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

Abstract

Some examples described herein provide for controlling an output modulation magnitude of an optoelectronic device. In an example, a method includes transmitting a data pattern to an optical modulator device. The method further includes, for each of a plurality of heater control values of a heater thermally coupled with the optical modulator device, identifying an optical modulation magnitude corresponding to the heater control value based on a corresponding photodiode current value identified in the transmission data mode. The method further includes determining a maximum optical modulation amplitude of the optical modulator device based on the plurality of optical modulation amplitudes corresponding to the plurality of heater control values in accordance with the identification. The method further includes controlling the heater based at least in part on the determined maximum optical modulation magnitude that has been modified according to the scaled maximum photodiode current value.

Description

Technical Field

[0001] Examples of this disclosure generally relate to controlling the output modulation amplitude of optoelectronic devices, such as 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 and under Agreement No. HR0011-19-3-0004 granted by the Defense Advanced Research Projects Agency (DARPA). The U.S. government enjoys certain rights to this invention. Background Technology

[0003] The ever-increasing bandwidth demands of modern high-speed communications, coupled with the slowing of Moore's Law, necessitate new and innovative technologies 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 Zengel interferometers, possess the characteristics to meet this high bandwidth requirement due to their energy efficiency and ability to be used in dense wavelength division multiplexing (WDM) systems. However, such integrated high-speed silicon photonic devices can be highly sensitive to process variations and temperature changes, leading to poor performance. For example, sensitivity to the resonant wavelength caused by process variations and temperature drift results in transmission losses for the desired optical signal amplitude. For at least these reasons, improved techniques for maximizing the output modulation amplitude in optoelectronic devices are desired. Summary of the Invention

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

[0005] An example of this disclosure is a method of operating an optoelectronic device. The method includes transmitting a data pattern to an optical modulator device of the optoelectronic device. The method further includes identifying an optical modulation amplitude corresponding to each of a plurality of heater control values ​​for a heater thermally coupled to the optical modulator device, at least in part based on a corresponding photodiode current value identified during the transmission of the data pattern. The method further includes determining a maximum optical modulation amplitude of the optical modulator device based on the identification, at least in part based on the plurality of optical modulation amplitudes corresponding to the plurality of heater control values. The method further includes controlling the heater at least in part based on the determined maximum optical modulation amplitude, which has been modified according to a scaling value.

[0006] Another example of this 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 control circuitry coupled to the heater and the photodiode. The control circuitry is configured to transmit a data pattern to the optical modulator device. The control circuitry is further configured to identify an optical modulation amplitude corresponding to each of a plurality of heater control values ​​for the heater, at least in part based on a corresponding photodiode current value identified during the transmission of the data pattern. The control circuitry is further configured to determine a maximum optical modulation amplitude of the optical modulator device, at least in part based on the plurality of optical modulation amplitudes corresponding to the plurality of heater control values. The control circuitry is further configured to control the heater, at least in part based on the determined maximum optical modulation amplitude, which has been modified according to a scaling value.

[0007] Another example of this disclosure is an integrated circuit device. The integrated circuit device includes a communication interface for coupling the integrated circuit device to an optical modulator device, a heater, and a photodiode. The integrated circuit device also includes control circuitry coupled to the communication interface. The control circuitry is used to transmit a data pattern to the optical modulator device via the communication interface. The control circuitry is also used to identify an optical modulation amplitude corresponding to each of a plurality of heater control values ​​for the heater, at least in part based on a corresponding photodiode current value identified during the transmission of the data pattern. The control circuitry is also used to determine a maximum optical modulation amplitude of the optical modulator device, at least in part based on the plurality of optical modulation amplitudes corresponding to the plurality of heater control values. The control circuitry is also used to control the heater via the communication interface, at least in part based on the determined maximum optical modulation amplitude, which has been modified according to a scaling value.

[0008] These and other aspects can be understood by referring to the following detailed description. Attached Figure Description

[0009] To gain a more detailed understanding of the features described above, a more specific description of the brief summary can be obtained by referring to the exemplary embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only typical exemplary embodiments and should not be considered as limiting the scope of the description.

[0010] Figure 1 This is a block diagram depicting a photonic communication system based on an example.

[0011] Figure 2 It is a block diagram depicting an optoelectronic device based on the example.

[0012] Figure 3It is a block diagram depicting an optoelectronic device based on the example.

[0013] Figure 4 This is a flowchart illustrating methods for operating optoelectronic devices based on some examples.

[0014] Figure 5 This is a flowchart illustrating methods for operating optoelectronic devices based on some examples.

[0015] Figure 6 This is a flowchart illustrating methods for operating optoelectronic devices based on some examples.

[0016] For ease of understanding, the same reference numerals are used where possible to denote common elements in the accompanying figures. It is conceivable that elements of one example can be advantageously incorporated into other examples. Detailed Implementation

[0017] Some examples described herein provide methods and apparatus for controlling the output modulation amplitude of optoelectronic devices, such as wavelength locking for wavelength division multiplexing microring modulators (MRMs).

[0018] Integrated high-speed silicon photonic devices can be highly sensitive to process and temperature variations, leading to poor performance. For example, sensitivity to resonant wavelengths caused by process variations and temperature drift results in transmission losses of the desired optical signal amplitude in photonic or optoelectronic devices, including those containing optical modulation devices. Improved techniques are desired for maximizing the output modulation amplitude in optoelectronic devices.

