System for pulsed laser optical data transmission with receiver recoverable clock

Abstract

A system includes an optical transmitter configured to modulate a pulsed laser signal based on a plurality of data signals to form a plurality of modulated optical data signals, perform optical time division multiplexing of the plurality of modulated optical data signals to obtain a multiplexed optical data signal, and transmitting the multiplexed optical data signal together with an optical clock signal derived from the pulsed laser signal; and an optical receiver comprising a clock recovery branch configured to recover the optical clock signal to a plurality of phase shift recovered optical clock signals and a data branch having a plurality of saturable absorbers (SAs), each SA being in optical communication with one of the phase shift recovered optical clock signals, and configured to receive the multiplexed optical data signal and to transmit one of the plurality of modulated optical data signals according to the recovered optical clock signal.

Description

[0001] This application is a divisional application of Chinese application filed on January 5, 2022, with application number 202280009276.9 and entitled "System for transmitting pulsed laser optical data with a receiver recoverable clock". Cross-references to related applications

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 142,684, filed January 28, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The various system embodiments disclosed herein generally relate to signal transmission, and more specifically to systems for transmitting high data rate optical signals. Background Technology

[0004] Coherent and incoherent optical transceivers used for high data rate transmissions such as 400 Gbps and above typically employ digital signal processors (DSPs). The DSP provides one or more of the following to achieve such high rates: pre- or post-dispersion compensation, other channel impairments, multiplexing and demultiplexing, implementation of advanced modulation formats, and / or error correction, such as when using PAM4 (or other modulations).

[0005] The required DSPs are power-intensive—typically 8W for a DSP in a 400Gbps data rate system, or even higher for higher data rates, thus increasing the power demands of high-bit-rate systems. Furthermore, multiplexing of multiple data channels and additional signal processing of electrical signals introduce latency into signal transmission. Moreover, DSPs have a limited maximum processing capacity due to limitations in electrical processing. Therefore, it is desirable to provide a transmission system with high data rates without requiring a DSP, thereby reducing power consumption and latency and overcoming the electrical bandwidth bottleneck. Summary of the Invention

[0006] The embodiments disclosed herein relate to systems, apparatus, and methods for implementing high data rate optical signals with reduced power consumption and reduced latency. The systems described herein utilize all-optical transmitters and receivers, thereby eliminating the need for a DSP, which reduces the power requirements and latency of systems transmitting equivalent data rates. The all-optical transmitter-receiver arrangement also reduces computational complexity (such as that required by a DSP). In some embodiments, the all-optical transmitter and receiver are configured as an integrated circuit (IC) sharing a semiconductor substrate to further reduce power and size requirements.

[0007] To set up an all-optical receiver, a clock (local oscillator) is needed at the receiver to power the transmitted modulated signal. Currently disclosed systems use modulated pulsed lasers for data transmission, utilizing periodic pulses as the clock. The laser-based clock is transmitted along with the data signal and recovered by the receiver, thus serving as the desired local oscillator. In some embodiments, a quadrature transverse mode is used, with one channel carrying data and the other carrying the clock. In some embodiments, separate data and clock channels are transmitted to the receiver. To enable all-optical demodulation based on the received clock, the receiver advantageously includes a saturable absorber (SA) configured to transmit the received data pulses when saturated with clock pulses, thereby recovering the transmitted data signal.

[0008] In some embodiments, optical time-division multiplexing (OTDM) is configured for the transmission of multiple data channels. The use of optical multiplexing reduces latency and complexity compared to electrical multiplexing, such as in DSPs. In some embodiments, the systems disclosed herein may be repetitive, or an integrated WDM system may be provided for the transmission of a greater number of channels per fiber optic cable. In some embodiments, single-mode fiber optic cables are used with unidirectional operation. In some embodiments, full-duplex fiber optic cables are used with bidirectional operation. Furthermore, dispersion management is also performed optically in the receiver to compensate for dispersion during transmission and dispersion that may be caused by the saturable absorber. As mentioned above, the use of dispersion management reduces the computational complexity of the solution.

