Fast and slow light conversion method and device based on thermal effect in optical microcavity

Abstract

The invention provides a fast and slow light conversion method and device based on a heat effect in an optical microcavity, and relates to the field of optical communication, and the method comprises the steps: coupling a single-film silicon dioxide micro-ring core cavity through a straight waveguide, and constructing an optical microcavity system; incident light is input into the straight waveguide of the optical micro-cavity system, is coupled into the micro-ring core cavity through evanescent waves between the straight waveguide and the micro-ring core cavity, and resonates in the micro-ring; the incident light comprises pump light and probe light; a heat effect is generated by adjusting the power of the pump light; through the generated heat effect, the temperature in the micro-ring core cavity is adjusted, the resonant frequency is changed, and fast and slow light adjustment of an optical signal is realized. The temperature in the microcavity is adjusted through the thermo-optic effect to change the propagation speed of an optical signal, so that fast and slow light conversion is realized, and the device is suitable for fast and slow light conversion application in optical communication and information processing systems.

Description

Technical Field

[0001] The present application relates to the field of optical communications, and in particular to a method and device for fast-slow light conversion based on thermal effects in an optical microcavity. Background Art

[0002] Optical resonant cavities use micro-nano structures to localize light fields. Due to their high quality factor and small mode volume, they have always been a hot topic in optical research and have made great progress. In the resonant cavity, the photomechanical effect can modulate the dynamic behavior of the mechanical oscillator, thereby changing the transmission or reflection characteristics of the resonant cavity, causing the resonant cavity to absorb more or less light signals at a certain frequency. As the pump field intensity increases, the number of photons in the cavity increases, and the significant enhancement of effective photomechanical coupling leads to a sharp change in the absorption and dispersion characteristics of the system. Under the resonance condition Ω=Ω m Under these conditions, an abnormal change in dispersion will occur at the transparent window, accompanied by the generation of the fast-slow light effect. When the phase of the input light increases, the group velocity decreases, which manifests as slow light. When the phase of the input light decreases, the group velocity increases, which manifests as fast light. This opens up new possibilities in many fields such as high-precision sensing, quantum information processing, and optical signal processing.

[0003] Since the induced transparency of the optomechanical system is achieved through radiation-pressure coupling, and the light field of sufficient intensity will also cause the microcavity to vibrate mechanically, this will result in a higher light field density in the microcavity. Due to the ultra-high quality factor and small mode volume of the microcavity, the heat generated by cavity absorption loss can only be dissipated through the tiny surface, which leads to a temperature change in the cavity that cannot be ignored. The thermal broadening effect and light absorption will cause the temperature to increase, resulting in changes in the physical size and refractive index of the resonant cavity. These changes will change the resonant frequency, thereby tuning the fast and slow light. Summary of the invention

[0004] The purpose of the present invention is to provide a fast-slow light conversion method based on thermal effect in an optical microcavity in order to solve the problem that the existing fast-slow light adjustment method does not take into account the temperature change caused by thermal effect.

[0005] The above-mentioned purpose of the present application is achieved through the following technical solutions:

[0006] S1: A single-film silica micro-ring core cavity is coupled through a straight waveguide to construct an optical micro-cavity system;

[0007] S2: Input the incident light into the straight waveguide of the optical microcavity system, couple the incident light into the microring core cavity through the evanescent wave between the straight waveguide and the microring core cavity, and resonate in the microring; the incident light includes: a frequency of ω L The pump light and frequency are ω p The detection light;

[0008] S3: Generate thermal effect by adjusting the power of pump light;

[0009] S4: Through the generated thermal effect, the temperature inside the micro-ring core cavity is adjusted, the resonant frequency is changed, and the precise conversion of the optical signal from slow light to fast light is achieved.

[0010] Optionally, step S2 includes:

[0011] The cavity mode eigenfrequency of the optical microcavity is ω c , the intrinsic line width is κ0;

[0012] The optical microcavity passes through the fiber tapered waveguide at a frequency of ω L The control light and frequency are ω p Driven by the probe light, the excited cavity mode and the intrinsic mechanical frequency are Ω m The mechanical oscillators interact with each other.

[0013] Optionally, step S3 includes:

[0014] The incident light is input from the input end of the straight waveguide, coupled into the micro-ring core cavity, and output from the output end of the straight waveguide. The dynamic equation of the thermal effect of this process is:

[0015]

[0016] Where Δ0 = ω L -ω c is the frequency detuning between the pump field and the cavity mode; is the resonant frequency drift coefficient caused by temperature change; ΔT represents the thermal effect change of the system, ηΔT is the frequency shift of the thermally induced optical cavity resonance; Gx is the frequency shift caused by optomechanical interaction; the total attenuation rate of the cavity κ=κ0+κ ex , κ0 and κ ex are the intrinsic attenuation rate and external coupling attenuation rate between the cavity and the straight waveguide, respectively; a represents the amplitude of the light field in the cavity; and represent the normalized amplitudes of the pump field and the probe field, respectively, and P L and P P denote the power of the pump field and the detection field respectively; m denotes the effective mass; x denotes the mechanical displacement; Γ m ,Ω m are the intrinsic mechanical attenuation rate and resonant frequency of the mechanical oscillator, respectively; represents the reduced Planck constant; G represents the optomechanical coupling rate; S represents the heating rate per photon; γ th is the thermal relaxation rate of the resonant cavity; Ω = ω p -ω c is the frequency detuning between the probe field and the cavity field mode.

