A method and a system for adding a floating analog voltage signal over a reference analog voltage signal. The system and the method may accurately control the value of the floating analog voltage signal—using an optical feedback path, and may directly add the floating analog voltage signal over the reference analog voltage signal.

During operation, the system receives an optical input signal, and also receives a reference optical frequency comb (OFC) signal. Next, the system uses a gapless spectral demultiplexer to spectrally slice the optical input signal to produce a set of spectral slices. The system also uses a high-contrast demultiplexer to strongly isolate each combline of the reference OFC signal to produce a set of reference comblines. Next, in a parallel manner, the system demodulates each spectral slice in the set of spectral slices centered on a single reference combline in the set of reference comblines to produce a set of baseband I/Q signals, wherein each spectral slice is demodulated based on a known code sequence. The system then digitizes the set of baseband I/Q signals to produce a set of digitized signals. Finally, the system processes the set of digitized signals to directly reconstruct a waveform for the optical input signal.

An optical analog-to-digital (AD) converter includes, wherein the optical AD converter converts an analog signal of information included in inputted signal light into a digital signal, and is formed of N stages corresponding to a number N of bits of the digital signal, optical waveguides configured to respectively guide the signal light, base light obtained by branching local light, and reference light obtained by branching the local light, a light receiver configured to detect and compare light levels of the signal light and the reference light, and output a binary comparison result, and an optical modulator configured to variably control a light level of the base light, based on the binary comparison result, in each stage of the N stages, wherein an output variably controlled of the optical modulator is multiplexed with the reference light of a next stage.

An optical analog-to-digital (AD) converter includes, wherein the optical AD converter converts an analog signal of information included in inputted signal light into a digital signal, and is formed of N stages corresponding to a number N of bits of the digital signal, optical waveguides configured to respectively guide the signal light, base light obtained by branching local light, and reference light obtained by branching the local light, a light receiver configured to detect and compare light levels of the signal light and the reference light, and output a binary comparison result, and an optical modulator configured to variably control a light level of the base light, based on the binary comparison result, in each stage of the N stages, wherein an output variably controlled of the optical modulator is multiplexed with the reference light of a next stage.

A frequency separator includes a plurality of filters to separate light having a plurality of optical pulses, each of the optical pulses having one of a plurality of frequencies, into a plurality of light components, each of the light components being to have one of a plurality of frequency bands corresponding to the plurality of frequencies, in which among the plurality of filters, a center frequency of a first frequency band of a first filter and a center frequency of a second frequency band, adjacent to the first frequency band, of a second filter are separated beyond a bandwidth of each of the first and second frequency bands.

A frequency separator includes a plurality of filters to separate light having a plurality of optical pulses, each of the optical pulses having one of a plurality of frequencies, into a plurality of light components, each of the light components being to have one of a plurality of frequency bands corresponding to the plurality of frequencies, in which among the plurality of filters, a center frequency of a first frequency band of a first filter and a center frequency of a second frequency band, adjacent to the first frequency band, of a second filter are separated beyond a bandwidth of each of the first and second frequency bands.

A method and a system for adding a floating analog voltage signal over a reference analog voltage signal. The system and the method may accurately control the value of the floating analog voltage signal—using an optical feedback path, and may directly add the floating analog voltage signal over the reference analog voltage signal.

A method and a system for adding a floating analog voltage signal over a reference analog voltage signal. The system and the method may accurately control the value of the floating analog voltage signal—using an optical feedback path, and may directly add the floating analog voltage signal over the reference analog voltage signal.

Methods and apparatus for tuning a photonics-based component. An opto-electrical detector is configured to output an electrical signal based on a measurement of light intensity of the photonics-based component, the light intensity being proportional to an amount of detuning of the photonics-based component. Analog-to-digital conversion (ADC) circuitry is configured to output a digital signal based on the electrical signal output from the opto-electrical detector. Feedback control circuitry is configured to tune the photonics-based component based, at least in part, on the digital signal output from the ADC circuitry.

The disclosure describes various aspects of a system with scalable and programmable coherent waveform generators. A network and digital-to-analog conversion (DAC) cards used by the network are described where each DAC card has a clock divider/replicator device with an input SYNC pin, a digital logic component, and one or more DAC components, and each output of the DAC components is used to control optical beams for a separate qubit of a quantum information processing (QIP) system. The network also includes a first distribution network to provide a clock signal to the clock divider/replicator device in the DAC cards, and a second distribution network to provide a start signal to the DAC cards, where the start signal is used by the digital logic component in the DAC card to assert the input SYNC pin when the start signal is asserted unless it is masked by the digital logic component.