[0009] In some embodiments, a system includes: an optical transmitter comprising a pulsed laser for outputting a pulsed laser signal, wherein the optical transmitter is configured to modulate the pulsed laser signal based on a plurality of data signals to form a plurality of modulated optical data signals, optically time-division multiplex the plurality of modulated optical data signals to obtain a multiplexed optical data signal, and transmit the multiplexed optical data signal together with an optical clock signal derived from the pulsed laser signal; and an optical receiver comprising a clock recovery branch and a data branch, wherein the clock recovery branch is configured to recover and phase-shift the optical clock signal to a plurality of phase-shifted recovered optical clock signals, wherein the data branch comprises a plurality of independent optical signals (SAs), and wherein each SA is optically in communication with one of the plurality of phase-shifted recovered optical clock signals, and is configured to receive the multiplexed optical data signal and transmit one of the modulated optical data signals received in the multiplexed optical data signal according to one of the plurality of phase-shifted recovered optical clock signals.

[0010] In some embodiments, the optical clock signal and the multiplexed optical data signal are transmitted by an optical transmitter in an orthogonal lateral mode over a single-mode optical fiber cable. In some embodiments, the optical clock signal and the multiplexed optical data signal are transmitted by an optical transmitter through separate cables in a full-duplex optical fiber cable. In some embodiments, a clock pulse from one of a plurality of phase-shift recovered optical clock signals saturates the corresponding SA, thereby causing the corresponding SA to release a pulse from one of a plurality of modulated optical data signals.

[0011] In some embodiments, the clock recovery branch includes a splitter and a phase shifter for extracting an optical clock signal into multiple phase-shifted optical clock signals. In some embodiments, the optical receiver further includes one or more dispersion managers configured to perform dispersion correction on multiple modulated optical data signals and multiple phase-shifted optical clock signals. In some embodiments, the optical receiver further includes an output component configured to extract multiple data signals from each of the multiple modulated optical data signals.

[0012] In some embodiments, the pulsed laser is selected from the group consisting of bulk lasers, quantum well lasers, quantum dot lasers, semiconductor mode-locked lasers, and mode-locked integrated external cavity surface-emitting lasers. In some embodiments, the pulsed laser has a pulse repetition rate between 5 GHz and 100 GHz. In some embodiments, the optical receiver includes an optical amplifier (OA). In some embodiments, the OA is a quantum dot semiconductor optical amplifier.

[0013] In some embodiments, the modulation is either pulse amplitude modulation (PAM) or quadrature amplitude modulation (QAM). In some embodiments, the plurality of data signals comprises 2-16 data signals per wavelength. In some embodiments, the plurality of data signals are digital signals and / or analog signals.

[0014] In some embodiments, a transmission system includes a first transceiver and a second transceiver, wherein each of the first transceiver and the second transceiver includes an optical transmitter, an optical receiver, and a controller, wherein each optical transmitter is configured to modulate a pulsed laser signal based on a plurality of data signals to form a plurality of modulated optical data signals, optically time-division multiplex the plurality of modulated optical data signals to obtain a multiplexed optical data signal, and transmit the multiplexed optical data signal together with an optical clock signal derived from the pulsed laser signal, and wherein each optical receiver includes a clock recovery branch and a data branch, wherein the clock recovery branch is configured to recover the optical clock signal and phase-shift it to a plurality of phase-shifted recovered optical clock signals, wherein the data branch includes a plurality of SAs, and wherein each SA optically communicates with one of the plurality of phase-shifted recovered optical clock signals and is configured to receive the multiplexed optical data signal and transmit one of the modulated optical data signals received in the multiplexed optical data signal according to one of the plurality of phase-shifted recovered optical clock signals.

[0015] In some embodiments, each controller is configured to monitor transceiver performance and to perform transmitter and receiver tuning to optimize transceiver performance. In some embodiments, monitoring includes monitoring one or more of bit error rate, data throughput, frame loss, or jitter. In some embodiments, each transceiver is formed on a common semiconductor substrate that serves as an IC.

[0016] This overview is set forth in a simplified manner to present the selection of concepts, which will be further described in the detailed descriptions below. This overview is not intended to identify key or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. Attached Figure Description

[0017] The embodiments disclosed herein are described by way of example only with reference to the following figures, in which: Figure 1A An optical system for data transmission over a single-mode optical fiber is shown according to some embodiments; Figure 1B A transmitter for use with single-mode optical fiber is shown according to some embodiments; Figure 1C An illustrative signal amplitude diagram of an optical signal within a transmitter according to some embodiments is shown; Figure 1D A receiver for use with single-mode fiber is shown according to some embodiments; Figure 1E An illustrative signal amplitude diagram of an optical signal within a receiver according to some embodiments is shown; Figure 1F and Figure 1GSeveral optical transmission systems according to some embodiments are shown; Figure 2A An optical system for data transmission over full-duplex optical fiber is shown according to some embodiments; Figure 2B A transmitter for use with full-duplex optical fiber is shown according to some embodiments; Figure 2C A coupling assembly for use with full-duplex optical fiber is shown according to some embodiments; Figure 2D A receiver for use with full-duplex optical fiber is shown according to some embodiments; Figure 2E and Figure 2F Several optical transmission systems according to some embodiments are shown. Detailed Implementation

