KR20210104197A - Wavelength Division Multiplexing Optical Transceiver based on Monolithically Integrated Micro Ring Integrated Circuits - Google Patents

Abstract

A wavelength division multiplexing optical transmitter based on a micro-ring optical integrated circuit with a single substrate structure of the present invention includes: a transmitting optical device unit which includes an optical coupler that receives an optical signal including a plurality of wavelengths from a laser source and transmits the received optical signal through an optical waveguide, and a micro-ring resonator based optical modulator that is formed to be separated from the optical waveguide by a predetermined distance and resonates at a specific wavelength among the plurality of wavelengths; and a transmitting electronic device unit which controls the optical modulator to convert the optical signal to generate a wavelength division multiplexing (WDM) signal composed of a plurality of wavelengths.

Description

Wavelength Division Multiplexing Optical Transceiver based on Monolithically Integrated Micro Ring Integrated Circuits

The present invention relates to a wavelength division multiplexing optical transceiving device, and more particularly, to a wavelength division multiplexing optical transceiving device based on a micro-ring optical integrated circuit having a single substrate structure.

Conventionally, since the optical device and the electronic device were implemented as a heterogeneous substrate and integrated at the packaging level, the temperature compensation of the micro-ring resonator was not accurately performed, so it was not widely used.

Korean Patent Laid-Open Publication No. 2003-0006439 published on January 23, 2003 (Title: Optical Transmitting Device and Optical Communication Method)

It is an object of the present invention to provide a wavelength division multiplexing optical transceiver based on a micro-ring optical integrated circuit having a single substrate structure.

A wavelength division multiplexing optical transmitter based on a micro-ring optical integrated circuit having a single substrate structure according to a preferred embodiment of the present invention for achieving the above object receives an optical signal including a plurality of wavelengths from a laser source and input A transmitting optical element unit including an optical coupler for transmitting the optical signal through an optical waveguide, a micro-ring resonator-based optical modulator formed to be spaced apart from the optical waveguide by a predetermined distance and resonating at a specific wavelength among the plurality of wavelengths; It is formed on the same substrate as the transmit electronic device and includes a transmit electronic device for controlling the optical modulator to convert the optical signal to generate a wavelength division multiplexing (WDM) signal composed of a plurality of wavelengths.

The transmission electronic device unit includes a transmission signal processing module for outputting an electrical signal, a transmission input/output module for matching the signal level of the electrical signal, a serializer for converting the electrical signal into a plurality of electrical signals, and the optical modulator including the plurality of electrical signals. and a driver for driving the optical modulator by inputting the plurality of electrical signals to the optical modulator to convert the optical signal according to the electrical signal to generate a wavelength division multiplexed signal having a plurality of wavelengths.

The transmission electronic device unit detects a change in characteristics according to the temperature of the micro-ring resonator and adjusts the temperature of the micro-ring resonator in a manner to control the voltage of a heater built into the micro-ring resonator, thereby resonating the micro-ring resonator. It further includes a transmission wavelength controller for controlling the wavelength.

The wavelength of the micro-ring resonator is characterized in that it is determined by the size of the micro-ring of the micro-ring resonator and the distance between the micro-ring and the optical waveguide.

A wavelength division multiplexing optical receiver based on a micro-ring optical integrated circuit of a single substrate structure according to a preferred embodiment of the present invention for achieving the above object is a wavelength division multiplexing (WDM) including a plurality of wavelengths (WDM: Wavelength Division Multiplexing) A receiving optical element unit for extracting a plurality of electrical signals corresponding to a plurality of wavelengths from the signal, and the receiving optical element unit formed on the same substrate as the receiving optical element unit, and controlling the receiving optical element unit to extract a plurality of electrical signals from the wavelength division multiplexing signal, , and a receiving electronic device for amplifying the plurality of electrical signals and converting them into digital signals.

The optical receiver unit includes an optical coupler receiving the wavelength division multiplexing signal, an optical waveguide transmitting the wavelength division multiplexing signal, and an optical signal corresponding to a plurality of wavelengths of the wavelength division multiplexing signal transmitted through the optical waveguide It includes a micro-ring-based wavelength filter that receives the light, and a photodiode that converts an optical signal output from the wavelength filter into an electrical signal.