[0019] Methods and apparatus for controlling the output modulation amplitude of optoelectronic devices are disclosed. In one or more embodiments, temperature tracking techniques are disclosed, wherein control circuitry is used to determine a maximum optical modulation amplitude and then control a set of heaters for a group of optical modulator devices, each heater being associated with one of the optical modulator devices. In some embodiments, the control circuitry operates to find the maximum optical modulation amplitude of the optoelectronic device. The maximum current of the photodiode is found and then scaled based on a scaling value (factor, ratio). The maximum optical modulation amplitude is then determined based on the scaled maximum current. In some embodiments, the scaling value is predetermined or configured for the optoelectronic device. The heaters associated with the optoelectronic device are then controlled according to the scaled maximum optical modulation amplitude during operation (task mode).

[0020] The embodiments described herein offer advantages over existing technologies. One advantage includes that the methods and apparatus described herein have a relatively smaller footprint and load than current methods (e.g., through sample-and-hold techniques). Another advantage includes providing specific implementations of optical transceivers operating at high data rates (e.g., approximately 56 gigabits per second or higher). Another advantage includes compensating for process variations and temperature drift that can cause transmission losses to the desired optical signal amplitude, and the techniques described herein can have relatively lower thermal sensitivity, process sensitivity, and input power sensitivity than existing technologies. Another advantage is improved accuracy in controlling the resonant wavelength of the optical modulator device, for example, regardless of temperature variations and optical power variations experienced by the optical modulator device.

[0021] Various features are described below with reference to the accompanying drawings. It should be noted that the drawings may be drawn to scale or not, and elements with similar structures or functions are indicated by similar reference numerals in all drawings. It should be noted that the drawings are intended only to facilitate the description of features. They are not intended as an exhaustive description of the claimed invention or as a limitation on the scope of the claimed invention. Furthermore, the illustrated examples need not possess all aspects or advantages shown. Aspects or advantages described in conjunction with a particular example are not necessarily limited to that example and may be practiced in any other example even if not so shown or so explicitly described.

[0022] Figure 1 This is a block diagram depicting 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.

[0023] Laser source 110 generates carrier waves 115 (carrier signals), such as 4, 8, 16, or 32 carrier waves. Each carrier wave is associated with a specific wavelength (λ), which may represent λn for a given carrier wave, where n = 1, 2, 3, ... . The carrier waves may additionally or alternatively be identified by their frequency (e.g., in gigahertz (GHz) units). In one or more embodiments, the carrier waves have regular wavelength or frequency spacing (e.g., each carrier wave is spaced 100 GHz from the next).

[0024] Deinterleaving 120 splits carrier 115 into two or more groups of carriers 125. In one or more embodiments, deinterleaving 120 splits carrier 115 into two groups of carriers 125. In an example where carrier 115 comprises sixteen individual carriers, each group of carriers may comprise eight carriers. For example, in the case where carrier 115 comprises sixteen individual carriers each separated by 100 GHz, the first group of carriers 125 may comprise eight carriers each separated by 200 GHz, and the second group of carriers 125 may comprise another eight carriers each separated by 200 GHz. In one or more embodiments, deinterleaving 120 is a Mach-Zehnder interferometer-based (MZI) deinterleaving device.

[0025] The group of optical modulator blocks 130 receives two or more groups of carriers 125. Each optical modulator block 131 in the group of optical modulator blocks 130 is configured to operate using one of the carriers 115 generated by the laser source 110. For example, if there are thirty-two carriers in the carriers 115, then the group of optical modulator blocks 130 contains thirty-two optical modulator blocks 131.

[0026] Each optical modulator block 131 includes an optical modulator device 138 thermally coupled to a heater 137, a tap port 132 optically coupled to the optical modulator device 138 and a photodiode 133, a driver 135 providing a drive signal 134 to the optical modulator device 138, and a digital signal source 136 providing a digital signal for driving the optical modulator device 138. The digital signal source 136 provides a signal (e.g., data) for modulating one of the carriers 115 associated with the optical modulator block 131, such that after the optical modulator block 131 modulates the carrier, the carrier will optically carry the signal provided by the digital signal source 136. Therefore, this group of optical modulator blocks 130 will modulate the carriers 115 with a set of signals, each carrier carrying one signal from that set, collectively referred to as WDM signals.

[0027] In one or more embodiments, the optical modulator block 131 is divided into photonic circuit 170 and circuit 180. For example, in some embodiments, photonic circuit 170 is at least a portion of one or more photonic integrated circuits, and circuit 180 is at least a portion of an electronic integrated circuit. In other embodiments, photonic circuit 170 and circuit 180 are different portions of a single integrated circuit or different integrated circuits of a single integrated circuit system or component.

[0028] Each optical modulator block 131 is communicatively coupled to control circuitry 190, which in some embodiments may be or be referred to as a controller. In one or more embodiments, control circuitry 190 is located in the same location as circuitry 180 (e.g., on the same integrated circuit, or within the same integrated system or component). In one or more embodiments, control circuitry 190 is separate from circuitry 180 (e.g., on different integrated circuits, on different integrated systems or components, or on different integrated circuits but within the same integrated system or component). In one or more embodiments, control circuitry 190 includes a communication interface 195 for sending or receiving signals as further described herein to or from one or more blocks or circuits of photonic communication system 100.

[0029] Following the set of optical modulator blocks 130, two or more sets of carriers 125 are received at an interleaver 140, which combines the two or more sets of carriers 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 spacing (e.g., each carrier is spaced 100 GHz from the next). In one or more embodiments, the WDM signal 145 is carried by a waveguide, either on-chip or off-chip (e.g., between chips or components). In some embodiments, the WDM signal 145 is carried by an on-chip waveguide of a photonic integrated circuit, such as an on-chip waveguide of a photonic integrated circuit containing photonic circuitry 170. In one or more embodiments, the interleaver 140 is a Mach-Zehnder interferometer-based (MZI-based) interleaver.

