A wavelength demodulation system for wavelength division multiplexing based on microring resonator

Abstract

The invention discloses a wavelength demodulation system for wavelength division multiplexing based on a microring resonator, comprising a microring resonator chip, a modulation signal generating circuit, a photoelectric signal conversion circuit and a frequency mixing filter circuit; the modulation signal generating circuit generates a sinusoidal oscillation modulation signal with a DC bias, and transmits it to the microring resonator chip and the frequency mixing filter circuit; the microring resonator chip converts input optical signals of different wavelengths into optical signals related to the wavelength, and transmits them to the photoelectric signal conversion circuit; the photoelectric signal conversion circuit converts the optical signal output by the microring resonator chip into an electrical signal, and transmits it to the frequency mixing filter circuit after amplification, and the frequency mixing filter circuit realizes the mixing and filtering of the sinusoidal oscillation modulation signal transmitted by the modulation signal generating circuit and the converted electrical signal, and outputs the demodulated voltage signal. The demodulation system disclosed by the invention can demodulate the sensor reflection signal based on a wide-spectrum light source, has low cost and small size, and can realize large-scale multiplexing.

Description

Technical Field

[0001] The invention belongs to the field of optoelectronic technology, and in particular to a wavelength division multiplexing wavelength demodulation system based on a micro-ring resonator. Background Art

[0002] Sensors such as fiber Bragg grating sensors, microring sensors and Fabry-Perot sensors convert changes in physical quantities into changes in light wavelengths, and the changes in the sensed physical quantities can be obtained by demodulating the light wavelengths.

[0003] At present, most wavelength demodulators on the market are based on DFB lasers. By controlling the temperature, the laser gradually scans the wavelength of the sensor, and the light intensity of the return signal is used to identify the working wavelength of the sensor. Due to the high cost of lasers, demodulators are expensive and have poor reusability. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a wavelength division multiplexing wavelength demodulation system based on a microring resonator, so as to demodulate the sensor reflection signal based on a wide-spectrum light source and realize large-scale multiplexing.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A wavelength demodulation system for wavelength division multiplexing based on a microring resonator comprises a microring resonator chip, a modulation signal generating circuit, a photoelectric signal conversion circuit and a frequency mixing and filtering circuit; the modulation signal generating circuit generates a sinusoidal wave oscillation modulation signal with a DC bias, and transmits it to the microring resonator chip and the frequency mixing and filtering circuit; the microring resonator chip converts input optical signals of different wavelengths into optical signals related to the wavelength, and transmits them to the photoelectric signal conversion circuit; the photoelectric signal conversion circuit converts the optical signal output by the microring resonator chip into an electrical signal, and transmits it to the frequency mixing and filtering circuit after amplification; the frequency mixing and filtering circuit realizes mixing and filtering of the sinusoidal wave oscillation modulation signal transmitted by the modulation signal generating circuit and the converted electrical signal, and outputs a demodulated voltage signal.

[0007] In the above scheme, the microring resonator chip includes a silicon substrate and a silicon dioxide layer located on the silicon substrate, a waveguide layer is buried in the silicon dioxide layer, and the waveguide layer includes a grating coupler, an arrayed waveguide grating and a plurality of microring resonators. The optical signal in the optical fiber is coupled into the microring resonator chip by the grating coupler, and the optical signals of different wavelengths are branched to each microring resonator through the arrayed waveguide grating for demodulation respectively; a titanium nitride film is prepared in the silicon dioxide layer above the microring resonator, and the titanium nitride film is connected to an electrode, and the electrode is connected to a modulation signal generating circuit; a sinusoidal wave oscillation modulation signal is connected to the titanium nitride film through the electrode to modulate the optical signal entering the microring resonator; and the output end of the microring resonator chip is connected to a photoelectric signal conversion circuit.

[0008] In the above scheme, the photoelectric signal conversion circuit includes a photodiode, a transimpedance amplifier circuit and an operational amplifier circuit, which converts the optical signal output by the microring resonator chip into an electrical signal and amplifies it.

[0009] In the above scheme, the mixing and filtering circuit includes an analog multiplier circuit and a low-pass filtering circuit. The analog multiplier circuit realizes mixing of the sinusoidal oscillation modulation signal and the converted electrical signal, and the low-pass filtering circuit is used to filter out the high-frequency components after mixing.

[0010] In a further technical solution, the microring resonator is a racetrack type, the radius of the circular part is 25 μm, the length of the middle coupling part is 20 μm, and the coupling distance between the microring resonator and the transmission waveguides at the input end and the download end is 300 nm.

[0011] In a further technical solution, the titanium nitride film is located 1 μm above the microring resonator, and the impedance of the titanium nitride film is 760Ω.

[0012] Through the above technical solution, the wavelength division multiplexing wavelength demodulation system based on microring resonator provided by the present invention has the following beneficial effects:

[0013] The wavelength demodulation system of the present invention divides multiplexed optical signals by arrayed waveguide gratings, and each path is demodulated by a microring resonator. The demodulation of multiple signals can be completed on a single chip to achieve multiplexing.