[0018] Various aspects of the embodiments relate to systems, apparatuses, and methods for realizing high data rate optical signals with reduced power consumption, reduced latency, and reduced computational complexity. Figure 1A-1G An optical system for data transmission according to some embodiments is shown. For example... Figure 1A As shown, the optical transmission system 100 includes transceivers 108-1 and 108-2. Each transceiver 108 includes an optical transmitter 110, an optical receiver 140, and a controller 160.

[0019] Transmitter 110-1 communicates optically with receiver 140-2 via single-mode fiber optic cable 170-1 to transmit unidirectional data signal 102, and transmitter 110-2 communicates optically with receiver 140-1 via single-mode fiber optic cable 170-2 to transmit unidirectional data signal 104. In some embodiments, a single fiber optic cable 170 can be used for bidirectional optical communication, such as by using different wavelengths to transmit data signals 102 and 104. Data signals such as signals 102 and 104 are also referred to herein as “channels.” In some embodiments, each transceiver 108-1 and 108-2 is configured to share an integrated circuit (IC) on a semiconductor substrate.

[0020] Data signals 102 and 104 are electrical data signals. In some embodiments, data signals 102 and 104 are digital signals, and the laser pulse repetition rate is equal to or greater than the digital signal rate. In some embodiments, data signals 102 and 104 are analog electrical signals, and the laser pulse repetition rate is equal to or greater than the Nyquist frequency of the analog electrical signal. In some embodiments, data signals 102 and 104 are a combination of digital and analog signals. For simplicity, Figure 1A-1GThe transmission of two channels (data signals 102-1 and 102-2 and data signals 104-1 and 104-2) in each transmission direction is shown, but it should be understood that the system 100 can multiplex and transmit more than two channels. In some embodiments, 2-16 data signals per wavelength are supported.

[0021] Controller 160 is a computing device as defined herein. Controller 160-1 communicates with transmitter 110-1 and receiver 140-1, and controller 160-2 communicates with transmitter 110-2 and receiver 140-2 to control each of transceivers 108-1 and 108-2 for operation of system 100 as further described below.

[0022] Referring to Figure 1B, the components of each transmitter 110 are further described, and each transmitter 110 includes a pulsed laser 112, a polarization splitter 114, a 3dB splitter 116, a driver 118, an electro-optic (EG) modulator 120, a tunable phase shifter 122, a 3dB coupler 124, a polarization coupler 126, and a pulse shaper 128. In some embodiments, the components of the transmitter 110 are formed on a common semiconductor, which serves as an IC.

[0023] Pulsed laser 112 provides a source pulsed laser signal for optical transmission of data signal 102, which can be modulated based on data signal 102. The pulsed laser signal is also used as a clock and is transmitted along with the modulated data to enable demodulation of the data signal. In some embodiments, pulsed laser 112 operates at a fixed wavelength, denoted herein as λ1. Pulsed laser 112 emits pulses at a periodic repetition frequency. In some embodiments, pulsed laser 112 can be any of a bulk laser, a quantum well laser, a quantum dot laser, a semiconductor mode-locked laser, a high-power semiconductor laser, or a mode-locked integrated external cavity surface-emitting laser. In some embodiments, pulsed laser 112 can support pulse repetition rates between 5 GHz and 100 GHz. In some embodiments, pulsed laser 112 can support pulse repetition rates between 100 GHz and 400 GHz.

[0024] Polarization separator 114 splits the pulsed laser signal into orthogonal transverse modes. In system 100, one mode is used for data transmission, while the other is used for clock transmission. Data is transmitted on data branch 113 in TE (transverse electrical) mode, and the clock is transmitted on clock branch 111 in TM (transverse magnetic) mode, or vice versa (data on TM and clock on TE). In some embodiments, polarization separator 114 divides the pulsed laser signal intensity unequally between the two modes. Non-limiting examples of division ratios include 90 / 10 and 80 / 20. In some embodiments, polarization separator 114 divides the pulsed laser signal equally between the two modes. Both modes are expected to suffer the same distortion during transmission without affecting orthogonality.

