor. A second transmission line is connected in series to the first transmission line and has an impedance lower than that of the first resistor. A first end of the second transmission line is connected to a second end of the first transmission line. A third transmission line is connected in series to the first and second transmission lines and has an end connected to a second end of the second transmission line, and has an impedance equal to that of the first transmission line. A second resistor and a capacitor are connected in series between the third transmission line and the reference potential.

A digital-electrical to analog-optical converter for converting a N-bit digital data signal uses a non-linear optical element that is susceptible to the Kerr effect. N digitally modulated optical bit stream sources are co-polarized and modulated according to individual bit streams of the digital data. The co-polarized digitally modulated signals interact with a polarized probe signal in the optical element causing the polarization of the probe signal to be changed. Propagating the polarization-changed probe signal output from the optical element through a polarizer provides an amplitude modulated optical signal corresponding to the N-bit digital signal.

A method includes generating, using a transmitter, an optical signal for each fiber incoherently combined in a fiber bundle. The method also includes transmitting the optical signal from each fiber as pulses at a target. The method further includes receiving, using a receiver array, the pulses of the optical signals and identifying one or more parameters of the target based on the pulses of the optical signals.

The present disclosure provides a modulation method, apparatus, and system for imaging scanning signal synchronization. The method includes: transmitting control signals, wherein the control signals include a galvanometer driving signal, a laser scanning signal, and a camera exposure signal, the galvanometer driving signal and the camera exposure signal have a same period, and the laser scanning signal enables laser to be emitted for N times within time for enabling positive oscillation of a galvanometer in one period of the galvanometer driving signal; measuring an actual signal waveform of the galvanometer, and obtaining a noise-reduced waveform by filtering and de-noising the actual signal waveform; performing a waveform comparison detection on the noise-reduced waveform and a corresponding control waveform for the galvanometer driving signal to obtain a waveform deviation; and adjusting the control signals based on the waveform deviation and transmitting the adjusted control signals.

An optical signal transmission method according to an embodiment of the disclosure is an optical signal transmission method in which a processor performs at least part of each operation, and may include an operation of receiving a data stream, an operation of separating at least part of the data stream into three channels, modulating the separated data streams respectively according to M-ary frequency shift keying (M-FSK) scheme so as to produce an FSK modulated signal, an operation of combining a plurality of FSK modulated signals modulated respectively in the three channels, and producing a color modulated signal according to a bit-color mapping table set in advance, and an operation of transmitting the color modulated signal by controlling a light source of the same optical channel based on the color modulated signal.

Embodiments of the present invention disclose an optical signal transmission system and an optical signal transmission method. A specific solution is as follows: a first coherent transceiver is configured to: convert N channels of downlink data into N modulating signals, convert the N modulating signals into a first wavelength division multiplexing signal, and send the first wavelength division multiplexing signal to an optical transport unit; the optical transport unit is configured to: receive the first wavelength division multiplexing signal, convert the first wavelength division multiplexing signal into N second optical signals, and correspondingly send the N second optical signals to N second coherent transceivers; and one of the N second coherent transceivers is configured to: receive the N second optical signals, and process the N second optical signals to obtain information in downlink data carried in the N second optical signals.

A method for tuning a power characteristic of an optical frequency comb includes controlling a modulating light source according to a plurality of modulation parameters to generate an optical frequency comb including a plurality of optical tones. Additionally, at least one of the plurality of modulation parameters is changed until a total power of the plurality of optical tones is greater than or equal to a minimum threshold value. Furthermore, at least one of the plurality of modulation parameters are changed until respective powers of each of the plurality of optical tones are within a predetermined proximity to respective target powers of each of the plurality of optical tones.

An optical signal transmission method according to an embodiment of the disclosure is an optical signal transmission method in which a processor performs at least part of each operation, and may include an operation of receiving a data stream, an operation of separating at least part of the data stream into three channels, modulating the separated data streams respectively according to M-ary frequency shift keying (M-FSK) scheme so as to produce an FSK modulated signal, an operation of combining a plurality of FSK modulated signals modulated respectively in the three channels, and producing a color modulated signal according to a bit-color mapping table set in advance, and an operation of transmitting the color modulated signal by controlling a light source of the same optical channel based on the color modulated signal.

Techniques for transmitting an optical signal through optical fiber with an improved cost effective stimulated Brillouin scattering (SBS) suppression include externally modulating a light beam emitted from a light source with a high frequency signal. The light beam is also modulated externally with an RF information-carrying signal. The high frequency signals are at least twice a highest frequency of the RF signal. The high frequency signals modulating the light source can be gain and phase adjusted by the first set of gain and phase control circuit to achieve a targeted spectrum shape. The adjusted high frequency signals then are split, providing a portion of the split signals to modulate the light source and another portion of the split signals to the second set of phase and gain control circuit for adjusting a phase/gain. The output of second set of phase and gain control circuits can be applied to the external modulator to eliminate intensity modulation caused by the corresponding high frequency signals that modulate the light source. The spread spectrum for SBS suppression or the optical transmitter's SNR is further improved by cancelling a beat between SBS suppression modulation tones and out of band distortion spectrum of information bearing RF signal.

The invention relates to a method for decoding (10) a modulated light signal (35) carrying a digital data set, the decoding method (10) comprising a step of searching (12, 13, 14, 15) for at least two frequencies of oscillation of a digital transcription of the light signal detected by a photodetector (23), each frequency of oscillation being representative of a logic value of the bits constituting the digital data carried by the light signal. Advantageously, a most significant bit is represented by a first frequency of oscillation and a least significant bit is represented by a second frequency of oscillation, the first frequency of oscillation being chosen so as to form, at the photodetector (23), a digital signal that is larger than that formed by the second frequency of oscillation by at least 4 elementary detection units of said photodetector (23).

The invention also relates to an optoelectronic system (20) that implements a decoding method (10) of this kind.