[0014] The wavelength demodulation system of the present invention can demodulate a sensor using a low-cost broad-spectrum light source, and the demodulation optical path size is small and can be completed on a small chip, thereby realizing high-precision wavelength demodulation at low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0016] Figure 1 A schematic diagram of a wavelength division multiplexing wavelength demodulation system based on a microring resonator disclosed in an embodiment of the present invention;

[0017] Figure 2 is a cross-sectional view of a microring resonator chip;

[0018] Figure 3 is a planar layout diagram of a microring resonator chip;

[0019] Figure 4 for Figure 3 The enlarged schematic diagram of part A in the middle;

[0020] Figure 5 is the microring transfer function;

[0021] Figure 6 is the first-order derivative of the microring transfer function.

[0022] In the figure, 1, silicon substrate; 2, silicon dioxide layer; 3, grating coupler; 4, array waveguide grating; 5, microring resonator; 6, photodiode; 7, electrode; 8, titanium nitride film; 9, transmission waveguide. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0024] The present invention provides a wavelength division multiplexing wavelength demodulation system based on a microring resonator 5, such as Figure 1 As shown, it includes a microring resonator chip, a modulation signal generating circuit, an optoelectronic signal conversion circuit and a mixing filter circuit. The modulation signal generating circuit generates a sinusoidal oscillation modulation signal with a DC bias and transmits it to the microring resonator chip and the mixing filter circuit; the microring resonator chip converts the input optical signals of different wavelengths into optical signals related to the wavelength and transmits them to the optoelectronic signal conversion circuit; the optoelectronic signal conversion circuit converts the optical signal output by the microring resonator chip into an electrical signal, amplifies it and transmits it to the mixing filter circuit, the mixing filter circuit realizes the mixing and filtering of the sinusoidal oscillation modulation signal transmitted by the modulation signal generating circuit and the converted electrical signal, and outputs the demodulated voltage signal.

[0025] 1. Microring resonator chip

[0026] like Figure 2As shown, the microring resonator chip includes a silicon substrate 1 and a silicon dioxide layer 2 located on the silicon substrate 1, a waveguide layer is buried in the silicon dioxide layer 2, and the waveguide layer includes a grating coupler 3, an arrayed waveguide grating 4 and a plurality of microring resonators 5, and the grating coupler 3, the arrayed waveguide grating 4 and the plurality of microring resonators 5 are sequentially connected through a transmission waveguide 9. The optical signal in the optical fiber is coupled into the microring resonator chip by the grating coupler 3, and the optical signals of different wavelengths are branched to each microring resonator 5 through the arrayed waveguide grating 4 for demodulation respectively; a titanium nitride film 8 is prepared in the silicon dioxide layer 2 above the microring resonator 5, and the titanium nitride film 8 is connected to an electrode 7, and the electrode 7 is connected to a modulation signal generating circuit; the sinusoidal wave oscillation modulation signal is connected to the titanium nitride film 8 through the electrode 7 to modulate the optical signal entering the microring resonator 5; the output end of the microring resonator chip is connected to a photoelectric signal conversion circuit.

[0027] The microring resonator 5 is a racetrack type, the radius of the circular part is 25 μm, the length of the middle coupling part is 20 μm, and the coupling distance between the transmission waveguide 9 at the input end and the download end of the microring resonator 5 is 300 nm.

[0028] The titanium nitride film 8 is located 1 μm above the microring resonator 5 , and the impedance of the titanium nitride film 8 is 760Ω.

[0029] 2. Modulation signal generating circuit

[0030] The modulation signal generating circuit generates a sinusoidal oscillation modulation signal with a DC bias. The DC bias, the sinusoidal signal frequency, and the peak-to-peak value are adjustable.

[0031] 3. Photoelectric signal conversion circuit

[0032] The photoelectric signal conversion circuit includes a photodiode 6, a transimpedance amplifier circuit and an operational amplifier circuit. The photodiode 6 converts the optical signal into a current, the transimpedance amplifier circuit converts the current into a voltage, and the operational amplifier circuit amplifies the voltage. In the present invention, the photodiode 6 is integrated into the microring resonator chip to avoid the extra loss caused by connecting the optical fiber.

[0033] 4. Mixing filter circuit

[0034] The frequency mixing and filtering circuit comprises an analog multiplier circuit and a low-pass filtering circuit. The analog multiplier circuit realizes mixing of the sinusoidal oscillation modulation signal and the converted electrical signal, and the low-pass filtering circuit is used to filter out the high-frequency components after mixing.