[0030] The WDM signal 145 is received at a deinterleaver 150, which splits the WDM signal 145 into two or more modulated carriers 165. A set of optical demodulator blocks 160 demodulates the two or more modulated carriers to extract the signal modulated onto the carrier at the set of optical demodulator blocks 130.

[0031] As further described herein, one or more embodiments may be implemented in photonic communication system 100, including circuitry (devices, including optoelectronic devices) and algorithms (methods, procedures, operations, or sets of operations) that increase or maximize the optical modulation amplitude (OMA) of the ring modulator output optical signal (e.g., the output optical signal of one or more optical modulator blocks 131) by controlling the temperature of the ring modulator output optical signal (e.g., via heater 137) and locking it to the maximum optical modulation amplitude (OMA) of each transmitter channel (e.g., each carrier of carrier 115) of the WDM optical link (e.g., WDM signal 145). Examples of one or more embodiments may be implemented as providing an optical transceiver operating at a high data rate (e.g., about 56 gigabits per second or higher). In one or more examples, laser source 110 (in one or more embodiments, an external laser source) generates sixteen carriers, each carrier having a wavelength λn that resonates with a corresponding resource wavelength (e.g., MRM resonant wavelength) of an optical modulator device (e.g., optical modulator device 138 of optical modulator block 131), which allows the transmission and reception of approximately one terabyte or more of data for a 16λ laser source.

[0032] In one or more embodiments, the resonant frequency of the optical modulator device (e.g., the MRM resonant frequency) depends on process variations and temperature variations (e.g., it is highly sensitive to process and temperature variations). Sensitivity to the resonant wavelength due to process variations and temperature drift can lead to transmission losses in the desired optical signal amplitude. For example, a resonant wavelength shift due to temperature variations can result in significantly different transmission eye diagrams. One or more embodiments described herein avoid optical amplitude fluctuations due to thermal, process, and input power sensitivity by allowing the determination and control (e.g., precise control) of the resonant wavelength of the optical modulator device, and increase its usability in practical applications, regardless of temperature and optical power variations experienced by the optical modulator device.

[0033] Based on one or more temperature tracking techniques, sample-and-hold logic is used to calculate the maximum optical modulation amplitude (OMA) to integrate optical power when transmitting different data modes. While this method works, it has drawbacks. First, transmitting data modes (e.g., static signals such as 1111… or 0000…) during calibration to calculate the maximum OMA can lead to self-heating of the optical modulator device. This self-heating can cause the temperature of the device containing the optical modulator device (e.g., a photonic integrated circuit) to differ during calibration from the temperature of the device during actual data transmission modes (e.g., during “mission mode”). Second, OMA calculation based on sample-and-hold circuitry relies on several analog blocks, such as comparators, capacitors, reference digital-to-analog converters (DACs), over-the-air (OTA) converters, and offset cancellation circuitry, which are inherently large in terms of area usage. Third, existing techniques involving sample-and-hold architectures are sensitive to the range of input power. If the laser power is low, OMA detection can become difficult because the low optical power does not provide sufficient time to charge the parasitic sampling capacitor. On the other hand, if the optical power is relatively high, large programmable capacitors are required to handle the high optical power. Because there is no mechanism to know the optical power at a given optical modulator device (e.g., at the MRM), choosing an appropriate sampling capacitor is difficult.

[0034] According to the techniques described herein, the maximum OMA can be determined at least in part by calibrating the DC behavior of the optical modulator device 138 (e.g., a ring modulator) and setting the resonant wavelength to a value where the modulation efficiency is determined to be at, approximately or close to the maximum OMA.

[0035] The tap power at the tap port (e.g., tap port 132) of the optical modulator device (e.g., optical modulator device 138) can be represented by Equation 1: (1) in and ; This describes the coupling behavior between buses (e.g., buses transmitting the carrier of carrier 125) associated with a ring (e.g., optical modulator device 138). It is the photon lifetime in the ring. At resonance ( The peak power at the tap port is It can be shown that if the resonance of the ring (e.g., optical modulator device 138) causes the laser wavelength (e.g., from laser source 110) to be at the point of highest slope of the resonance curve, then the modulated OMA will be at its maximum. The point of maximum slope or maximum optimal modulation efficiency is at... At the location, and calculate the power of the tap port as This means that locking the DC power from the monitoring port (e.g., tap port 132) to ¾ of the peak power from the port sets the detuning to the position where the modulation efficiency is maximized. Therefore, to initiate locking, the ring transresonant is tuned and Extracted. As discussed further in this paper, the detection of peak power and locking of power from the peak is described. Methods and apparatus for generating DC power, wherein K is a predetermined (programmable, settable, configurable ratio, and in one or more embodiments may be set to ¾, for example, according to the calculations described above.)

[0036] Figure 2 This is a block diagram depicting an optoelectronic device 200 according to an example. In one or more embodiments, optoelectronic device 200 is an example of at least a portion of photonic communication system 100. In one or more embodiments, optoelectronic device 200 includes photonic circuitry 170 and circuitry 250, which includes both circuitry 180 and control circuitry 190. In one or more embodiments, one or more of photonic circuitry 170, circuitry 180, or control circuitry 190 are located in the same location (e.g., on the same integrated circuit, or within the same integrated system or component). In other embodiments, one or more of photonic circuitry 170, circuitry 180, or control circuitry 190 are separate (e.g., on different integrated circuits, on different integrated systems or components, or on different integrated circuits but within the same integrated system or component). In one or more embodiments, control circuitry 190 includes a communication interface 195 for sending or receiving signals as further described herein, including drive signal 134, to or from one or more blocks or circuits of optoelectronic device 200.