[0025] In data branch 113, transmitter 112 provides OTDM of multiple data signals 102 (or 104). Exemplarily, for simplicity, two data signals 102-1 and 102-2, two drivers 118-1, 118-2, and two EO modulators 120-1, 120-2 are shown; however, it should be understood that multiple (more than two) data signals can be supported. A 3dB splitter 116 divides the pulsed transverse mode laser signal according to the number of supported data signals (shown here as two). In some embodiments, each data signal 102 is input to transmitter 112 via driver 118. Driver 118 can power EO modulator 120 and can adjust the electrical signal level of the input data signal 102.

[0026] The EO modulator 120 modulates the source pulsed laser signal based on the input data signal 102. In some embodiments, the EO modulator may include a digital-to-analog converter (DAC) (not shown) for processing analog electrical inputs. In some embodiments, the pulse (clock) rate and the channel rate thereby modulated are: R / (number of channels).

[0027] Various modulation schemes, including but not limited to pulse amplitude modulation (PAM) or quadrature amplitude modulation (QAM), can be applied. The tunable phase shifter 122 shifts the phases of the second and other channels to obtain a modulated (phase-shifted) channel (indicated by λ). 1S1-MOD , λ 1S2-MOD，SHIFT This causes the channel pulses to interleave when combined at the 3dB coupler 124. Coupler 124 combines the modulated (phase-shifted) channel (indicated by λ). 1S1-MOD , λ 1S2-MOD，SHIFT ), to form the OTDM output signal of data branch 113 (indicated by λ) 1OTDM Its pulse rate is: R×(number of channels).

[0028] Figure 1C The modulation (phase shift) channel (indicated by λ) is shown.1S1-MOD , λ 1S2-MOD，SHIFT The combined OTDM output of data branch 113 (indicated by λ) and data branch 113 1 OTDM ) and clock signal (indicated by λ) 1-CLOCK (Illustrative signal amplitude diagram)

[0029] Polarization coupler 126 combines the lateral modes of data branch 113 and clock branch 111 to form an orthogonal lateral signal to carry the OTDM output and clock, indicated by λ. 1 OTDM+CLOCK In some embodiments, the pulse shaper 128 shapes and equalizes the pulse. 1 OTDM+CLOCK The pulse height and shape are determined to form transmitter output 106. In some embodiments, pulse shaper 128 may be coupled to fiber optic cable 170. In some embodiments, pulse shaper 128 may be fed into a WDM multiplexer as further described below. In some embodiments, pulse shaping may be implemented using a filter bank. In some embodiments, pulse shaping may be implemented using nested unbalanced Mach-Zehnder interferometers (MZIs), ring resonators, or a combination of MZIs and ring resonators. Transmitter output 106 is transmitted toward receiver 140 over fiber optic cable 170.

[0030] In transmitter 110, controller 160 can monitor and control all components and provide automatic adjustment of adjustable components such as phase shifter 122, pulse shaper 128 and driver 118.

[0031] refer to Figure 1D The components of each receiver 140 are further described, and the components of each receiver 140 may include an optical amplifier (OA) 142, a polarization separator 144, a separator 146, a polarization / phase controller (PC) 148, a tunable phase shifter 150, a dispersion manager 152, a saturable absorber (SA) 154, a driver 155, a circulator 156, and an output component 158. In some embodiments, the components of the receiver 140 may be formed as ICs on a common semiconductor substrate.

[0032] OA 142 boosts the signal received from transmitter 110. In some embodiments, OA 142 may be coupled to fiber optic cable 170. In some embodiments, OA 142 may be connected to a WDM demultiplexer as further described below. In some embodiments, OA 142 may be a quantum dot semiconductor optical amplifier with low power consumption and minimal crosstalk between different wavelengths. In some embodiments, driver 145 may power OA 142.

[0033] OA 142 (λ) 1OTDM+CLOCKThe output of the signal (λ) is fed to the polarization separator 144, which will receive the signal (λ). 1OTDM+CLOCK The signal is divided into orthogonal transverse modes. A data mode (such as TM or TE as defined in the transmitter) is transmitted on data branch 141, and a clock mode (such as TM or TE as defined in the receiver) is transmitted on clock recovery branch 143. In some embodiments, polarization separator 144 divides the received signal unequally between the two modes. Non-limiting examples of division ratios include 90 / 10 and 80 / 20. In some embodiments, polarization separator 144 divides the received signal equally between the two modes.

