Method and apparatus for wavelength locking of optical wavelength division multiplexing microring modulator

Abstract

Several examples described herein provide control of the output modulation amplitude of an optoelectronic device. In one example, a method includes transmitting a data pattern to an optical modulator device. The method also includes identifying the optical modulation amplitude corresponding to a plurality of heater control values ​​of a heater thermally coupled to the optical modulator device, based on the corresponding photodiode current value identified while transmitting the data pattern. The method also includes determining the maximum optical modulation amplitude of the optical modulator device based on a plurality of optical modulation amplitudes corresponding to the plurality of heater control values, as identified. The method also includes controlling the heater at least in part on a determined maximum optical modulation amplitude modified by scaling the maximum photodiode current value.

Description

[Technical Field]

[0001] Examples of the present disclosure generally relate to controlling the output modulation amplitude of optoelectronic devices, for example, to methods and apparatus for wavelength locking of wavelength division multiplexing microring modulators.

[0002] This invention was made with the support of the U.S. Government under contract number HR0011-19-3-0004, awarded by the Defense Advanced Research Projects Agency. The U.S. Government has certain rights in this invention. [Background technology]

[0003] The slowing of Moore's Law and the increasing demand for bandwidth in modern high-speed communications necessitate new technologies and innovative techniques in circuit design to meet current challenges in data centers, supercomputers, and other applications. Integrated high-speed silicon photonic devices such as ring modulators, cascaded ring resonators, and Zehnder interferometers possess the characteristics to meet this high-bandwidth requirement due to their high energy efficiency and suitability for use in high-density wavelength division multiplexing (WDM) systems. However, such integrated high-speed silicon photonic devices are highly sensitive to process and temperature fluctuations, which can lead to performance failures. For example, sensitivity of the resonant wavelength due to process fluctuations and temperature drift results in transmission losses of the desired optical signal amplitude. For these reasons at least, improved techniques for maximizing the output modulation amplitude in optoelectronic devices are desired. [Overview of the Initiative]

[0004] Some examples described herein provide methods and apparatus for controlling the output modulation amplitude of optoelectronic devices, for example, for wavelength locking of wavelength division multiplexing microring modulators.

[0005] An example of the present disclosure is a method for operating an optoelectronic device. The method includes transmitting a data pattern to an optical modulator device of the optoelectronic device. The method also includes identifying an optical modulation amplitude corresponding to a plurality of heater control values ​​of a heater thermally coupled to the optical modulator device, at least in part on a corresponding photodiode current value identified while transmitting the data pattern. The method also includes determining a maximum optical modulation amplitude of the optical modulator device, at least in part on a plurality of optical modulation amplitudes of a31 corresponding to the plurality of heater control values, as identified. The method also includes controlling the heater at least in part on a determined maximum optical modulation amplitude modified according to a scaling value.

[0006] Another example of the present disclosure is an optoelectronic device. The optoelectronic device includes an optical modulator device, a heater thermally coupled to the optical modulator device, a photodiode associated with the optical modulator device, and a control circuit coupled to the heater and the photodiode. The control circuit transmits a data pattern to the optical modulator device. The control circuit is also for identifying the optical modulation amplitude corresponding to a heater control value, for each of a plurality of heater control values ​​of the heater, at least in part on the corresponding photodiode current value identified while transmitting the data pattern. The control circuit is also for determining the maximum optical modulation amplitude of the optical modulator device, at least in part on the plurality of optical modulation amplitudes corresponding to the plurality of heater control values. The control circuit is also for controlling the heater, at least in part on the determined maximum optical modulation amplitude modified according to a scaling value.

[0007] Another example of the present disclosure is an integrated circuit device. The integrated circuit device includes a communication interface for coupling the integrated circuit device with an optical modulator device, a heater, and a photodiode. The integrated circuit device also includes a control circuit coupled with the communication interface. The control circuit transmits a data pattern to the optical modulator device via the communication interface. The control circuit is also for identifying the optical modulation amplitude corresponding to a heater control value, for each of a plurality of heater control values ​​of the heater, based at least in part on the corresponding photodiode current value identified while transmitting the data pattern. The control circuit is also for determining the maximum optical modulation amplitude of the optical modulator device, based at least in part on a plurality of optical modulation amplitudes corresponding to a plurality of heater control values. The control circuit is also for controlling the heater via the communication interface, at least in part on the determined maximum optical modulation amplitude modified according to a scaling value.

[0008] These and other embodiments may be understood by referring to the following "Modes for Carrying Out the Invention". [Brief explanation of the drawing]

[0009] More detailed explanations of the features listed above, which are briefly summarized above, can be provided by referring to exemplary implementations, some of which are illustrated in the attached drawings. However, it should be noted that the attached drawings illustrate only typical exemplary implementations and should therefore not be considered limiting in scope. [Figure 1] This is a block diagram illustrating an example of a photonic communication system. [Figure 2] This is a block diagram illustrating an example of an optoelectronic device. [Figure 3] This is a block diagram illustrating an example of an optoelectronic device. [Figure 4] This is a flowchart illustrating a method for operating an optoelectronic device, based on several examples. [Figure 5]This is a flowchart illustrating a method for operating an optoelectronic device, based on several examples. [Figure 6] This is a flowchart illustrating a method for operating an optoelectronic device, based on several examples.

[0010] For ease of understanding, the same reference numerals are used to indicate identical elements common to the drawings, where possible. Elements of one embodiment are intended to be usefully incorporated into other embodiments. [Modes for carrying out the invention]

[0011] Some examples described herein provide methods and apparatus for controlling the output modulation amplitude of optoelectronic devices, for example, for wavelength locking of wavelength division multiplexing micro-ring modulators (MRMs).

[0012] Integrated high-speed silicon photonic devices are highly sensitive to process and temperature fluctuations, which can lead to performance failures. For example, the sensitivity of resonant wavelengths due to process fluctuations and temperature drift results in transmission losses of the desired optical signal amplitude in photonic or optoelectronic devices, including those housing optical modulation devices. Improved techniques for maximizing the output modulation amplitude in optoelectronic devices are desired.