[0037] In one or more embodiments, the control circuitry 190 of the optoelectronic device 200 includes a processor 210, a memory 220, and support circuitry 230. In some embodiments, the control circuitry 190 is or includes a DSP. The control circuitry 190, including one or more of the processor 210, memory 220, or support circuitry 230, can perform one or more operations of the methods described herein.

[0038] Processor 210 (e.g., DSP) may operate together with memory 220 (e.g., non-volatile memory) and support circuitry 230. Support circuitry 230 (e.g., one or more caches, clock circuitry, 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), and combinations thereof) is conventionally coupled to processor 210 and to various other components of optoelectronic device 200 or photonic communication system 100.

[0039] In one or more embodiments, 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-level (RTL) for implementing the features described herein). In some embodiments, processor 210 is a computer processor among any form of general-purpose computer processor used in conjunction with optical communication equipment, such as a programmable logic controller (PLC) for controlling system components and subprocessors.

[0040] The memory 220 coupled to the processor 210 is non-transitory and is typically one or more readily available memories, such as random access memory (RAM), read-only memory (ROM), floppy disk drive, hard disk, or any other form of local or remote digital storage device.

[0041] In one or more embodiments, memory 220 is in the form of a computer-readable storage medium (e.g., non-volatile memory) containing instructions that, when executed by processor 210, facilitate the operation of optoelectronic device 200 or photonic communication system 100. The instructions in memory 220 are in the form of a program product, such as a program implementing the methods of this disclosure (e.g., middleware application, device software application, etc.). The program code may conform to any of a variety of different programming languages. In one example, this disclosure may be implemented as a program product stored on 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 methods described herein).

[0042] Exemplary computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer, such as CD-ROM discs readable by a CD-ROM drive, flash memory, ROM chips, or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., floppy disks or any type of solid-state random access semiconductor memory within a floppy disk drive or hard disk drive) on which modifiable information is stored. Such computer-readable storage media are embodiments of this disclosure when carrying computer-readable instructions that direct the function described herein.

[0043] Figure 3 This is a block diagram depicting an optoelectronic device 300 according to an example. In one or more embodiments, optoelectronic device 300 is an example of at least a portion of photonic communication system 100, optoelectronic device 200, or both. In one or more embodiments, optoelectronic device 300 includes photonic circuitry 170 and circuitry 250, which includes both circuitry 180 and control circuitry 190. In one or more embodiments, one or more of photonic circuitry 170, circuitry 180, or control circuitry 190 are located in the same location (e.g., on the same integrated circuit, or within the same integrated system or component). In other embodiments, one or more of photonic circuitry 170, circuitry 180, or control circuitry 190 are separate (e.g., on different integrated circuits, on different integrated systems or components, or on different integrated circuits but within the same integrated system or component). In one or more embodiments, the control circuitry 190 includes a communication interface 195 for sending or receiving signals as further described herein to one or more blocks or circuits of the optoelectronic device 300, including a reference voltage control signal 324, a TIA IDAC code 326, and / or a heater code 335.

[0044] Optoelectronic device 300 is the top-level diagram of the temperature tracking system. In one or more embodiments, circuit 250 includes transimpedance control circuit 320, heater control circuit 330, capacitor trigger (CapFF) 340, clock source 345 (e.g., uncorrelated voltage-controlled oscillator (VCO) clock), VDAC 350, transimpedance amplifier (TIA) and IDAC 360, and heater DAC 370.

[0045] Photonic circuit 170 (e.g., photonic integrated circuit (PIC)) is an optical block to which temperature tracking and wavelength locking are to be performed. Circuit 250 (e.g., electronic integrated circuit (EIC)) includes an exemplary design capable of wavelength-locking an optical signal (e.g., a carrier in carrier 125) and tracking temperature changes. Heater 137 (e.g., heater resistor) R 加热The optical modulator device 138 (e.g., an MRM filter) is heated to control the temperature of the optical modulator device 138, and thus the wavelength. In one or more embodiments, the output DC current of the photodiode 133 (e.g., I PD The output DC current of photodiode 133 is a function of the wavelength shift of optical modulator device 138, transmitter modulation power, and laser input power. I PD Change the TIA DC output 294 of the TIA and IDAC 360 (e.g., the output voltage), which is... V pd Includes a digital TIA DC loop of CapFF 340 (using the output of VDAC 350, which provides a reference voltage 355 based on reference voltage control signal 324). V cm (For example, from control circuit 190, such as 8-bit value specification) V cm ), and measures the photodiode voltage of photodiode 133 based on clock source 345 and system clock 322, transimpedance control circuit 320, and TIA and IDAC 360. V pd (TIA DC output 294), and adjust TIA IDAC code 326 (TIA_DAC_CTRL) to eliminate I pd This stabilizes the TIA DC output voltage at the reference voltage. V cm TIA IDAC code reflects I PD The value of , and thus reflects the optical power converted by photodiode 133 and the center wavelength of optical modulator device 138 (e.g., MRM filter).

[0046] based on I PDThe relationship between the amplitude of (TIA_DAC_CTRL) and heater code 335 (e.g., Therm_DAC_CTRL) determines (calculates, estimates) the maximum power by control circuitry 190 (e.g., heater control circuitry 330, which in some examples may also be or referred to as heater RTL or heater DSP). Control circuitry 190 then stops (sets, controls) the wavelength of optical modulator device 138 at a predetermined ratio K, as discussed further above. Ratio K may also be referred to herein as scaling value or scaling ratio. In one or more embodiments, control circuitry 190 monitors the wavelength via TIA IDAC code 326 (e.g., TIA_DAC_CTRL) and tunes heater code 335 (e.g., Therm_DAC_CTRL) to lock the wavelength of photonic circuitry 170 if the filter wavelength deviates due to temperature drift.