[0017] Optionally, step S3 further includes:

[0018] make ΔT=ΔT0+δΔT;

[0019]

[0020] Among them, δa, δx and δΔT represent perturbation terms; and ΔT0 represent the steady-state values ​​of the optical, mechanical, and thermal modes; is the effective detuning amount;

[0021] Under the condition that the amplitude of the detection field of the optical microcavity system is much smaller than the amplitude of the control field, that is, ε p <<ε l , combined with the perturbation method, the steady-state solution of the optical microcavity system is determined.

[0022] Optionally, the steady-state solution of the optical microcavity system is:

[0023]

[0024] in, represents the analytical solution of the first-order upper sideband; i represents an imaginary number;

[0025] Optionally, step S4 further includes:

[0026] According to the input-output relationship get Among them, S out Represents the output of the spectrum, S in represents the input of the spectrum, represents the analytical solution of the first-order lower sideband;

[0027] Only the first-order upper sideband e is considered -iΩt According to the definition of transmittance, the transmittance of the detection field is:

[0028] According to the definition of group velocity, the group delay τ of the transmitted light is obtained g for: arg(t p ) represents the transmission spectrum t p The phase of τ g =dargtpdΩΩ=Ωm represents the first-order derivative of the phase with respect to the frequency Ω at Ω=Ωm.

[0029] A fast-slow light conversion device based on thermal effect in an optical microcavity, the device comprising: a light source and an optical microcavity; the optical microcavity comprising: a micro-ring core cavity and a straight waveguide;

[0030] The light source is connected to a straight waveguide; the straight waveguide is coupled with the micro-ring core cavity through a potential wave coupling mechanism;

[0031] The light source is used to provide a frequency of ω L The pump light and frequency are ω p The detection light;

[0032] The straight waveguide is used to guide the input and output of optical signals, and comprises an input end and an output end.

[0033] Optionally, the straight waveguide is made of single-mode silica material; the micro-ring core cavity is made of single-film silica material

[0034] The beneficial effects of the technical solution of this application are as follows:

[0035] Construct an optical microcavity system with a straight waveguide coupled to a microring core cavity; by adjusting the power P of the pump light incident on the straight waveguide L , generating thermal effects, adjusting the temperature in the micro-ring core cavity, changing the resonant frequency, and realizing the fast and slow optical regulation of the optical signal. The influence of thermal effects in the micro-cavity on the propagation speed of the optical signal is analyzed to realize the flexible tuning of the optical signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present application will be further described below with reference to the accompanying drawings and embodiments, in which:

[0037] Figure 1 is a step diagram in an embodiment of the present application;

[0038] Figure 2 Schematic diagram of the structure of a silica micro-ring core cavity coupled with a straight waveguide in an embodiment of the present application;

[0039] Figure 3 The silicon dioxide micro-ring core cavity coupled with the straight waveguide in the embodiment of the present application is under the resonance condition Ω=Ω m The delay variation curve below. DETAILED DESCRIPTION

[0040] In order to have a clearer understanding of the technical features, purposes and effects of the present application, the specific implementation methods of the present application are now described in detail with reference to the accompanying drawings.

[0041] The embodiments of the present application provide a fast-slow light conversion method based on thermal effects in an optical microcavity.

[0042] Please refer to Figure 1 , Figure 1 1 is a step diagram of a fast-slow light conversion method based on thermal effect in an optical microcavity in an embodiment of the present application, comprising:

[0043] S1: A single-film silica micro-ring core cavity is coupled through a straight waveguide to construct an optical micro-cavity system;

[0044] S2: Input the incident light into the straight waveguide of the optical microcavity system, couple the incident light into the microring core cavity through the evanescent wave between the straight waveguide and the microring core cavity, and resonate in the microring; the incident light includes: a frequency of ω L The pump light and frequency are ω p The detection light;

[0045] Step S2 includes:

[0046] The cavity mode eigenfrequency of the optical microcavity is ω c , the intrinsic line width is κ0;

[0047] The optical microcavity passes through the fiber tapered waveguide at a frequency of ω L The control light field and frequency are ω p Driven by the detection light field, the excited cavity mode and the intrinsic mechanical frequency are Ω m The mechanical oscillators interact with each other.