[0013] Methods and apparatus for controlling the output modulation amplitude of optoelectronic devices are disclosed. In one or more embodiments, a temperature tracking technique is disclosed, and a control circuit is used to determine the maximum optical modulation amplitude and then to control a set of heaters for a set of optical modulator devices, each heater associated with one of the optical modulator devices. In some embodiments, the control circuit operates to find the maximum optical modulation amplitude of the optoelectronic devices. The maximum current of the photodiode is determined and then scaled based on a scaling value (coefficient, ratio). The maximum optical modulation amplitude value is then determined based on the scaled maximum current. In some embodiments, the scaling value is predetermined or configured for the optoelectronic devices. The heaters associated with the optoelectronic devices are then controlled during operation (mission mode) according to the scaled maximum optical modulation amplitude value.

[0014] The embodiments described herein offer advantages over existing techniques. One advantage is that the methods and apparatus described herein have a relatively smaller footprint and load than current approaches (e.g., sample-and-hold techniques). Another advantage is the implementation for providing optical transceivers operating at high data rates of approximately 56 gigabits per second or more. Another advantage is that process variations and temperature drifts that may result in transmission losses of the desired optical signal amplitude are compensated for, and the techniques described herein may be relatively less sensitive to heat, process, and input power than existing techniques. Another advantage is improved accuracy in controlling the resonant wavelength of the optical modulator device, regardless of the temperature and optical power variations experienced by the optical modulator device.

[0015] Various features are described below with reference to the drawings. Note that the drawings may be drawn to scale or not, and elements of similar structure or function are represented throughout the drawings by like reference numerals. Note that the drawings are only intended to facilitate the description of the features. They are not intended as an exhaustive description of the claimed invention or as limiting the scope of the claimed invention. Additionally, the illustrated examples need not have all of the aspects or advantages shown. Aspects or advantages described in connection with a particular embodiment are not necessarily limited to that embodiment and may be implemented in any other embodiment, whether or not so illustrated or explicitly described as such.

[0016] FIG. 1 is a block diagram showing a photonic communication system 100 according to an example. The photonic communication system 100 includes a laser source 110, a deinterleaver 120, a set of optical modulator blocks 130, an interleaver 140, a deinterleaver 150, and a set of optical demodulator blocks 160.

[0017] The laser source 110 generates a carrier 115 (carrier signal), for example, 4, 8, 16, or 32 carriers. Each carrier is associated with a specific wavelength (λ), and may be denoted as λn for a particular carrier, where n = 1, 2, 3,.... The carriers may additionally or alternatively be identified by their frequency (e.g., in gigahertz (GHz)). In one or more embodiments, the carriers have a regular wavelength or frequency separation (e.g., each carrier is separated from the next carrier by 100 GHz).

[0018] The deinterleaver 120 separates the carrier wave 115 into two or more sets of carrier waves 125. In one or more embodiments, the deinterleaver 120 separates the carrier wave 115 into two sets of carrier waves 125. In an example where the carrier wave 115 includes 16 individual carrier waves, each set of carrier waves can include 8 carrier waves. For example, if the carrier wave 115 includes 16 individual carrier waves each separated by 100 GHz, the first set of carrier waves 125 can include 8 carrier waves each separated by 200 GHz, and the second set of carrier waves 125 can include another 8 carrier waves each separated by 200 GHz. In one or more embodiments, the deinterleaver 120 is a Mach-Zehnder interferometer-based (MZI-based) deinterleaver.

[0019] The set 130 of optical modulator blocks receives two or more sets of carrier waves 125. Each optical modulator block 131 of the set 130 of optical modulator blocks is configured to operate with one of the carrier waves 115 generated by the laser source 110. For example, if there are 32 carrier waves in the carrier wave 115, the set 130 of optical modulator blocks includes 32 optical modulator blocks 131.

[0020] Each optical modulator block 131 includes an optical modulator device 138 thermally coupled to a heater 137, a drop port 132 optically coupled to the optical modulator device 138 and a photodiode 133, a driver 135 for providing a drive signal 134 to the optical modulator device 138, and a digital signal source 136 for providing a digital signal used to drive the optical modulator device 138. The digital signal source 136 provides a signal (e.g., data) used to modulate one of the carrier waves 115 associated with the optical modulator block 131, whereby following the modulation of the carrier wave by the optical modulator block 131, the carrier wave optically transports the signal provided by the digital signal source 136. Thus, the set 130 of optical modulator blocks modulates the carrier wave 115 using a set of signals, and each carrier wave transports one of the signals of the set of signals, collectively transporting a WDM signal.

[0021] In one or more embodiments, the optical modulator block 131 is divided into a photonic circuit 170 and an electrical circuit 180. For example, in some embodiments, the photonic circuit 170 is at least a part of one or more photonic integrated circuits, and the electrical circuit 180 is at least a part of an electrical integrated circuit. In other embodiments, the photonic circuit 170 and the electrical circuit 180 are different parts of a single integrated circuit, or different integrated circuits of a single integrated circuit system or assembly.

[0022] Each optical modulator block 131 is communicatively coupled to a control circuit 190, which in some embodiments may be or may be referred to as a controller. In one or more embodiments, the control circuit 190 is located in the same place as the electrical circuit 180 (e.g., on the same integrated circuit or within the same integrated system or assembly). In one or more embodiments, the control circuit 190 is separate from the electrical circuit 180 (e.g., on a different integrated circuit, on a different integrated system or assembly, or on a different integrated circuit but within the same integrated system or assembly). In one or more embodiments, the control circuit 190 includes a communication interface 195 for transmitting or receiving signals to or from one or more blocks or circuits of the photonic communication system 100, as further described herein.