[0047] 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 eliminate the DC current output by the photodiode. I PD This makes the TIA DC voltage equal to the reference voltage. V cm PD output DC current I PD It is the wavelength shift of the filter. f os The optical input power is a function of the transmitter data mode. During calibration, control circuitry 190 (e.g., a TX heater DSP) sends a data mode (e.g., a DC balanced data mode, such as 101010…) to prevent self-heating of the optical modulator device 138. Output current 296 from heater DAC 370 (based on heater code 335 (e.g., Therm_DAC_CTRL)) controls the temperature of the optical modulator device 138 (e.g., a ring filter) by controlling the heat (e.g., thermal energy) provided by heater 137, and thus controls the center wavelength of the optical modulator device 138. Control circuitry 190 scans heater code 335 (e.g., Therm_DAC_CTRL) and observes TIA IDAC code 326 (e.g., TIA_DAC_CTRL). Heater control circuitry 330 selects heater code 335 such that the filter wavelength of the optical modulator device 138 is aligned or substantially aligned with the desired input wavelength, for example, at the start of link operation. The selected heater code 335 corresponds to the maximum downlink port power at the tap port (e.g., tap port 132) of the optical modulator device 138. The control circuit 190 (e.g., heater control circuit 330) then determines (calculates, estimates) the maximum OMA, which can be based on a given ratio, such as from this power. Subsequently (for example, after initial calibration is completed), heater control circuit 330 can monitor and calibrate wavelength drift of optical modulator device 138 due to temperature changes.

[0048] The operation of the photonic communication system 100, the optoelectronic device 200, and / or the optoelectronic device 300 includes the following operations.

[0049] In one or more embodiments, the first operation includes the TIA DC loop (e.g., including at least the CapFF 340, the transimpedance control circuit 320, and the loops of TIA and IDAC 360) biasing the TIA DC output 294 to the tuned TIA IDAC code 326. V pd Furthermore, TIA IDAC code 326 indicates the DC power at tap 132.

[0050] In one or more embodiments, the second operation includes, for each heater code 335 (e.g., Therm_DAC_CTRL) (which may also be referred to as a thermal code), identifying the corresponding TIA IDAC code 326 (e.g., via control circuitry 190 or components thereof, such as processor 210, transimpedance control circuitry 320, and / or heater control circuitry 330). In one or more embodiments, control circuitry 190 continues to search for the maximum TIA IDAC code 326 of the value of heater code 335 within a given search range.

[0051] In one or more embodiments, the third operation includes control circuitry 190 identifying (finding) the filter center frequency of a filter (e.g., optical modulator device 138) based on the maximum TIA IDAC code 326, which represents the maximum optical power at tap port 132.

[0052] In one or more embodiments, the fourth operation includes control circuitry 190 determining (calculating) a value for TIA IDAC code 326, which is the ratio of the maximum value of TIA IDAC code 326 (TIA_DAC_CTRL) to heater code 335 (e.g., Therm_DAC_CTRL).

[0053] In one or more embodiments, the fifth operation includes performing (e.g., via control circuitry 190) continuous temperature tracking and wavelength locking via tuning heater code 335 (e.g., heater DAC code).

[0054] Figure 4This is a flowchart of a method 400 for operating an optoelectronic device according to some examples. 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 control circuitry 190, processor 210, memory 220, support circuitry 230, transimpedance control circuitry 320, and / or heater control circuitry 330.

[0055] In one or more implementations, method 400 (process, algorithm, operation) includes multiple sets of operations (phases). For example, these operations may include at least heater search range initialization and OMA search. At operation 405, the optoelectronic device is in an idle or sleep state.

[0056] At operation 410, the heater is activated (e.g., including heater control circuitry 330). In one or more embodiments, the heater IDAC (e.g., TIA and IDAC 360) has a relatively large tuning range. Therefore, control circuitry 190 (heater control circuitry 330) limits the initial heater IDAC search range to approximately 200 GHz to find filter peaks, for example, based on IDAC values ​​and heater codes 335 (e.g., Therm_DAC_CTRL). In some examples, the filter center falls outside this range, so the filter can be locked to its next wavelength. Therefore, all filters are shifted by one channel (carrier) and in some cases consume additional power (e.g., up to approximately 5 milliwatts per channel).

[0057] Therefore, control circuit 190 first detects whether the TIA IDAC code at the beginning of the search range is higher than a threshold. If it is higher than the threshold, control circuit 190 reduces the upper and lower ends of the search range until control circuit 190 finds the TIA IDAC code to be lower than the threshold. In some examples, this ensures that the initial point of the search range is to the left of the center, so the center of the filter can always be covered.

[0058] During filter initialization, heater codes 335 (e.g., Therm_DAC_CTRL) are scanned 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 fall below the minimum threshold, a channel loss flag is declared. Otherwise, filter calibration begins.

[0059] At operation 415, a data pattern is transmitted to drive the optical modulator device 138. In some embodiments, control circuitry 190 causes the optical modulator device 138 to be driven by driver 135 according to data pattern 485. In some embodiments, data pattern 485 is a DC balanced data pattern (10101…) that prevents self-heating effects on the optical modulator device 138. That is, transmitting the DC balanced data pattern allows the optical modulator block 131, including the optical modulator device 138, to have the same or approximately the same temperature when calibration is performed as when actual data transmission occurs (e.g., during mission mode).