The receiving electronic device unit converts and amplifies the electrical signal of the current output from the photodiode into a voltage and amplifies a transimpedance amplifier for outputting an electrical signal having the amplified voltage and a limiter for converting the output electrical signal into a high-speed electrical signal. A receiver comprising: a parallelizer for slowing down and parallelizing and outputting a high-speed electrical signal output from the receiver; a reception input/output module for inputting the electrical signal output from the parallelizer to a reception signal processing module; and the received signal processing module for providing a signal to the application layer.

The reception electronic device unit includes a reception wavelength controller for controlling the resonance wavelength of the micro-ring resonator by adjusting the voltage of the heater built in the micro-ring resonator of the micro-ring resonator-based wavelength filter.

According to the present invention, by configuring a micro-ring-based optical integrated circuit with a CMOS SOI (Silicon on Insulator) single substrate structure, its temperature sensitivity can be corrected in real time.

1 is a diagram for explaining the configuration of a wavelength division multiplexing optical transceiver based on a micro-ring optical integrated circuit having a single substrate structure according to an embodiment of the present invention.
2 is a view for explaining the resonance wavelength of the micro ring resonator according to an embodiment of the present invention.
3 is a view for explaining a configuration for controlling a wavelength change according to the temperature of the micro-ring resonator of the optical transmission device according to an embodiment of the present invention.
4 is a diagram for explaining a configuration for processing a received signal of an optical receiving apparatus according to an embodiment of the present invention.

Prior to the detailed description of the present invention, the terms or words used in the present specification and claims described below should not be construed as being limited to their ordinary or dictionary meanings, and the inventors should develop their own inventions in the best way. For explanation, it should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be appropriately defined as a concept of a term. Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention, and do not represent all of the technical spirit of the present invention, so various equivalents that can be substituted for them at the time of the present application It should be understood that there may be water and variations.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this case, it should be noted that the same components in the accompanying drawings are denoted by the same reference numerals as much as possible. In addition, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some components are exaggerated, omitted, or schematically illustrated in the accompanying drawings, and the size of each component does not fully reflect the actual size.

First, a configuration of a wavelength division multiplexing optical transceiver based on a micro-ring optical integrated circuit having a single substrate structure according to an embodiment of the present invention will be described. 1 is a diagram for explaining the configuration of a wavelength division multiplexing optical transceiver based on a micro-ring optical integrated circuit having a single substrate structure according to an embodiment of the present invention. 2 is a view for explaining the resonance wavelength of the micro ring resonator according to an embodiment of the present invention.

Referring to FIG. 1 , a wavelength division multiplexing optical transceiving device according to an embodiment of the present invention includes an optical transmitting device 10 and an optical receiving device 20 , and the optical transmitting device 10 includes a transmitting optical device unit 100 . and a transmitting electronic device unit 200 , and the light receiving device 20 includes a receiving optical device unit 300 and a receiving electronic device unit 400 .

The optical transmission device 10 including the above-described transmission optical device unit 100 and the transmission electronic device unit 200 is formed on one substrate. That is, the transmitting optical device unit 100 and the transmitting electronic device unit 200 are formed on one substrate. In addition, the light receiving device 20 including the receiving optical device unit 300 and the receiving electronic device unit 400 is formed on one substrate. The receiving optical device unit 300 and the receiving electronic device unit 400 are formed on one substrate. In addition, the light transmitting device 10 and the light receiving device 20 may be selectively formed on one substrate.

Then, each of the transmitting optical device unit 100 , the transmitting electronic device unit 200 , the receiving optical device unit 300 , and the receiving electronic device unit 400 will be described.

First, the transmission optical device unit 100 will be described. The transmission optical device unit 100 includes a grating type optical coupler 110 (Grating Coupler), an optical waveguide 120, and N micro-ring resonator-based optical modulators 130 (MR modulator).

The grating type optocoupler 110 serves as an input/output port of an optical signal. When N is a natural number of 2 or more, that is, plural, the optical coupler 110 receives N wavelength signals from the laser source 30 (CW Laser: Continuous-Wave Laser) and transmits the N wavelength signals to the optical waveguide 120 . transmitted through When the laser source 30 is a multi-wavelength laser, one optical coupler 110 receives N wavelengths, and when the N laser sources 30 output different wavelengths, a multimode interferometer (MMI) (not shown) must be additionally configured between the laser source 30 and the optocoupler 110 .