[0023] Following the set of optical modulator blocks 130, two or more sets of carrier waves 125 are received by an interleaver 140, which couples the two or more sets of carrier waves 125 into a single WDM signal 145. In one or more embodiments, the carriers of the single WDM signal 145 have regular wavelength or frequency separation (e.g., each carrier is separated from the next carrier by only 100 GHz). In one or more embodiments, the WDM signal 145 is carried by either on-chip or off-chip (e.g., inter-chip or inter-assembly) waveguides. In some embodiments, the WDM signal 145 is carried by an on-chip waveguide of a photonic integrated circuit, e.g., an on-chip waveguide of a photonic integrated circuit including a photonic circuit 170. In one or more embodiments, the interleaver 140 is a Mach-Zehnder interferometer-based (MZI-based) interleaver.

[0024] The WDM signal 145 is received by a deinterleaver 150 which separates the WDM signal 145 into a set of two or more modulated carrier waves 165. A set of optical demodulator blocks 160 demodulates two or more sets of modulated carrier waves to extract the signal modulated on the carrier wave in the set of optical modulator blocks 130.

[0025] As further described herein, one or more embodiments may be implemented in a photonic communication system 100 that includes circuits (devices including optoelectronic devices) and algorithms (methods, processes, actions, or sets of actions) that increase or maximize a ring modulator output optical signal (e.g., output optical signals for one or more optical modulator blocks 131) by controlling its temperature (e.g., via a heater 137) and locking it to a maximum optical modulation amplitude (OMA) for each transmitter lane of a WDM optical link (e.g., WDM signal 145) (e.g., each carrier of carrier 115). Each example of one or more embodiments may be implemented to provide an optical transceiver operating at a high data rate of, for example, about 56 gigabits per second or more. In one or more examples, the laser source 110, which is an external laser source in one or more embodiments, generates 16 carrier waves, each having a wavelength λn that resonates with the corresponding resource wavelength (e.g., MRM resonant wavelength) of the optical modulator device, for example, in the case of a 16λ laser source, the optical modulator device 138 of the optical modulator block 131, which enables the transmission and reception of approximately 1 terabyte or more of data.

[0026] In one or more embodiments, the resonant frequency of the optical modulator device (e.g., the MRM resonant frequency) depends on (e.g., is highly sensitive to) process and temperature variations. Sensitivity of the resonant wavelength due to process variations and temperature drift can result in transmission losses of the desired optical signal amplitude. For example, a resonant wavelength shift due to temperature variations can result in dramatically different transmit eye diagrams. One or more embodiments described herein avoid variations in optical amplitude due to sensitivity to heat, process, and input power, and enhance their ability to be used in practical applications by enabling, for example, determination and control (e.g., precise control) of the resonant wavelength of the optical modulator device regardless of the temperature and optical power variations experienced by the optical modulator device.

[0027] According to one or more temperature tracking techniques, the maximum optical modulation amplitude (OMA) is calculated using sample-and-hold logic to integrate optical power when transmitting different data patterns. While this approach can work, it also has drawbacks. Firstly, transmitting data patterns (e.g., static signals such as 1111... or 0000...) to calculate the maximum OMA during calibration can cause self-heating of the optical modulator device. Such self-heating can cause a different temperature for the device containing the optical modulator device during calibration (e.g., a photonic integrated circuit) than for the device during actual data transmission mode (e.g., "mission mode"). Secondly, sample-and-hold circuit-based OMA calculations rely on several analog blocks such as comparators, capacitors, reference digital-to-analog converters (DACs), OTAs, and offset cancellation circuits, which inherently have large area usage. Thirdly, conventional techniques, including sample-and-hold architectures, are sensitive to the input power range. When the laser power is low, OMA detection can be difficult due to the low optical power, which does not provide enough time to charge the parasitic sampling capacitance. On the other hand, when the optical power is relatively high, a large programmable capacitance is required to handle the large optical power. Since there is no mechanism to know the optical power in a given optical modulator device (e.g., in an MRM), selecting an appropriate sampling capacitance is difficult.

[0028] According to the techniques described herein, the maximum OMA can be determined at least partially by calibrating the DC behavior of the optical modulator device 138 (e.g., a ring modulator) and setting the resonant wavelength to a value at which the modulation efficiency is determined to be the maximum OMA, near the maximum OMA, or close to the maximum OMA.

[0029] The drop port power at the drop port (e.g., drop port 132) of the optical modulator device (e.g., optical modulator device 138) can be expressed by Equation 1.

[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037] Figure 2 is a block diagram showing an example of an optoelectronic device 200. In one or more embodiments, the optoelectronic device 200 is an example of at least a part of a photonic communication system 100. In one or more embodiments, the optoelectronic device 200 includes a photonic circuit 170 and an electrical circuit 250, the electrical circuit including both an electrical circuit 180 and a control circuit 190. In one or more embodiments, one or more of the photonic circuit 170, the electrical circuit 180, or the control circuit 190 are located in the same place (e.g., on the same integrated circuit with the same integration system or assembly, or within the same integration system or assembly). In other embodiments, one or more of the photonic circuit 170, the electrical circuit 180, or the control circuit 190 are separate (e.g., on different integrated circuits, on different integration systems or assemblies, or on different integrated circuits but within the same integration system or assembly). In one or more embodiments, the control circuit 190 includes a communication interface 195 for transmitting or receiving signals, including a drive signal 134, to or from one or more blocks or circuits of the optoelectronic device 200, as further described herein.

[0038] In one or more embodiments, the control circuit 190 of the optoelectronic device 200 includes a processor 210, a memory 220, and a support circuit 230. In some embodiments, the control circuit 190 is or includes a DSP. The control circuit 190, which includes one or more of the processor 210, the memory 220, or the support circuit 230, can perform one or more operations of the methods described herein.