[0060] At operation 420, control circuit 190 determines whether there are more heater codes 335 (e.g., Therm_DAC_CTRL) within the range of heater codes 335 to be searched (e.g., Therm_DAC_CTRL). If there are more heater codes 335 to search (e.g., at the start of the search), method 400 proceeds to operation 425. If no more heater codes 335 are found within the search range, method 400 proceeds to operation 450.

[0061] At operation 425, control circuit 190 (e.g., using heater control circuit 330) sets heater code 335 (e.g., Therm_DAC_CTRL), and control circuit 190 (e.g., using transimpedance control circuit 320) searches for heater code 335 in the corresponding digital representation IDAC.

[0062] At operation 430, control circuit 190 (e.g., using heater control circuit 330) increments heater code 335, causing heater DAC 370 to supply current to heater 137 according to different values, thereby changing the temperature of heater 137 and thus changing the temperature of optical modulator device 138 of optical modulator block 131.

[0063] In one or more embodiments, control circuitry 190 may cycle through operations 420, 425, and 430 until control circuitry 190 determines at operation 420 that the end of the search range for heater code 335 has been reached. For example, the cycle may continue until the minimum heater setting (prog_heater_start) is reached, for example, where the maximum heater setting is the start point (prog_heater_end).

[0064] At operation 440, control circuit 190 (e.g., using heater control circuit 330) determines (finds, calculates, identifies) the corresponding value of TIA IDAC code 326 (e.g., TIA_DAC_CTRL) for the maximum optical power (e.g., IDAC_MAX). Control circuit 190 (e.g., TX DSP) determines (finds, calculates, identifies, looks up) the new value of TIA IDAC code 326 (e.g., TIA_DAC_CTRL) by multiplying the value of TIA IDAC code 326 corresponding to the maximum optical power (e.g., IDAC_MAX) by a predetermined value (configuration value, setting value, calculated value, parameter). In one or more embodiments, the predetermined value is a programmable ratio. K As discussed further in this article.

[0065] At operation 445, control circuit 190 (e.g., using heater control circuit 330) determines (finds, calculates, identifies, searches) heater code 335 (e.g., thermal DAC value) corresponding to the new value of TIA IDAC code 326 from operation 440.

[0066] At operation 450, control circuitry 190 puts the optoelectronic device into normal data transmission (task) mode. For example, once maximum OMA is achieved and the heater increments, control circuitry 190 asserts a calibration completion signal, allowing the transmitter to enter normal data transmission (task) mode. In one or more embodiments, asserting a calibration completion signal includes control circuitry 190 signaling circuitry 180 via enable signal 390 (e.g., Cal_Enable) to select to obtain data 380 (e.g., instead of data mode 385) for driver 135 to provide drive signal 134 to optical modulator device 138.

[0067] Figure 5 This is a flowchart of a method 500 for operating an optoelectronic device according to some examples. In one or more embodiments, the optoelectronic device is an example of at least a portion of an optical modulator block 130 and a control circuit 190 in a set of optical modulator blocks 131.

[0068] At operation 505, the method includes transmitting a data pattern to an optical modulator device of an optoelectronic device.

[0069] At operation 510, the method includes each of a plurality of heater control values ​​for a heater thermally coupled to the optical modulator device, wherein the optical modulation amplitude corresponding to the heater control value is identified at least in part based on the corresponding photodiode current value identified during the data transmission mode.

[0070] At operation 515, the method includes determining the maximum optical modulation amplitude of the optical modulator device based on an identifier that is at least partially based on a plurality of optical modulation amplitudes corresponding to a plurality of heater control values.

[0071] At operation 520, the method includes controlling the heater at least in part based on a determined maximum optical modulation amplitude that has been modified according to the scaling value.

[0072] In one or more implementations, the data pattern is a series of alternating "0" bits and "1" bits.

[0073] In one or more embodiments, the method further includes identifying a first heater control value associated with a first photodiode current value within a heater control value range that exceeds a threshold. The method then includes adjusting the range to determine a plurality of heater control values ​​based at least in part on the range of heater control values ​​exceeding the threshold.

[0074] In one or more embodiments, the method further includes determining, for each of a plurality of optical modulator devices, a maximum optical modulation amplitude associated with a corresponding heater among a plurality of heaters. The method then includes controlling each of the plurality of heaters based on the determined maximum optical modulation amplitude, which has been modified according to a scaling value of the optical modulator device corresponding to the heater.

[0075] In one or more embodiments, the scaling value for the optical modulator device is one of a plurality of scaling values ​​associated with a plurality of optical modulator devices. In other embodiments, the scaling value for the optical modulator device is the same scaling value for all optical modulator devices among the plurality of optical modulator devices.

[0076] 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.

[0077] In one or more implementations, two or more operations in operation 505 or 510 are performed substantially simultaneously (synchronously).

[0078] Figure 6 This is a flowchart of a method 600 for operating an optoelectronic device according to some examples. In one or more embodiments, the optoelectronic device is an example of at least a portion of an optical modulator block 130 and a control circuit 190 in a set of optical modulator blocks 131.

[0079] At 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 ​​exceeding a threshold. In one or more embodiments, the method includes identifying a first heater control value exceeding a threshold associated with a first photodiode current value within a range of heater control values; and then adjusting the range to determine a plurality of heater control values ​​based at least in part on a range of heater control values ​​exceeding the threshold.

[0080] At operation 610, the method includes transmitting a data pattern to an optical modulator device of an optoelectronic device.