The micro-ring resonator (MR)-based optical modulator 130 is designed to resonate at a specific wavelength among N wavelengths. The wavelength of each micro-ring resonator is determined by the size 131 of the micro-ring resonator (MR) and the gap (132, Gap) between the micro-ring resonator (MR) and the optical waveguide 120, as shown in FIG. And through proper design, it is possible to create a desired resonant wavelength in wavelength division multiplexing. In particular, the optical modulator 130 generates a wavelength division multiplexing (WDM) signal composed of N wavelengths by converting the N wavelength signals transmitted to the optical waveguide 120 through resonance. Accordingly, a wavelength division multiplexing (WDM) signal is transmitted through the optical waveguide 120 .

Next, the transmission electronic device unit 200 will be described. The transmission electronic device unit 200 largely performs two roles. First, the transmission electronic device unit 200 drives the micro-ring resonator-based optical modulator 130 at high speed. Second, the transmission electronic device unit 200 serves to control the wavelength change of the optical modulator 130 according to the temperature of the micro ring.

Transmission electronic device unit 200 includes a transmission signal processing module (210: MCU & Digital Logic Blocks), a transmission input/output module (220: Transmitter I/O Parts), a serializer (230: Serializer), and a driver (240: Modulator Driver) and a transmission wavelength controller 250 (MR Control).

The transmission signal processing module 210 generates an electrical signal according to an input from an upper layer (eg, an application layer) and outputs the electrical signal, and the transmission input/output module 220 adjusts the signal level of the electrical signal, and a serializer 230 converts the electrical signal into high-speed N electrical signals. Accordingly, the driver 240 drives the optical modulator 130 at high speed through N high-speed electrical signals. That is, the optical modulator 130 inputs N electrical signals to the optical modulator 130, and the optical modulator 130 converts N wavelength signals transmitted to the optical waveguide 120 according to the N electrical signals input. A wavelength division multiplexing (WDM) signal composed of N wavelengths is generated.

The serializer 230 may be configured in various ways, such as 8:1, 16:1, 10:4, etc. depending on the system. The serializer 230 includes a clock generator (PLL) for serialization and may further include a clock and data recovery (CDR) function serving as a retimer if necessary.

The transmission wavelength controller 250 (MR Control) controls the resonance wavelength of the micro-ring resonator by sensing a characteristic change according to the temperature of the micro-ring resonator and controlling a heater voltage built into the micro-ring resonator. To this end, the transmission wavelength controller 250 includes a function of monitoring at least one of the temperature and the resonance wavelength of the micro ring resonator in real time.

As described above, the light receiving device 20 includes the receiving optical device unit 300 and the receiving electronic device unit 400 .

First, the receiving optical device unit 300 performs the opposite role of the transmitting optical device unit 100 . That is, when N is a natural number greater than or equal to 2, that is, plural, the receiving optical device unit 300 receives N from a Wavelength Division Multiplexing (WDM) signal including N wavelengths transmitted from the optical transmitter 10 . N electrical signals are extracted for each wavelength. The optical optical device unit 300 includes an optical coupler 310 , an optical waveguide 320 , a micro-ring resonator-based wavelength filter 330 , and a photodiode (PD) 340 .

The optical coupler 310 receives a Wavelength Division Multiplexing (WDM) signal including N wavelengths transmitted from the optical transmitter 10 and transmits it to the optical waveguide 320 .

The optical waveguide 320 transmits a wavelength division multiplexing (WDM) signal.

The N micro-ring-based wavelength filters 330 receive an optical signal corresponding to each resonant wavelength from a wavelength division multiplexing (WDM) signal transmitted through the optical waveguide 320 .

The photodiode 340 is connected to each of the N micro-ring-based wavelength filters 330 , and each photodiode 340 converts an optical signal output from the corresponding micro-ring-based wavelength filter 330 into an electrical signal. .

Next, the receiving electronic device unit 400 amplifies the electrical signal output from the photodiode 340 of the receiving optical device unit 300 and converts it into a signal capable of digital signal processing. The reception electronic device unit 400 includes a reception signal processing module (MCU & Digital Logic Blocks, 410), a reception input/output module (Receiver I/O Parts, 420), a parallelizer (Deserializer, 430), and a receiver (Receiver, 440). and a reception wavelength controller (MR Control, 450).