[0039] The processor 210 (e.g., a DSP) can operate together with memory 220 (e.g., non-volatile memory) and support circuitry 230. The support circuitry 230 (e.g., one or more caches, clock circuits, input / output subsystems, power supplies (e.g., current sources, voltage sources), digital-to-analog converters (DACs) (e.g., current DACs (IDACs), voltage DACs (VDACs)), analog-to-digital converters (ADCs), voltage-controlled oscillators (VCOs), multiplexers (MUXs), demultiplexers (deMUXs), flip-flops (FFs), etc., and combinations thereof) is conventionally coupled to the processor 210 and to various other components of the optoelectronic device 200 or the photonic communication system 100.

[0040] In one or more embodiments, the processor 210 is any circuit sufficient to implement the features (processes, operations, methods) described herein, such as an application-specific integrated circuit (ASIC), a DSP, or a field-programmable gate array (FPGA) (e.g., an FPGA programmed according to register transfer levels (RTL) that implement the features described herein). In some embodiments, the processor 210 is one of any form of general-purpose computer processor used with optical communication equipment, such as a programmable logic controller (PLC) for controlling system components and subprocessors.

[0041] The memory 220 coupled to the processor 210 is non-temporary and is typically one or more readily available memories such as random access memory (RAM), read-only memory (ROM), a floppy disk drive, a hard disk, or any other form of local or remote digital storage.

[0042] In one or more embodiments, the memory 220 is in the form of a computer-readable storage medium (e.g., non-volatile memory) containing instructions that, when executed by the processor 210, facilitate the operation of the optoelectronic device 200 or the photonic communication system 100. The instructions in the memory 220 are in the form of a program product, such as a program that implements the method of the Disclosure (e.g., middleware application, device software application, etc.). The program code may conform to one of several different programming languages. In one example, the Disclosure may be implemented as a program product stored in a computer-readable storage medium for use with a computer system. The program of the program product defines the functionality of the embodiments (including the method of the Disclosure herein).

[0043] Exemplary computer-readable storage media include, but are not limited to, (i) non-writable storage media on which information is permanently stored (e.g., read-only memory devices in a computer, such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips, or any type of solid-state non-volatile semiconductor memory), and (ii) writable storage media on which modifiable information is stored (e.g., floppy disks in a diskette drive or hard disk drive, or any type of solid-state random-access semiconductor memory). Such computer-readable storage media constitute embodiments of the present disclosure when they carry computer-readable instructions that direct the functions of the methods described herein.

[0044] Figure 3 is a block diagram showing an example of an optoelectronic device 300. In one or more embodiments, the optoelectronic device 300 is an example of at least a part of a photonic communication system 100, an optoelectronic device 200, or both. In one or more embodiments, the optoelectronic device 300 includes a photonic circuit 170 and an electrical circuit 250, the electrical circuit including both an electrical circuit 180 and a control circuit 190. In one or more embodiments, one or more of the photonic circuit 170, the electrical circuit 180, or the control circuit 190 are located in the same place (e.g., on the same integrated circuit with the same integration system or assembly, or within the same integration system or assembly). In other embodiments, one or more of the photonic circuit 170, the electrical circuit 180, or the control circuit 190 are separate (e.g., on different integrated circuits, on different integration systems or assemblies, or on different integrated circuits but within the same integration system or assembly). In one or more embodiments, the control circuit 190 includes a communication interface 195 for transmitting or receiving signals, such as those further described herein, including a reference voltage control signal 324, a TIA IDAC code 326, and / or a heater code 335, to or from one or more blocks or circuits of the optoelectronic device 300.

[0045] The optoelectronic device 300 is a top-level diagram of the temperature tracking system. In one or more embodiments, the electrical circuit 250 includes a transimpedance control circuit 320, a heater control circuit 330, a capacitor flip-flop (CapFF) 340, a clock source 345 (e.g., an uncorrelated voltage-controlled oscillator (VCO) clock), a VDAC 350, a transimpedance amplifier (TIA) and an IDAC 360, and a heater DAC 370.

[0046] The photonic circuit 170 (e.g., a photonic integrated circuit (PIC)) is an optical block in which temperature tracking and wavelength locking are performed. The electrical circuit 250 (e.g., an electrical integrated circuit (EIC)) includes an exemplary design that can wavelength lock an optical signal (e.g., a carrier wave among carrier waves 125) and track temperature fluctuations. The heater 137 (e.g., a heater resistor Rheat ) warms the optical modulator device 138 (e.g., MRM filter) to control the temperature, and thus the wavelength, of the optical modulator device 138. In one or more embodiments, the output DC current of the photodiode 133 (e.g., I PD ) is a function of the wavelength offset, transmitter modulation power, and laser input power of the optical modulator device 138. The output DC current of the photodiode 133 (e.g., I PD ) varies the TIA DC output 294 (e.g., output voltage) of the TIA and IDAC360 (this is V pd ). The digital TIA DC loop including the transimpedance control circuit 320, and the TIA and IDAC360, which is clocked according to the clock source 345 and the system clock 322 using the output of the VDAC 350 that provides the reference voltage 355 (V cm ) based on the CapFF 340 (e.g., an 8-bit value specifying the reference voltage control signal 324 (V cm ) from the control circuit 190), measures the photodiode voltage (V pd ) of the photodiode 133 (TIA DC output 294), adjusts the TIA IDAC code 326 (TIA_DAC_CTRL) to cancel I pd and stabilize the TIA DC output voltage to the reference voltage V cm . The TIA IDAC code reflects the value of I PD , and thus the optical power converted by the photodiode 133 and the center wavelength of the optical modulator device 138 (e.g., MRM filter).

[0047] I PDBased on the magnitude of (TIA_DAC_CTRL) versus heater code 335 (e.g., Therm_DAC_CTRL), the control circuit 190 (e.g., heater control circuit 330, sometimes called heater RTL or heater DSP in some examples) determines (calculates, calculates) the maximum power. The control circuit 190 then parks (sets, controls) the wavelength of the optical modulator device 138 to a predetermined ratio K, as further described above. The ratio K is sometimes referred to herein as the scaling value or scaling ratio. In one or more embodiments, the control circuit 190 monitors the wavelength by TIA IDAC code 326 (e.g., TIA_DAC_CTRL) and adjusts heater code 335 (e.g., Therm_DAC_CTRL) to lock the wavelength of the photonic circuit 170 when the filter wavelength deviates due to temperature drift.