[0081] At operation 615, the method includes each of a plurality of heater control values ​​for a heater thermally coupled to the optical modulator device, wherein the optical modulation amplitude corresponding to the heater control value is identified at least in part based on the corresponding photodiode current value identified during the data transmission mode.

[0082] At operation 620, the method includes determining the maximum optical modulation amplitude of the optical modulator device based on an identifier that is at least partially based on a plurality of optical modulation amplitudes corresponding to a plurality of heater control values.

[0083] At operation 625, the method includes controlling the heater at least in part based on a determined maximum optical modulation amplitude that has been modified according to the scaling value.

[0084] In one or more embodiments, two or more operations of 610 or 615 are performed substantially simultaneously (synchronously). In one or more embodiments, operation 605 is performed after or substantially simultaneously (synchronously) one or more of operations of 610, 615, 620 or 625.

[0085] In one or more embodiments, one or more operations of method 500 may be combined with one or more operations of method 600.

[0086] The above technology may be described in one or more of the following non-limiting embodiments.

[0087] Example 1: A method of operating an optoelectronic device, the method comprising: transmitting a data pattern to an optical modulator device of the optoelectronic device; identifying, at least in part, an optical modulation amplitude corresponding to each of a plurality of heater control values ​​of a heater thermally coupled to the optical modulator device based on a corresponding photodiode current value identified during the transmission of the data pattern; determining, based at least in part, a maximum optical modulation amplitude of the optical modulator device based on the identification and at least in part on the plurality of optical modulation amplitudes corresponding to the plurality of heater control values; and controlling the heater at least in part based on the determined maximum optical modulation amplitude, which has been modified according to a scaling value.

[0088] Example 2: According to the method described in Example 1, the data pattern includes a series of alternating "0" bits and "1" bits.

[0089] Example 3: According to the method of Example 1, the method further includes: identifying a first heater control value associated with a first photodiode current value within a range of heater control values ​​exceeding a threshold; and adjusting the range at least in part based on the range of the heater control values ​​exceeding the threshold to determine the plurality of heater control values.

[0090] Example 4: According to the method of Example 1, the method further includes: determining a maximum optical modulation amplitude for each of a plurality of optical modulator devices, each of the plurality of optical modulator devices being associated with a corresponding heater among a plurality of heaters; and controlling each of the plurality of heaters according to the determined maximum optical modulation amplitude, the maximum optical modulation amplitude having been modified according to a scaling value of the optical modulator device corresponding to the heater.

[0091] Example 5: According to the method of Example 4, the scaling value for the optical modulator device is one of a plurality of scaling values ​​associated with the plurality of optical modulator devices.

[0092] Example 6: According to the method of Example 4, the scaling value for the optical modulator device is the same scaling value for all optical modulator devices among the plurality of optical modulator devices.

[0093] Example 7: The optical modulator device according to the method of Example 1 includes a silicon microring modulator.

[0094] Example 8: The method according to Example 1, wherein the heater is controlled by a digital signal processor.

[0095] 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, the control circuit being configured to: transmit a data mode to the optical modulator device; for each of a plurality of heater control values ​​of the heater, identify an optical modulation amplitude corresponding to the heater control value based at least in part on a corresponding photodiode current value identified during the transmission of the data mode; determine a maximum optical modulation amplitude of the optical modulator device based at least in part on a plurality of optical modulation amplitudes corresponding to the plurality of heater control values; and control the heater based at least in part on the determined maximum optical modulation amplitude, which has been modified according to a scaling value.

[0096] Example 10: The optoelectronic device according to Example 9, wherein the data mode includes a series of alternating "0" bits and "1" bits.

[0097] Example 11: According to the optoelectronic device of Example 9, wherein the control circuit is further configured to: identify a first heater control value associated with a first photodiode current value within a range of heater control values ​​exceeding a threshold; and adjust the range at least in part based on the range of heater control values ​​exceeding the threshold to determine the plurality of heater control values.

[0098] Example 12: According to the optoelectronic device of Example 9, the optoelectronic device further includes: a plurality of optical modulator devices coupled to the control circuit; and a plurality of heaters, each of the plurality of optical modulator devices being associated with a corresponding heater among the plurality of heaters, wherein the control circuit is further configured to: determine a maximum optical modulation amplitude for each of the plurality of optical modulator devices; and control each of the plurality of heaters according to the determined maximum optical modulation amplitude, the maximum optical modulation amplitude having been modified according to a scaling value of the optical modulator device corresponding to the heater.

[0099] Example 13: The optoelectronic device according to Example 12, wherein the scaling value for the optical modulator device is one of a plurality of scaling values ​​associated with the plurality of optical modulator devices.

[0100] Example 14: The optoelectronic device according to Example 12, wherein the scaling value for the optical modulator device is the same scaling value for all optical modulator devices among the plurality of optical modulator devices.

[0101] Example 15: An integrated circuit device comprising: a communication interface for coupling the integrated circuit device to an optical modulator device, a heater, and a photodiode; and a control circuit coupled to the communication interface for: transmitting a data pattern to the optical modulator device via the communication interface; identifying an optical modulation amplitude corresponding to each of a plurality of heater control values ​​for the heater, at least in part based on a corresponding photodiode current value identified during the transmission of the data pattern; determining 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 controlling the heater via the communication interface, at least in part based on the determined maximum optical modulation amplitude, which has been modified according to a scaling value.

[0102] Example 16: The integrated circuit device according to Example 15, wherein the data pattern includes a series of alternating "0" bits and "1" bits.