[0035] The working principle of the demodulation system of the present invention is as follows:

[0036] The optical signal in the optical fiber is coupled into the microring resonator chip by the grating coupler 3, and the arrayed waveguide grating 4 branches the optical signals of different wavelengths to each microring resonator 5 for demodulation. The sinusoidal oscillation modulation signal is connected to the titanium nitride film 8 of the microring resonator chip through the electrode 7 to modulate the optical signal entering the microring resonator 5. The output end of the microring resonator chip is connected to the photoelectric conversion circuit through the photodiode 6. The photodiode 6 completes the photoelectric conversion of the signal and further amplifies it through the transimpedance amplifier circuit and the operational amplifier circuit. The mixing filter circuit realizes the extraction of the first harmonic component by spectrum shifting and low-pass filtering of the photoelectric conversion signal, and finally obtains a voltage signal related to the wavelength to complete the demodulation of the wavelength.

[0037] The modulation process of the optical signal by the microring resonator 5 is as follows:

[0038] like Figure 5 As shown, the micro-ring transfer function is:

[0039]

[0040] Among them, λ R is the microring resonance wavelength, and λ is the input optical signal wavelength.

[0041] Apply a sinusoidal oscillation modulation signal Acos(2πft) to the microring resonator 5, and the microring resonant wavelength is λ R =λ0+Δλcos(2πft).

[0042] The output optical power is:

[0043]

[0044] The photodiode 6 performs photoelectric conversion on the optical signal output by the microring resonator 5, and further amplifies it through the transimpedance amplifier circuit and the operational amplifier circuit. The output voltage signal is: V out =P out ×M, M is the total magnification.

[0045] The frequency mixing filter circuit extracts the first harmonic component by shifting the spectrum of the photoelectric conversion signal and performing low-pass filtering. The voltage signal obtained is proportional to the first-order derivative function of the transmission function of the microring resonator 5 .

[0046] The first-order derivative of the microring transfer function is Figure 6 As shown in the figure, the central symmetric point of the first-order derivative of the micro-ring transfer function corresponds to the DC voltage component of the modulation signal. The wide range of wavelength tracking can be achieved by scanning the DC component. When the DC component is determined, the wavelength change in a small range can be accurately tracked according to the fluctuation of the output signal.

[0047] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A wavelength division multiplexing wavelength demodulation system based on a microring resonator, characterized in that: It includes a microring resonator chip, a modulation signal generating circuit, a photoelectric signal conversion circuit and a mixing filter circuit; the modulation signal generating circuit generates a sinusoidal oscillation modulation signal with a DC bias and transmits it to the microring resonator chip and the mixing filter circuit; The microring resonator chip converts input optical signals of different wavelengths into optical signals related to the wavelengths, and transmits them to the photoelectric signal conversion circuit; the photoelectric signal conversion circuit converts the optical signal output by the microring resonator chip into an electrical signal, and transmits it to the mixing and filtering circuit after amplification, the mixing and filtering circuit realizes the mixing and filtering of the sinusoidal oscillation modulation signal transmitted by the modulation signal generating circuit and the converted electrical signal, and outputs the demodulated voltage signal; the microring resonator chip includes a silicon substrate and a silicon dioxide layer located on the silicon substrate, a waveguide layer is buried in the silicon dioxide layer, the waveguide layer includes a grating coupler, an arrayed waveguide grating and a plurality of microring resonators, the optical signal in the optical fiber is coupled into the microring resonator chip by the grating coupler, and the optical signals of different wavelengths are branched to each microring resonator through the arrayed waveguide grating for demodulation respectively; a titanium nitride film is prepared in the silicon dioxide layer above the microring resonator, the titanium nitride film is connected to an electrode, and the electrode is connected to the modulation signal generating circuit; The sinusoidal wave oscillation modulation signal is connected to the titanium nitride film through the electrode to modulate the optical signal entering the microring resonator; the output end of the microring resonator chip is connected to the photoelectric signal conversion circuit.

2. The wavelength division multiplexing wavelength demodulation system based on microring resonator according to claim 1, characterized in that: The photoelectric signal conversion circuit includes a photodiode, a transimpedance amplifier circuit and an operational amplifier circuit, which can convert the optical signal output by the microring resonator chip into an electrical signal and amplify it.

3. The wavelength division multiplexing wavelength demodulation system based on microring resonator according to claim 1, characterized in that: The mixing and filtering circuit comprises an analog multiplier circuit and a low-pass filtering circuit. The analog multiplier circuit realizes mixing of the sinusoidal oscillation modulation signal and the converted electrical signal, and the low-pass filtering circuit is used to filter out the high-frequency components after mixing.

4. The wavelength division multiplexing wavelength demodulation system based on microring resonator according to claim 1, characterized in that: The micro-ring resonator is a racetrack type, the radius of the circular part is 25 μm, the length of the middle coupling part is 20 μm, and the coupling distance between the micro-ring resonator and the transmission waveguides at the input end and the download end is 300 nm.

5. The wavelength division multiplexing wavelength demodulation system based on microring resonator according to claim 1, characterized in that: The titanium nitride film is located 1 μm above the microring resonator, and the impedance of the titanium nitride film is 760Ω.

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