[0048] In one or more embodiments, the optoelectronic device 300 includes a temperature controller circuit for maximizing the optical amplitude of the optical modulator device 138 (e.g., MRM). The TIA DC loop adjusts the TIA IDAC value to control the photodiode output DC current I PD This cancels the TIA DC voltage and the reference voltage V cm Make it equal to PD output DC current I PD This is the wavelength offset f of the filter. osIt is a function of the optical input power and the transmitter data pattern. During calibration, the control circuit 190 (e.g., TX heater DSP) transmits a data pattern (e.g., a DC balanced data pattern such as 101010...) to avoid self-heating of the optical modulator device 138. The output current 296 from the heater DAC 370 (based on heater code 335 (e.g., Therm_DAC_CTRL)) controls the temperature of the optical modulator device 138 (e.g., ring filter) by controlling the heat (e.g., thermal energy) provided by the heater 137, and thus controls the center wavelength of the optical modulator device 138. The control circuit 190 sweeps the heater code 335 (e.g., Therm_DAC_CTRL) and observes the TIA IDAC code 326 (e.g., TIA_DAC_CTRL). The heater control circuit 330 selects a heater code 335, for example at the start of link operation, such that the filter wavelength of the optical modulator device 138 aligns with, or substantially aligns with, a desired incoming wavelength. The selected heater code 335 is at the drop port (e.g., drop port 132) of the optical modulator device 138, with the maximum drop port power

[0049]

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[0050]

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[0051] The operation of the photonic communication system 100, the optoelectronic device 200, and / or the optoelectronic device 300 includes the following operations:

[0052] In one or more embodiments, the first operation is that the TIA DC loop (e.g., a loop including at least CapFF340, transimpedance control circuit 320, and TIA and IDAC360) adjusts the TIA IDAC code 326 to V the TIA DC output 294. pd Including biasing, TIA IDAC code 326 represents DC power at drop port 132.

[0053] In one or more embodiments, the second operation includes identifying the corresponding TIA IDAC code 326 for each heater code 335 (e.g., Therm_DAC_CTRL), which may also be called a thermal code, (e.g., by the control circuit 190, or by its components such as the processor 210, the transimpedance control circuit 320, and / or the heater control circuit 330). In one or more embodiments, the control circuit 190 continues the search for the maximum TIA IDAC code 326 for values ​​of heater code 335 within a given search range.

[0054] In one or more embodiments, the third operation includes the control circuit 190 identifying (finding) the filter center frequency of a filter (e.g., an optical modulator device 138) based on a maximum TIA IDAC code 326 that represents (corresponds to) the maximum optical power at the drop port 132.

[0055] In one or more embodiments, the fourth operation includes the control circuit 190 determining (calculating) a value of the TIA IDAC code 326 which is the ratio of the maximum value of the TIA IDAC code 326 (TIA_DAC_CTRL) to the subsequent heater code 335 (e.g., Therm_DAC_CTRL).

[0056] In one or more embodiments, the fifth operation includes performing continuous temperature tracking and wavelength locking (e.g., by the control circuit 190) by adjusting the heater code 335 (e.g., the heater DAC code).

[0057] Figure 4 is a flowchart of Method 400 for operating an optoelectronic device according to several embodiments. In one or more embodiments, the operation described with reference to Method 400 is performed by one or more components of the photonic communication system 100, optoelectronic device 200, or optoelectronic device 300, such as a control circuit 190, a processor 210, a memory 220, a support circuit 230, a transimpedance control circuit 320, and / or a heater control circuit 330.

[0058] In one or more embodiments, the method 400 (process, algorithm, operation) includes a set of operations (phases). For example, these operations may include at least heater search range initialization and OMA search.

[0059] In operation 405, the optoelectronic device is in an idle or sleep state.

[0060] In operation 410, the heater (including, for example, the heater control circuit 330) is enabled. In one or more embodiments, the heater IDAC (e.g., TIA and IDAC 360) has a relatively large adjustment range. Therefore, the control circuit 190 (heater control circuit 330) limits the initial heater IDAC search range to about 200 GHz in order to find the filter peak, for example, based on the IDAC value versus the heater code 335 (e.g., Therm_DAC_CTRL). In some examples, the filter center falls outside this range, and therefore the filter may lock onto the next wavelength. As a result, all filters are shifted by one channel (carrier), potentially consuming additional power (e.g., up to about 5 milliwatts per channel).

[0061] Therefore, the control circuit 190 first detects whether the first TIA IDAC code in the search range exceeds the threshold. If it does, the control circuit 190 reduces the upper and lower limits of the search range until the control circuit 190 finds that the TIA IDAC code is below the threshold. In some examples, this ensures that the initial point of the search range is to the left of the center, and therefore the filter center can always be covered.

[0062] During filter initialization, heater code 335 (e.g., Therm_DAC_CTRL) is swept from end to start (e.g., prog_heater_end and prog_heater_start) or from start to end (e.g., prog_heater_start and prog_heater_end). If all TIA IDACs are below the minimum threshold, the channel missing flag is declared. Otherwise, filter calibration begins.

[0063] In operation 415, a data pattern is transmitted to drive the optical modulator device 138. In some embodiments, the control circuit 190 drives the optical modulator device 138 with a driver 135 according to a data pattern 485. In some embodiments, the data pattern 485 is a DC balanced data pattern (10101...) that can prevent a self-heating effect on the optical modulator device 138. That is, by transmitting a DC balanced data pattern, the optical modulator block 131, including the optical modulator device 138, can have the same or approximately the same temperature when calibration is being performed as when actual data transmission is taking place (e.g., during mission mode).