The reception wavelength controller 450 detects a characteristic change according to the temperature of the micro-ring resonator of the micro-ring resonator-based wavelength filter 330 to control the voltage of a heater built into the micro-ring resonator. control the wavelength.

The receiver 440 receives and amplifies the electrical signal output from the photodiode, and then outputs a high-speed electrical signal.

The deserializer 430 parallelizes the high-speed electrical signal output from the receiver 440, lowers the speed, and converts the signal to facilitate signal processing.

The reception input/output module 420 inputs the electrical signal output from the parallelizer 430 to the reception signal processing module 410 . Accordingly, the reception signal processing module 410 may receive the electrical signal and provide it to the application layer.

Next, a configuration for controlling the wavelength change according to the temperature of the micro ring resonator of the optical transmitter 10 according to an embodiment of the present invention will be described. 3 is a view for explaining a configuration for controlling a wavelength change according to the temperature of the micro-ring resonator of the optical transmission device according to an embodiment of the present invention.

3, the optical waveguide 120 and the micro-ring resonator (MR)-based optical modulator 130 of the transmitting optical device unit 100 are shown, and the serializer 230 and the driver 240 of the transmitting electronic device 200 are shown. and a transmission wavelength controller 250 are shown. The optical transmitter 10 may further include a 64-bit pattern generator 260 and a PRBS-31 signal generator 270 as in the embodiment shown in FIG. 3 for self-bit error rate testing. In the embodiment of FIG. 3, the 8:1 serializer 230 is shown as an example, and the PLL for generating the clock CK is omitted.

Referring to FIG. 3, the transmission wavelength controller 250 includes a diode 251, a front end 252 including one or more amplifiers 252a and a comparator 252b, and a successive comparison register (SAR: Successive Approximation Register, 253). , counter, tracker, a plurality of digital logic circuits such as cancellation logic (Cancellation) (254a, 254b, 254c, 254d), a finite state machine (FSM: Finite State Machine, 255), analog converter (DAC) : Digital to Analog Converter, 256) and a heater driver 257.

A photodiode 251 capable of monitoring an optical signal in real time is individually configured in each micro ring resonator (MR). The optical signal detected by the photodiode 251 in the front end 252 is separated from the DC value and the AC value of the electrical signal through the comparator 252a and the sequential comparison register (SAR, 253), and converted into a digital signal. do. Then, a finite state machine (FSM) 255 generates an optimal code from the previously converted digital signal through the digital logic circuits 254a, 254b, 254c, and 254d. The digital signal thus generated is input to the heater driver 257 through a Digital to Analog Converter (DAC) 256, and the heater driver 257 controls the heater built into the micro ring resonator MR.

Next, a configuration for processing a received signal of the optical receiving device 20 according to an embodiment of the present invention will be described. 4 is a diagram for explaining a configuration for processing a received signal of an optical receiving apparatus according to an embodiment of the present invention.

In FIG. 4 , a photodiode 340 of the receiving optical device unit 300 is shown, and a receiver 440 and a parallelizer 430 of the receiving electronic device unit 400 are shown.

The receiver 440 receives and amplifies the electrical signal output from the photodiode 340 and outputs a high-speed electrical signal. For this, the receiver 440 includes a Transimpedance Amplifier (TIA) 441 and a Limiter 442 . In addition, the receiver 440 further includes a retimer 443 .

The transimpedance amplifier (TIA, 441) has a resistance (R) feedback, and converts the microcurrent signal input from the photodiode 340 into a voltage signal and amplifies it at the same time. The limiter 442 is composed of a high-speed comparator circuit including a limiting amplifier (Limiting Amplifier, 442a). The high-speed electrical signal passing through the limiter 442 is input to the parallelizer 430 through a retiming process in the retarder 443 . The parallelizer 430 includes a plurality of latches (L, Latch) and a plurality of flip-flops (FF, Flip-Flop), and slows down a high-speed electrical signal.