[0034] Figure 1E This illustrates the combined OTDM signal (denoted here as λ) segmented within data branch 141. 1OTDM ), the recovery clock and phase-shift clock of clock branch 143 (denoted as λ here) 1-CLOCK , λ 1-CLOCK SHIFT ) and the recovered modulation (phase shift) channel (denoted as λ here). 1S1-MOD , λ 1S2-MOD，SHIFT (Illustrative signal amplitude diagram)

[0035] In data branch 141, splitter 146-1 divides the OTDM according to the number of channels time-division multiplexed by transmitter 110. Therefore, each branch of data branch 141 carries λ 1OTDM Similarly, in clock branch 143, splitter 146-2 divides the clock signal λ according to the number of channels time-division multiplexed by transmitter 110. 1-CLOCK As described above, for simplicity, two OTDM channels and their corresponding two clock channels are shown, but it should be understood that multiple channels can be demultiplexed.

[0036] In some embodiments, the polarization / phase controller (PC) 148 may be configured to match polarization and correct phase mismatch. Exemplarily, multiple PCs 148-1…148-4 are provided, each on a separate signal or clock branch. Tunable phase shifters 150-1 and 150-2 shift the phase of the clock channel such that clock pulses are timed to coincide with the interleaved channel of the OTDM signal in the data branch 141. Each dispersion manager (DM) 152 may correct dispersion in the optical channel that has affected the data and / or clock signals. Exemplarily, multiple DMs 152-1…152-4 are provided, each on a separate branch. DM 152 may also introduce pre-correction for dispersion introduced by SA 154. In some embodiments, DM 152 may include a chirped Bragg grating controlled by temperature controller 153. In some embodiments, driver 155 may power the respective SA 154.

[0037] Each output of clock branch 143 (represented here as λ1-) CLOCK and λ1- CLOCK SHIFT The data is fed to the corresponding circulator 156 in the data branch 141. Exemplarily, two circulators 156-1, 156-2, two SAs 154-1, 154-2, and two drivers 155-1, 155-2 are all shown corresponding to two multiplexed data channels. In some embodiments, circulator 156 may be a non-reciprocating, unidirectional, three-port circulator. Figure 1D In the diagram, circulator 156 is shown in a clockwise direction, but it should be understood that the direction adopted will be functional. In use, the clock input cycles to SA 154. In some embodiments, each SA 154 can be any of a quantum well (QW) semiconductor SA, a quantum dot SA, or a bulk semiconductor SA.

[0038] The clock pulse will saturate the SA 154, forcing it to become transparent, thereby "releasing" or "transmitting" the currently OTDM interleaved channel pulses through the SA 154 corresponding to the pulse period. Therefore, λ1- CLOCK and λ1- CLOCK SHIFT SA 154-1 and SA 154-2 are saturated at different time periods, each corresponding to a separate OTDM channel, thereby releasing the current OTDM channel pulse through SA 154. When the clock signal is between pulses (low clock signal), SA 154 is not saturated, thus blocking other OTDM channels. In some embodiments, each SA 154-1 or 154-2 provides an electrical output for each recovered clock 159-1 or 159-2.

[0039] The released OTDM pulses will enter circulator 156 and will be circulated to output components (OC) 158. Each OC 158 includes those components necessary to convert the released optical channel back into electrical data signal 102. Exemplarily, two OCs 158-1 and 158-2 corresponding to two multiplexed data channels are shown. OC 158 may include one or more of a photodiode (PD) or PD array for photoelectric conversion, a transimpedance amplifier (TIA), a DAC, and / or a limiting amplifier (LA).

[0040] In receiver 140, controller 160 can monitor and control all components and provide automatic adjustment of adjustable components such as phase shifter 150, OA 142, drivers 145, 155, and DM 152. In some embodiments, controller 160 monitors the performance of transceiver 108 based on one or more of parameters such as bit error rate, data throughput, frame loss, jitter, and then performs adjustments to adjustable components (in both transmitter 110 and receiver 140) to optimize transceiver 108 performance.

[0041] like Figure 1F As shown, in some embodiments, multiple systems 100-1, 100-2 to 100-X (where X = N / 2) can be provided in parallel, each system 100 operating on a separate pair of fiber optic cables 170-1 and 170-2. As further shown, each of the systems 100 can provide up to four channels of OTDM in each direction (102, 104). In some embodiments, more than four channels can be provided. Each of the systems 100-1, 100-2, and 100-X can be operated using a pulsed laser 112 having the same wavelength or different wavelengths or combinations of wavelengths.