[0064] In operation 420, the control circuit 190 determines whether there are any further heater codes 335 (e.g., Therm_DAC_CTRL) within the range of the heater code 335 to be searched. If there are still heater codes 335 to be searched (e.g., at the start of the search), method 400 proceeds to operation 425. If there are no further heater codes 335 within the search range, method 400 proceeds to operation 450.

[0065] In operation 425, the control circuit 190 (for example, using the heater control circuit 330) sets the heater code 335 (for example, Therm_DAC_CTRL), and the control circuit 190 also retrieves the corresponding digital representation IDAC for the heater code 335 (for example, using the transimpedance control circuit 320).

[0066] In operation 430, the control circuit 190 increments the heater code 335 (for example, using the heater control circuit 330), thereby causing the heater DAC 370 to supply current to the heater 137 according to different values, thereby changing the temperature of the heater 137 and, consequently, the temperature of the optical modulator device 138 in the optical modulator block 131.

[0067] In one or more embodiments, the control circuit 190 may loop through operations 420, 425, and 430 until the control circuit 190 determines that the end of the search range for heater code 335 has been reached in operation 420. For example, the loop may continue until the minimum heater setting (prog_heater_start) is reached, for example, if the maximum heater setting is the starting point (prog_heater_end).

[0068] In operation 440, the control circuit 190 (e.g., using the heater control circuit 330) determines (discover, calculate, identify) the corresponding value of the TIA IDAC code 326 (e.g., TIA_DAC_CTRL) for the maximum optical power (e.g., IDAC_MAX), and the control circuit 190 (e.g., the TX DSP) determines (discover, calculate, identify, look up) a new value of the TIA IDAC code 326 (e.g., TIA_DAC_CTRL) by multiplying the value of the TIA IDAC code 326 corresponding to the maximum optical power (e.g., IDAC_MAX) by a predetermined value (configured value, set value, calculated value, parameter). In one or more embodiments, the predetermined value is a programmable ratio K, as further described herein.

[0069] In operation 445, the control circuit 190 (for example, using the heater control circuit 330) determines (finds, calculates, identifies, and looks up) the heater code 335 (e.g., thermal DAC value) corresponding to the new value of the TIA IDAC code 326 from operation 440.

[0070] In operation 450, the control circuit 190 causes the optoelectronic device to enter normal data transmission (mission) mode. For example, once the maximum OMA is obtained and the heater is incremented, the control circuit 190 asserts a calibration complete signal so that the transmitter can be in normal data transmission (mission) mode. In one or more embodiments, asserting the calibration complete signal includes the control circuit 190 signaling, via an enable signal 390 (e.g., Cal_Enable), to cause the electrical circuit 180 to choose to acquire data 380 (e.g., data pattern 385) for the driver 135 to use to supply a drive signal 134 to the optical modulator device 138.

[0071] Figure 5 is a flowchart of a method 500 for operating an optoelectronic device according to several embodiments. In one or more embodiments, the optoelectronic device is an example of at least a portion of one optical modulator block 131 from a set of optical modulator blocks 130 and a control circuit 190.

[0072] In operation 505, the method includes transmitting a data pattern to the optical modulator device of the optoelectronic device.

[0073] In operation 510, the method includes identifying the optical modulation amplitude corresponding to each of a plurality of heater control values ​​of a heater thermally coupled to an optical modulator device, at least in part, based on the corresponding photodiode current value identified while transmitting a data pattern.

[0074] In operation 515, the method includes determining the maximum optical modulation amplitude of an optical modulator device based at least in part on a plurality of optical modulation amplitudes corresponding to a plurality of heater control values, in accordance with the identification of these values.

[0075] In operation 520, the method includes controlling the heater at least in part on a determined maximum optical modulation amplitude modified according to a scaling value.

[0076] In one or more embodiments, the data pattern is a series of alternating "0" bits and "1" bits.

[0077] In one or more embodiments, the method further includes identifying that a first heater control value associated with a first photodiode current value within a range of heater control values ​​exceeds a threshold. The method then includes adjusting the range to determine a plurality of heater control values, at least in part, based on the range of heater control values ​​that exceed the threshold.

[0078] In one or more embodiments, the method further includes determining the maximum optical modulation amplitude of each optical modulator device in a plurality of optical modulator devices, which is associated with a corresponding heater among a plurality of heaters. The method then includes controlling each of the plurality of heaters according to the determined maximum optical modulation amplitude, which has been modified according to the scaling value of the optical modulator device corresponding to the heater.

[0079] In one or more embodiments, the scaling value of an optical modulator device is one of several scaling values ​​associated with multiple optical modulator devices. In other embodiments, the scaling value of an optical modulator device is the same scaling value used for all of the multiple optical modulator devices.

[0080] In one or more embodiments, the optical modulator device is a silicon microring modulator. In one or more embodiments, the heater is controlled by a digital signal processor.

[0081] In one or more embodiments, two or more of the operations 505 or 510 are performed substantially in parallel (simultaneously).

[0082] Figure 6 is a flowchart of a method 600 for operating an optoelectronic device according to several embodiments. In one or more embodiments, the optoelectronic device is an example of at least a portion of one optical modulator block 131 from a set of optical modulator blocks 130 and a control circuit 190.

[0083] In operation 605, the method includes adjusting a range to determine a plurality of heater control values ​​based at least in part on a range of heater control values ​​that exceed a threshold. In one or more embodiments, the method includes identifying that a first heater control value associated with a first photodiode current value within a range of heater control values ​​exceeds a threshold, and then adjusting a range to determine a plurality of heater control values ​​based at least in part on a range of heater control values ​​that exceed a threshold.

[0084] In operation 610, the method includes transmitting a data pattern to the optical modulator device of the optoelectronic device.

[0085] In operation 615, the method includes identifying the optical modulation amplitude corresponding to each of a plurality of heater control values ​​of a heater thermally coupled to an optical modulator device, at least in part, based on the corresponding photodiode current value identified while transmitting a data pattern.