On the other hand, the conventional optical integrated circuit is a method of hybrid integration based on a high-level packaging technology by composing an optical device and an electronic device on a heterogeneous substrate. There were limits. Therefore, since this temperature compensation is performed separately through an external device on the module, high power consumption and the accuracy of temperature compensation are deteriorated. However, the present invention provides an optical device including a micro-ring resonator on a single substrate (110, 120, 130, 310, 320, 330, 340) and a high-speed electronic circuit (210 to 250, 410 to 450) capable of controlling and driving the same. By implementing this, it is possible to check the temperature in real time and compensate to maintain the best transmission performance. Furthermore, in the present invention, analog circuits and digital logic required for optical transmission and reception, active/passive optical devices, and compensation circuits capable of controlling them are configured on a single substrate 10/20. In the conventional optical integrated circuit, the optical device is a group III-V compound semiconductor, and the electronic device is implemented as a silicon-based CMOS semiconductor and hybridized through wafer level package (WLP) and precision optical alignment technology. This has a limitation in terms of bandwidth and increases packaging cost, which is a factor that lowers price competitiveness. On the other hand, in the present invention, the optical devices 110, 120, 130, 310, 320, 330, 340 and the electronic devices 210 to 250, 410 to 450 are integrated on a single substrate 10/20 through a silicon-based process. can do. Accordingly, it is possible to implement an optical transmission/reception chipset using a micro-ring resonator capable of maximizing the price competitiveness of the chipset. In particular, the micro ring resonator simultaneously functions as an optical modulator and a wavelength division multiplexer in the optical transmission device 10, and serves as a wavelength division demultiplexer in the optical reception device 20, thereby greatly reducing the size of the transceiver chipset. . However, the micro ring resonator has a disadvantage in that it is vulnerable to process, voltage, and temperature variations (PVT variations). In order to compensate for this disadvantage, in the present invention, an optical integrated circuit is configured much more efficiently than the conventional hybrid type by implementing analog and digital electronic circuits 250 and 450 that can monitor and compensate in real time on a single substrate. can do. That is, in the present invention, a micro-ring-based optical integrated circuit can be configured with a CMOS SOI (Silicon on Insulator) single substrate structure and its temperature sensitivity can be corrected in real time.

In summary, the optical device of the conventional optical integrated circuit is a III-V compound semiconductor, and the electronic device is implemented as a silicon-based CMOS semiconductor, which is a hybrid through wafer level package (WLP, Wafer Level Package) and precision optical alignment technology. Although it was integrated, it has limitations in terms of bandwidth and increased packaging cost, which lowered price competitiveness. In the present invention, an optical transmission/reception chipset using a micro-ring resonator capable of integrating an optical device and an electronic device on a single substrate through a silicon-based process and maximizing the price competitiveness of the chipset is implemented. The micro ring resonator simultaneously functions as an optical modulator and a wavelength division multiplexer in the optical transmission device 10 , and serves as a wavelength division demultiplexer in the optical reception device 20 , thereby greatly reducing the size of the transceiver chipset. However, the micro ring resonator has a disadvantage in that it is vulnerable to process, voltage, and temperature variations (PVT variations). In the present invention, by implementing analog and digital electronic circuits 250 and 450 capable of monitoring and compensating in real time on a single substrate, an optoelectronic integrated optical transceiver circuit can be configured much more efficiently than the conventional hybrid type. The micro ring resonator used in the optical integrated circuit consumes a very small chip area of about 8 μm to 20 μm depending on the center wavelength, and has a size of about 1/30 compared to the Mach-Zehnder modulator used as an existing optical modulator, and is a conventional wavelength filter. Compared to the used AWG (Arrayed Waveguide Grating) device, it is about 1/100th the size of the chip, and the price of the chip can be greatly reduced. In addition, by implementing the optical devices 110, 120, 130, 310, 320, 330, 340 and the electronic devices 210 to 250, 410 to 450 together on a single substrate 10/20, the optical devices 110, 120, 130, 310, 320, 330, 340) has an advantage in monitoring and compensating for characteristics according to changes in the surrounding environment, such as temperature. In addition, in the existing optical transceiver, the modulator and the wavelength division multiplexer were used as separate optical elements, but the micro-ring resonator simultaneously plays this role in both transmission and reception, greatly improving the bandwidth.

Although the present invention has been described above using several preferred embodiments, these examples are illustrative and not restrictive. As such, those of ordinary skill in the art to which the present invention pertains will understand that various changes and modifications can be made in accordance with the doctrine of equivalents without departing from the spirit of the present invention and the scope of rights set forth in the appended claims.