[0042] like Figure 1G As shown, in some embodiments, multiple systems 100-1 to 100-X can be configured in parallel with wavelength division multiplexing (WDM) multiplexers 172-1 and 174-2 and demultiplexers 172-2 and 174-1, each multiplexer 172-1 and 174-2 operating on its respective single fiber optic cable 170-1 and 170-2. For WDM operation, each of systems 100-1, 100-2...100-N uses a corresponding pulsed laser 112 with a different wavelength. Figure 1G As further shown, each of the systems 100 can provide up to four channels of OTDM in each direction (102, 104). In some embodiments, more than four channels can be provided.

[0043] Figures 2A-2F An optical system for bidirectional data transmission over full-duplex optical fiber is illustrated according to some embodiments. For example... Figure 2A As shown, the optical transmission system 200 includes transceivers 208-1 and 208-2. Each transceiver 208 includes an optical transmitter 210, an optical receiver 240, a coupling assembly 209, and a controller 260.

[0044] Transmitter 210-1 communicates with receiver 240-2 via full-duplex optical cable 270 to transmit data signal 102 using a first wavelength (λ1), and transmitter 210-2 communicates with receiver 240-1 via full-duplex optical cable 270 to transmit data signal 104 using a second wavelength (λ2). In some embodiments, each of the transceivers 208 is provided as an IC on a shared semiconductor substrate.

[0045] Data signals 102 and 104 are electrical data signals. In some embodiments, data signals 102 and 104 are digital signals, and the laser pulse repetition rate is equal to or greater than the digital signal rate. In some embodiments, data signals 102 and 104 are analog electrical signals, and the laser pulse repetition rate is equal to or greater than the Nyquist frequency of the analog electrical signal. In some embodiments, data signals 102 and 104 are a combination of digital and analog signals. For simplicity, Figures 2A-2F The transmission of two channels in each transmission direction (data signals 102-1 and 102-2 and data signals 104-1 and 104-2) is shown, but it should be understood that the system 200 can transmit more than two channels. In some embodiments, 2-16 data signals per wavelength are supported.

[0046] Each controller 260 is a computing device as defined herein. Controller 260-1 communicates with transmitter 210-1 and receiver 240-1, and controller 260-2 communicates with transmitter 210-2 and receiver 240-2 to control each of transceivers 208-1 and 208-2 for operation of system 200, as further described below. In some embodiments, each of coupling components 209-1 and 209-2 communicates with its corresponding controller 260-1 and 260-2.

[0047] refer to Figure 2B The components of each transmitter 210 are further described, including a pulsed laser 112, a splitter 214, a 3dB splitter 116, a driver 118, an EO modulator 120, a tunable phase shifter 122, a 3dB coupler 124, and a pulse shaper 228. In some embodiments, the components of the transmitter 210 are formed on a common semiconductor as an IC. Components with the same reference numerals in the transmitter 110 are identical components and provide the same function in the transmitter 210, and therefore will not be described further.

[0048] Splitter 214 divides the pulsed laser signal into a data branch 213 for OTDM signal transmission and a clock branch 211 for clock transmission. In some embodiments, splitter 214 divides the pulsed laser signal intensity unequally between the two branches. Non-limiting examples of division ratios include 90 / 10 and 80 / 20. In some embodiments, splitter 214 divides the pulsed laser signal equally between the two branches.

[0049] In data branch 213, transmitter 212 provides OTDM for multiple data signals 102 (or 104). For simplicity, two data signals 102-1 and 102-2 are shown, but it should be understood that multiple data signals can be supported. Data branch 213 functions the same as system 100 and forms the OTDM output of data branch 233 with a pulse rate of R × (number of channels) (denoted as λ). 1 OTDM ).

[0050] In some embodiments, the pulse shaper 228-1 shapes and equalizes the pulse. 1 OTDM The pulse height and shape. In some embodiments, the pulse shaper 228-2 shapes and equalizes the pulse height and shape. 1-CLOCK The pulse height. In some implementations, pulse shaping can be achieved using filter banks. In some embodiments, pulse shaping can be achieved using nested unbalanced MZIs or ring resonators, or a combination of MZIs and ring resonators.

[0051] like Figure 2C As shown, the output of transmitter 210 is fed into coupling assembly 209. Each coupling assembly 209 includes a circulator 230 and a coupler 232. Pulse shaper 228-1 shapes λ... 1 OTDM The pulse is fed to the optical circulator 230-1, and the pulse shaper 288-2 will... 1 CLOCK The feed is sent to the optical circulator 230-2. In some embodiments, the circulator 230 may be a non-reciprocating, unidirectional, three-port circulator. Figure 2C In the diagram, the circulator 230 is shown in a clockwise direction, but it should be understood that the direction adopted will be functional.