[0086] In operation 620, the method includes determining the maximum optical modulation amplitude of an optical modulator device based at least in part on a plurality of optical modulation amplitudes corresponding to a plurality of heater control values, as identified.

[0087] In operation 625, the method includes controlling the heater at least in part on a determined maximum optical modulation amplitude modified according to a scaling value.

[0088] In one or more embodiments, two or more of operations 610 or 615 are performed substantially concurrently. In one or more embodiments, operation 605 is performed after or substantially concurrently with at least one or more portions of operations 610, 615, 620, or 625.

[0089] In one or more embodiments, one or more operations of method 500 may be combined with one or more operations of method 600.

[0090] The above disclosure may be represented by one or more of the following non-limiting embodiments.

[0091] Example 1: A method for operating an optoelectronic device, comprising: transmitting a data pattern to an optical modulator device of the optoelectronic device; identifying an optical modulation amplitude corresponding to a plurality of heater control values ​​of a heater thermally coupled to the optical modulator device, at least in part on a corresponding photodiode current value identified while transmitting the data pattern; determining a maximum optical modulation amplitude of the optical modulator device, at least in part on a plurality of optical modulation amplitudes corresponding to the plurality of heater control values, in accordance with the identification; and controlling the heater, at least in part on the determined maximum optical modulation amplitude modified according to a scaling value.

[0092] Example 2: The method according to Example 1, wherein the data pattern includes a series of alternating "0" bits and "1" bits.

[0093] Example 3: The method according to Example 1, further comprising identifying that a first heater control value associated with a first photodiode current value within a range of heater control values ​​exceeds a threshold, and adjusting the range to determine a plurality of heater control values ​​based at least partially on the range of heater control values ​​exceeding the threshold.

[0094] Example 4: The method according to Example 1, further comprising determining the maximum optical modulation amplitude of each optical modulator device in a plurality of optical modulator devices, each optical modulator device in a plurality of optical modulator devices, which is associated with a corresponding heater among a plurality of heaters, and controlling each heater of the plurality of heaters according to the determined maximum optical modulation amplitude, which has been modified according to the scaling value of the optical modulator device corresponding to the heater.

[0095] Example 5: The method according to Example 4, wherein the scaling value of the optical modulator device is one of several scaling values ​​associated with multiple optical modulator devices.

[0096] Example 6: The method according to Example 4, wherein the scaling value of the optical modulator device is the same scaling value used for all of the multiple optical modulator devices.

[0097] Example 7: The optical modulator device is the same as in Example 1, wherein the optical modulator device includes a silicon microring modulator.

[0098] Example 8: The method according to Example 1, wherein the heater is controlled by a digital signal processor.

[0099] Example 9: An optoelectronic device comprising: an optical modulator device; a heater thermally coupled to the optical modulator device; a photodiode associated with the optical modulator device; and a control circuit coupled to the heater and the photodiode, wherein the control circuit transmits a data pattern to the optical modulator device; for each of a plurality of heater control values ​​of the heater, identifies an optical modulation amplitude corresponding to the heater control value based at least in part on the corresponding photodiode current value identified while transmitting the data pattern; determines the maximum optical modulation amplitude of the optical modulator device based at least in part on the plurality of optical modulation amplitudes corresponding to the plurality of heater control values; and controls the heater at least in part on the determined maximum optical modulation amplitude modified according to a scaling value.

[0100] Example 10: The optoelectronic device according to Example 9, wherein the data pattern includes a series of alternating "0" bits and "1" bits.

[0101] Example 11: The optoelectronic device according to Example 9, wherein the control circuit further identifies when a first heater control value associated with a first photodiode current value within a range of heater control values ​​exceeds a threshold, and adjusts the range to determine a plurality of heater control values ​​based at least partially on the range of heater control values ​​exceeding the threshold.

[0102] Example 12: The optoelectronic device according to Example 9, further comprising a plurality of optical modulator devices coupled to a control circuit and a plurality of heaters, wherein each optical modulator device of the plurality of optical modulator devices is associated with a corresponding heater among the plurality of heaters, and the control circuit further determines the maximum optical modulation amplitude of each optical modulator device of the plurality of optical modulator devices and controls each heater of the plurality of heaters according to the determined maximum optical modulation amplitude modified according to the scaling value of the optical modulator device corresponding to the heater.

[0103] Example 13: The optoelectronic device according to Example 12, wherein the scaling value of the optical modulator device is one of several scaling values ​​associated with multiple optical modulator devices.

[0104] Example 14: The optoelectronic device described in Example 12, wherein the scaling value of the optical modulator device is the same scaling value used for all of the multiple optical modulator devices.

[0105] Example 15: An integrated circuit device comprising a communication interface for coupling the integrated circuit device with an optical modulator device, a heater, and a photodiode, and a control circuit coupled to the communication interface, wherein the control circuit transmits a data pattern to the optical modulator device via the communication interface, identifies an optical modulation amplitude corresponding to a plurality of heater control values ​​of the heater, at least in part based on a corresponding photodiode current value identified while transmitting the data pattern, determines a maximum optical modulation amplitude of the optical modulator device at least in part based on a plurality of optical modulation amplitudes corresponding to the plurality of heater control values, and controls the heater via the communication interface at least in part based on the determined maximum optical modulation amplitude modified according to a scaling value.

[0106] Example 16: The integrated circuit device according to Example 15, wherein the data pattern includes a series of alternating "0" bits and "1" bits.

[0107] Example 17: The integrated circuit device according to Example 15, wherein the control circuit further identifies when a first heater control value associated with a first photodiode current value within a range of heater control values ​​exceeds a threshold, and adjusts the range to determine a plurality of heater control values ​​based at least partially on the range of heater control values ​​that exceed the threshold.