10: optical transmitter
20: optical receiver
100: transmit optical element unit
110: optocoupler
120: optical waveguide
130: optical modulator
200: transmit electronic device unit
210: transmission signal processing module
220: transmission input/output module
230: serializer
240: actuator
250: transmission wavelength controller
300: receiving light element unit
310: optocoupler
320: optical waveguide
330: wavelength filter
400: receiving electronic device unit
410: reception signal processing module
420: receive input output module
430: parallelizer
440: receiver
450: receive wavelength controller

Claims (8)

In a wavelength division multiplexing optical transmission device based on a micro-ring optical integrated circuit having a single substrate structure,
An optical coupler that receives an optical signal including a plurality of wavelengths from a laser source and transmits the input optical signal through an optical waveguide;
A micro-ring resonator-based optical modulator that is formed to be spaced apart from the optical waveguide by a predetermined distance and resonates at a specific wavelength among the plurality of wavelengths.
Transmitting optical element unit comprising a; and
a transmitting electronic device unit formed on the same substrate as the transmitting electronic device unit and controlling the optical modulator to convert the optical signal to generate a wavelength division multiplexing (WDM) signal composed of a plurality of wavelengths;
characterized by comprising
optical transmitter. According to claim 1,
The transmitting electronic device unit
a transmission signal processing module for outputting an electrical signal;
a transmission input/output module for matching the signal level of the electrical signal;
a serializer for converting the electrical signal into a plurality of electrical signals; and
a driver for driving the optical modulator by inputting the plurality of electrical signals to the optical modulator so that the optical modulator converts the optical signal according to the plurality of electrical signals to generate a wavelength division multiplexed signal having a plurality of wavelengths; characterized by including
optical transmitter. According to claim 1,
The transmitting electronic device unit
Transmission for controlling the resonance wavelength of the micro-ring resonator by controlling the temperature of the micro-ring resonator in a manner that detects a characteristic change according to the temperature of the micro-ring resonator and controls a heater voltage built into the micro-ring resonator Wavelength controller; characterized in that it further comprises
optical transmitter. 4. The method of claim 3,
The wavelength of the micro ring resonator is
Characterized in that it is determined by the size of the micro ring of the micro ring resonator and the distance between the micro ring and the optical waveguide.
optical transmitter. In a wavelength division multiplexing optical receiving device based on a micro-ring optical integrated circuit having a single substrate structure,
a receiving optical element unit for extracting a plurality of electrical signals corresponding to a plurality of wavelengths from a wavelength division multiplexing (WDM) signal including a plurality of wavelengths; and
a receiving electronic device formed on the same substrate as the receiving optical device, controlling the receiving optical device to extract a plurality of electrical signals from the wavelength division multiplexing signal, and amplifying the plurality of electrical signals to convert them into digital signals;
characterized by comprising
optical receiver. 6. The method of claim 5,
The receiving light element unit
an optical coupler receiving the wavelength division multiplexing signal;
an optical waveguide for transmitting the wavelength division multiplexing signal;
a micro-ring-based wavelength filter for receiving optical signals corresponding to a plurality of wavelengths of the wavelength division multiplexing signal transmitted through the optical waveguide; and
a photodiode for converting an optical signal output from the wavelength filter into an electrical signal;
characterized by comprising
optical receiver. 7. The method of claim 6,
The receiving electronic device unit
a receiver including a transimpedance amplifier that converts and amplifies an electrical signal of the current output from the photodiode into a voltage and outputs an electrical signal having the amplified voltage and a limiter that converts the output electrical signal into a high-speed electrical signal;
a parallelizer for slowing down and parallelizing the high-speed electrical signal output from the receiver;
a reception input/output module for inputting the electrical signal output from the parallelizer to the reception signal processing module; and
the received signal processing module for providing the input electrical signal to an application layer;
characterized by comprising
optical receiver. 7. The method of claim 6,
The receiving electronic device unit
of the micro-ring resonator-based wavelength filter
By controlling the voltage of the heater built into the micro ring resonator,
to control the resonance wavelength of the micro-ring resonator
receiving wavelength controller;
characterized by comprising
optical receiver.

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