[0052] One of the ports of circulator 230 is connected to coupler 232. Coupler 232-1 will output (Tx)λ 1 OTDM The first optical fiber coupled to cable 270, coupler 232-2 will output λ1- CLOCK A second optical fiber is coupled to fiber optic cable 270. Input (Rx) clock and OTDM signal λ. 2 OTDM and λ 2- CLOCKThe cable 270 exits from the coupler 232 and is guided by the circulator 230 to the outlet of the circulator 230, which is coupled to the input of the "same-side" receiver 240.

[0053] In transmitter 210, controller 160 can monitor and control all components and provide automatic adjustment of adjustable components such as phase shifter 122, pulse shaper 228 and driver 118.

[0054] refer to Figure 2D The components of each receiver 140 are further described, and each receiver 140 may include an optical amplifier (OA) 242, a splitter 146, a polarization / phase controller (PC) 148, a tunable phase shifter 150, a dispersion manager 152, a saturable absorber 154, a driver 155, a circulator 156, and an output component 158. In some embodiments, the components of receiver 240 may be formed on a common semiconductor as an IC. Components with the same reference numerals in receiver 140 are identical components and provide the same function in receiver 240, and therefore will not be described again.

[0055] OA 242-1 boosts the OTDM signal received from transmitter 210. OA 242-2 boosts the clock signal received from transmitter 210. Both OA 242s can be coupled to fiber optic cable 270 via coupling component 209. In some embodiments, OA 242 can be connected to a WDM demultiplexer as further described below. In some embodiments, OA 242 can be a quantum dot semiconductor optical amplifier with low power consumption and minimal crosstalk between different wavelengths. In some embodiments, driver 245 can power OA 242.

[0056] The output of OA 242-1 is fed to data branch 241, and the output of OA 242-2 is transmitted on clock branch 243. The function and operation of data branch 241 are the same as those of data branch 141 as described above, and the function and operation of clock branch 243 are the same as those of clock branch 143 as described above.

[0057] In receiver 240, controller 260 can monitor and control all components and provide automatic adjustment of adjustable components such as phase shifter 150, OA 242, driver 155, and DM 152. In some embodiments, controller 260 monitors the performance of transceiver 208 based on one or more of parameters such as bit error rate, data throughput, frame loss, jitter, and then performs adjustments to adjustable components (in both transmitter 210 and receiver 240) to optimize transceiver 208 performance.

[0058] like Figure 2EAs shown, in some embodiments, multiple systems 200-1, 200-2 to 200-X (where X = N / 2) can be provided in parallel, each operating on a separate full-duplex fiber optic cable 270-1, 270-2…270-X. As further shown, each system 200 can provide up to four channels of OTDM in each direction (102, 104). In some embodiments, more than four channels can be provided. Each of the systems 200-1, 200-2…200-X can be operated using a pulsed laser 112 having the same wavelength or different wavelengths or combinations of wavelengths.

[0059] like Figure 2F As shown, in some embodiments, multiple systems 200 and dual WDM multiplexers 272-1 and 272-2 and demultiplexers 274-1 and 274-2 operating on full-duplex fiber optic cables 270 can be provided in parallel. For simplicity, in Figure 2F Only one transmission direction is shown. OTDM signals are transmitted using WDM pairs 272-1 and 274-1, and clock signals are transmitted using WDM pairs 272-2 and 274-2. In some embodiments, one OA 242 is positioned before demultiplexer 274-1, and one OA 242 is positioned before demultiplexer 274-2. For WDM operation, each of systems 200-1, 200-2…200-X uses a pulsed laser 112 with a different wavelength. As further shown, each system 200 can provide up to four channels of OTDM. In some embodiments, more than four channels can be provided.

[0060] In the claims or description of this application, unless otherwise stated, adjectives (such as “substantially” and “about”) that modify one or more features of the embodiments of the invention are understood to mean that the condition or feature is defined within an acceptable tolerance range for operation of the embodiments.