[0103] Example 17: The integrated circuit device according to Example 15, wherein the control circuit is further configured to: identify a first heater control value associated with a first photodiode current value within a range of heater control values ​​exceeding a threshold; and adjust the range at least in part based on the range of heater control values ​​exceeding the threshold to determine the plurality of heater control values.

[0104] Example 18: According to the integrated circuit device of Example 15, the optoelectronic device further includes: a plurality of optical modulator devices coupled to the control circuit; and a plurality of heaters, each of the plurality of optical modulator devices being associated with a corresponding heater among the plurality of heaters, wherein the control circuit is further configured to: determine a maximum optical modulation amplitude for each of the plurality of optical modulator devices; and control via the communication interface. Each of the plurality of heaters is modified according to the determined maximum optical modulation amplitude, which has been modified according to a scaling value of the optical modulator device corresponding to the heater.

[0105] Example 19: The integrated circuit device according to Example 18, wherein the scaling value for the optical modulator device is one of a plurality of scaling values ​​associated with the plurality of optical modulator devices.

[0106] Example 20: The integrated circuit device according to Example 18, wherein the scaling value for the optical modulator device is the same scaling value for all optical modulator devices in the plurality of optical modulator devices.

[0107] While the foregoing describes specific embodiments, other and additional examples may be devised without departing from the basic scope of the invention, the scope of which is defined by the appended claims.

Claims

1. A method of operating an optoelectronic device, the method comprising: transmitting a data pattern to an optical modulator device of the optoelectronic device; for each of a plurality of heater control values of a heater thermally coupled to the optical modulator device, identifying an optical modulation amplitude value corresponding to the heater control value based at least in part on a corresponding photodiode current value identified at a time of transmitting the data pattern; determining, from the identifying, a maximum optical modulation amplitude value of the optical modulator device based at least in part on a plurality of optical modulation amplitude values corresponding to the plurality of heater control values; and controlling the heater based at least in part on the determined maximum optical modulation amplitude value that has been modified according to a scaling value.

2. The method of claim 1, the method further comprising: identifying that a first heater control value within a range of heater control values associated with a first photodiode current value exceeds a threshold value; and adjusting the range to determine the plurality of heater control values based at least in part on the range of heater control values exceeding the threshold value.

3. The method of claim 1, the method further comprising: for each of a plurality of optical modulator devices, determining a maximum optical modulation amplitude value of the optical modulator device, each of the plurality of optical modulator devices being associated with a corresponding heater of a plurality of heaters; and controlling each of the plurality of heaters from the determined maximum optical modulation amplitude values that have been modified according to a scaling value of the optical modulator device corresponding to the heater.

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

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

6. The method of claim 1, wherein the optical modulator device comprises a silicon microring modulator.

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

8. An optoelectronic device, the 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 control circuitry coupled to the heater and the photodiode, the control circuitry to: transmit a data pattern to the optical modulator device; for each of a plurality of heater control values of the heater, identify an optical modulation amplitude value corresponding to the heater control value based at least in part on a corresponding photodiode current value identified at a time of transmitting the data pattern; determine a maximum optical modulation amplitude value of the optical modulator device based at least in part on a plurality of optical modulation amplitude values corresponding to the plurality of heater control values; and control the heater based at least in part on the determined maximum optical modulation amplitude value that has been modified according to a scaling value. ​ controlling the heater based at least in part on the determined maximum optical modulation amplitude that has been modified according to a scaling value.

9. The optoelectronic device of claim 8, further comprising: a plurality of optical modulator devices coupled with the control circuit; and a plurality of heaters, each optical modulator device of the plurality of optical modulator devices being associated with a corresponding heater of the plurality of heaters, wherein the control circuit is further to: determine, for each optical modulator device of the plurality of optical modulator devices, a maximum optical modulation amplitude of the optical modulator device; and control each heater of the plurality of heaters according to the determined maximum optical modulation amplitude that has been modified according to a scaling value of the optical modulator device corresponding to the heater.

10. An integrated circuit device, comprising: a communication interface to couple the integrated circuit device with an optical modulator device, a heater, and a photodiode; and a control circuit coupled with the communication interface to: transmit, via the communication interface, a data pattern to the optical modulator device; identify, for each heater control value of a plurality of heater control values for the heater, an optical modulation amplitude value corresponding to the heater control value based at least in part on a corresponding photodiode current value identified while transmitting the data pattern; determine, based at least in part on a plurality of optical modulation amplitude values corresponding to the plurality of heater control values, a maximum optical modulation amplitude of the optical modulator device; and control, via the communication interface, the heater based at least in part on the determined maximum optical modulation amplitude that has been modified according to a scaling value.

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

12. The optoelectronic device of claim 8 or the integrated circuit device of claim 10, wherein the control circuit is further to: identify that a first heater control value within a range of heater control values associated with a first photodiode current value exceeds a threshold value; and adjust the range to determine the plurality of heater control values based at least in part on the range of heater control values exceeding the threshold value.

13. The integrated circuit device of claim 10, further comprising: a plurality of optical modulator devices coupled with the control circuit; and a plurality of heaters, each optical modulator device of the plurality of optical modulator devices being associated with a corresponding heater of the plurality of heaters, wherein the control circuit is further to: determine, for each optical modulator device of the plurality of optical modulator devices, a maximum optical modulation amplitude of the optical modulator device; and control each heater of the plurality of heaters according to the determined maximum optical modulation amplitude that has been modified according to a scaling value of the optical modulator device corresponding to the heater. According to the determined maximum optical modulation amplitude, which has been modified according to a scaling value for the optical modulator device corresponding to the heater, each of the plurality of heaters is controlled via the communication interface.

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

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

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