[0108] Example 18: The integrated circuit device according to Example 15, further comprising a plurality of optical modulator devices coupled to a control circuit and a plurality of heaters, wherein each optical modulator device of the plurality of optical modulator devices is associated with a corresponding heater among the plurality of heaters, and the control circuit further determines the maximum optical modulation amplitude of each optical modulator device of the plurality of optical modulator devices and controls each heater of the plurality of heaters via a communication interface according to the determined maximum optical modulation amplitude modified according to the scaling value of the optical modulator device corresponding to the heater.

[0109] Example 19: The integrated circuit device according to Example 18, wherein the scaling value of the optical modulator device is one of several scaling values ​​associated with multiple optical modulator devices.

[0110] Example 20: The integrated circuit device described in Example 18, wherein the scaling value of the optical modulator device is the same scaling value used for all of the multiple optical modulator devices.

[0111] The above applies to specific examples, but other and further examples may be devised without departing from the basic scope, and the scope will be determined by the following "Claims".

Claims

1. A method for operating an optoelectronic device, Transmitting a data pattern to the optical modulator of the aforementioned optoelectronic device, For each of the multiple heater control values ​​of the heater thermally coupled to the optical modulator device, the optical modulation amplitude corresponding to the heater control value is identified, at least in part, based on the corresponding photodiode current value identified while the data pattern is being transmitted. In accordance with the above identification, the maximum optical modulation amplitude of the optical modulator device is determined at least partially based on a plurality of optical modulation amplitudes corresponding to the plurality of heater control values, A method comprising controlling the heater at least in part on the determined maximum optical modulation amplitude modified according to a scaling value.

2. Identifying that a first heater control value associated with a first photodiode current value within the range of heater control values ​​exceeds a threshold, The method according to claim 1, further comprising adjusting the range to determine the plurality of heater control values ​​based at least partially on the range of heater control values ​​that exceed the threshold.

3. For each optical modulator device of a plurality of optical modulator devices, which is associated with a corresponding heater among a plurality of heaters, the maximum optical modulation amplitude of the optical modulator device is determined. The method according to claim 1, further comprising controlling each of the plurality of heaters according to the determined maximum optical modulation amplitude, which is modified according to the scaling value of the optical modulator device corresponding to the heater.

4. The method according to claim 3, wherein the scaling value of the optical modulator device is one of a plurality of scaling values ​​associated with the plurality of optical modulator devices.

5. The method according to claim 3, wherein the scaling value of the optical modulator device is the same scaling value used for all of the plurality of optical modulator devices.

6. The method according to claim 1, wherein the optical modulator device includes a silicon microring modulator.

7. The method according to claim 1, wherein the heater is controlled by a digital signal processor.

8. Optoelectronic devices, Optical modulator device, A heater thermally coupled to the optical modulator device, A photodiode associated with the optical modulator device, The heater and the photodiode are coupled to a control circuit, and the control circuit is A data pattern is transmitted to the optical modulator device. For each of the multiple heater control values ​​of the heater, the optical modulation amplitude corresponding to the heater control value is identified, at least partially based on the corresponding photodiode current value identified while the data pattern is being transmitted. The maximum optical modulation amplitude of the optical modulator device is determined based at least partially on a plurality of optical modulation amplitudes corresponding to the plurality of heater control values. An optoelectronic device for controlling the heater based at least in part on the determined maximum optical modulation amplitude modified according to a scaling value.

9. Multiple optical modulators coupled to the control circuit, The optical modulator device further comprises a plurality of heaters, wherein each optical modulator device of the plurality of heaters is associated with a corresponding heater among the plurality of heaters. The aforementioned control circuit further For each of the above-mentioned plurality of optical modulator devices, the maximum optical modulation amplitude of the optical modulator device is determined. The optoelectronic device according to claim 8, for controlling each of the plurality of heaters according to the determined maximum optical modulation amplitude, which is modified according to the scaling value of the optical modulator device corresponding to the heater.

10. An integrated circuit device, A communication interface for coupling the aforementioned integrated circuit device with an optical modulator device, a heater, and a photodiode, The system comprises a control circuit coupled to the communication interface, and the control circuit is A data pattern is transmitted to the optical modulator device via the communication interface. For each of the multiple heater control values ​​of the heater, the optical modulation amplitude corresponding to the heater control value is identified, at least partially based on the corresponding photodiode current value identified while the data pattern is being transmitted. The maximum optical modulation amplitude of the optical modulator device is determined based at least partially on a plurality of optical modulation amplitudes corresponding to the plurality of heater control values. An integrated circuit device for controlling the heater via a communication interface, at least in part, based on the determined maximum optical modulation amplitude modified according to a scaling value.

11. The optoelectronic device according to claim 8 or the integrated circuit device according to claim 10, wherein the data pattern includes a series of alternating "0" bits and "1" bits.

12. The aforementioned control circuit further Identify that the first heater control value associated with the first photodiode current value within the range of heater control values ​​exceeds a threshold, The optoelectronic device according to claim 8 or the integrated circuit device according to claim 10, which adjusts the range to determine the plurality of heater control values ​​based at least partially on the range of the heater control value that exceeds the threshold.

13. Multiple optical modulators coupled to the control circuit, The optical modulator device further comprises a plurality of heaters, and each of the plurality of optical modulator devices is associated with a corresponding heater among the plurality of heaters. The aforementioned control circuit further For each of the above-mentioned plurality of optical modulator devices, the maximum optical modulation amplitude of the optical modulator device is determined. The integrated circuit device according to claim 10, for controlling each of the plurality of heaters via a communication interface according to the determined maximum optical modulation amplitude, which is modified according to the scaling value of the optical modulator device corresponding to the heater.

14. The optoelectronic device according to claim 9 or the integrated circuit device according to claim 13, wherein the scaling value of the optical modulator device is one of a plurality of scaling values ​​associated with the plurality of optical modulator devices.

15. The optoelectronic device according to claim 9 or the integrated circuit device according to claim 13, wherein the scaling value of the optical modulator device is the same scaling value used for all of the plurality of optical modulator devices.

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