[0061] Implementation of the methods and systems of this disclosure may involve manually, automatically, or in combination thereof, performing or completing certain selected tasks or steps. Furthermore, the actual instruments and devices according to preferred embodiments of the methods and systems of this disclosure can implement several selected steps via hardware (HW) or software (SW) on any operating system with any firmware, or via a combination thereof. For example, as hardware, the selected steps of this disclosure can be implemented as chips or circuits. As software or algorithms, the selected steps of this disclosure can be implemented as multiple software instructions executed by a computer using any suitable operating system. In any case, the selected steps of the methods and systems of this disclosure can be described as being executed by a data processor, such as a computing platform for executing multiple instructions.

[0062] Although this disclosure is described with respect to computing devices or computers, it should be noted that, optionally, any device having a data processor and the ability to execute one or more instructions can be described as a computing device, including, but not limited to, any type of personal computer (PC), server, distributed server, main control unit, virtual server, cloud computing platform, cellular phone, IP phone, smartphone, smartwatch, or PDA (personal digital assistant). Any two or more such devices communicating with each other may optionally form a "network" or "computer network".

[0063] It should be understood that when a claim or specification refers to an element “a, an”, such reference should not be interpreted as meaning that there is only one such element. In the specification and claims of this application, each verb “comprising,” “including,” and “having,” and its conjugates, are used to indicate that the object of the verb is not necessarily a complete list of the components, elements, or parts of the subject of the verb.

[0064] While this disclosure describes a limited number of embodiments, it should be understood that many variations, modifications, and other applications can be made to such embodiments. This disclosure is to be understood not to be limited to the specific embodiments described herein, but only to the scope of the appended claims.

Claims

1. A method comprising: Provides an optical transmitter with a pulsed laser, an optical receiver with a clock branch and a data branch including multiple saturable absorbers (SAs), and a polarization separator; The pulsed laser outputs a pulsed laser signal; The pulsed laser signal is modulated based on multiple data signals to form multiple modulated optical data signals; The multiple modulated optical data signals are optically time-division multiplexed to obtain multiplexed optical data signals; The pulsed laser signal is divided into a data branch and a clock branch by the polarization separator, so as to transmit the multiplexed optical data signal through the data branch and transmit optical clock signals through the clock branches respectively. The clock branch is configured to recover and phase-shift the optical clock signal into a plurality of phase-shifted recovered optical clock signals. Each of the plurality of saturable absorbers (SAs) optically communicates with one of the plurality of phase-shifted recovered optical clock signals. Each of the plurality of saturable absorbers (SAs) is configured to receive the multiplexed optical data signal and demultiplex one of the plurality of modulated optical data signals according to a corresponding optical clock signal from the plurality of phase-shift recovered optical clock signals.

2. The method according to claim 1, wherein, The transmission of the multiplexed optical data signal and the optical clock signal includes transmitting the multiplexed optical data signal and the optical clock signal in an orthogonal lateral mode over a single-mode optical fiber cable.

3. The method according to claim 1, wherein, The transmission of the multiplexed optical data signal and the optical clock signal includes transmitting the multiplexed optical data signal and the optical clock signal on separate cables within a full-duplex optical fiber cable.

4. The method according to claim 1, wherein, It also includes saturating a corresponding one of the plurality of saturable absorbers (SAs), thereby causing the corresponding one of the plurality of saturable absorbers (SAs) to release a pulse from one of the plurality of modulated optical data signals.

5. The method according to claim 1, wherein, It also includes extracting the optical clock signal into the optical clock signal recovered from the plurality of phase shifts.

6. The method according to claim 1, wherein, It also includes correcting the dispersion associated with each of the plurality of modulated optical data signals and the plurality of phase-shifted recovered optical clock signals.

7. The method according to claim 1, wherein, It also includes extracting the plurality of data signals from each of the plurality of modulated optical data signals.

8. The method according to claim 1, wherein, The modulation of the pulsed laser signal includes modulation using pulse amplitude modulation (PAM) or quadrature amplitude modulation (QAM).

9. The method according to claim 1, wherein, The pulsed laser is selected from the group consisting of bulk lasers, quantum well lasers, quantum dot lasers, semiconductor mode-locked lasers, and mode-locked integrated external cavity surface-emitting lasers.

10. The method according to claim 1, wherein, The pulsed laser has a pulse repetition rate between 5 GHz and 100 GHz.

11. The method according to claim 1, wherein, The optical receiver includes an optical amplifier (OA).

12. The method according to claim 11, wherein, The optical amplifier OA is a quantum dot semiconductor optical amplifier.

13. The method according to claim 1, wherein, The multiple data signals include 2-16 data channels.

14. The method according to claim 1, wherein, The plurality of data signals include digital signals and / or analog signals.

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