[0048] S3: Generate thermal effect by adjusting the power of pump light;

[0049] Step S3 includes:

[0050] The incident light is input from the input end of the straight waveguide, coupled into the micro-ring core cavity, and output from the output end of the straight waveguide. The dynamic equation of the thermal effect of this process is:

[0051]

[0052] Where Δ0 = ω L -ω c is the frequency detuning between the pump field and the cavity mode; is the resonant frequency drift coefficient caused by temperature change; ΔT represents the thermal effect change of the system, ηΔT is the frequency shift of the thermally induced optical cavity resonance; Gx is the frequency shift caused by the optomechanical interaction; the total attenuation rate of the cavity k = k0 + k ex , κ0 and κ ex are the intrinsic attenuation rate and external coupling attenuation rate between the cavity and the straight waveguide, respectively; a represents the amplitude of the light field in the cavity; and represent the normalized amplitudes of the pump field and the probe field, respectively, and P L and P P denote the power of the pump field and the detection field respectively; m denotes the effective mass; x denotes the mechanical displacement; Γ m ,Ω m are the intrinsic mechanical attenuation rate and resonant frequency of the mechanical oscillator, respectively; represents the reduced Planck constant; G represents the optomechanical coupling rate; S represents the heating rate per photon; γ th is the thermal relaxation rate of the resonant cavity; Ω = ω p -ω c is the frequency detuning between the probe field and the cavity field mode.

[0053] Specifically, thermal effects will occur during the coupling process. The influences brought about by the thermal effects include changes in the effective refractive index of the material due to temperature changes, namely the thermo-optical effect; and changes in the size of the microcavity due to high heat in the cavity, namely thermal expansion.

[0054] Step S3 also includes:

[0055] make ΔT=ΔT0+δΔT;

[0056]

[0057] Among them, δa, δx and δΔT represent perturbation terms; and ΔT0 represent the steady-state values ​​of the optical, mechanical, and thermal modes; is the effective detuning amount;

[0058] Under the condition that the amplitude of the detection field of the optical microcavity system is much smaller than the amplitude of the control field, that is, ε p <<ε l , combined with the perturbation method, the steady-state solution of the optical microcavity system is determined.

[0059] The steady-state solution of the optical microcavity system is:

[0060]

[0061] in, represents the analytical solution of the first-order upper sideband; i represents an imaginary number;

[0062] S4: Through the generated thermal effect, the temperature inside the micro-ring core cavity is adjusted, the resonant frequency is changed, and the precise conversion of the optical signal from slow light to fast light is achieved.

[0063] Step S4 also includes:

[0064] According to the input-output relationship get Among them, S out Represents the output of the spectrum, S in represents the input of the spectrum, represents the analytical solution of the first-order lower sideband;

[0065] Only the first-order upper sideband e is considered -iΩtAccording to the definition of transmittance, the transmittance of the detection field is:

[0066] According to the definition of group velocity, the group delay τ of the transmitted light is obtained g for: arg(t p ) represents the transmission spectrum t p The phase of τ g =dargtpdΩΩ=Ωm represents the first-order derivative of the phase with respect to the frequency Ω at Ω=Ωm.

[0067] Specifically, when light is coupled into the microcavity, the microcavity material absorbs photons, causing the temperature inside the microcavity to change, and then produces a thermal effect through the thermal light and thermal expansion mechanism of the material, resulting in changes in the physical size and refractive index of the resonant cavity. These changes will change the resonant frequency, thereby tuning the fast and slow light. In this process, when the phase of the input light increases, the group velocity decreases, and it appears as slow light. When the phase of the input light decreases, the group velocity increases, and it appears as fast light.

[0068] Specifically, a light field of sufficient intensity in an optical microcavity will cause the temperature of the microcavity to fluctuate, which in turn leads to a change in the refractive index of the microcavity; and the movement of the microcavity resonance frequency caused by the change in the microcavity temperature, in turn, affects the coupling efficiency. As the pump field intensity increases, the number of photons in the cavity increases, and the significant enhancement of effective optical-mechanical coupling leads to a sharp change in the absorption and dispersion characteristics of the system.

[0069] Specifically, the optical microcavity is a single-film silica microring core cavity coupled with a straight waveguide. It adjusts the temperature inside the microcavity through the thermo-optical effect to change the propagation speed of the optical signal. It is suitable for fast-slow light conversion applications in optical communications and information processing systems.

[0070] This verification is carried out by numerical simulation. The main parameters used in the simulation are: the effective mass of the microring is m = 1.7 × 10 -10 g, the intrinsic attenuation rate between the cavity and the waveguide is k0 = 2π × 15MHz, and the external coupling attenuation rate is k wx =2π×15MHz, the coupling strength is G=2π×1.52×10 17 Hz / m, the resonant frequency of the mechanical oscillator is Ω m =2π×19.8MHz, the intrinsic mechanical attenuation rate of the mechanical oscillator is Γ m =2π×28.3kHz, the thermal relaxation rate of the resonant cavity is γ th =90kHz, the heating rate per photon is S = 1.2×10 4 K / s, the resonant frequency drift coefficient caused by temperature change is η=2π×1.71GHz / K.

[0071] Under the resonance condition Ω=Ω m Under these conditions, the abnormal change of dispersion leads to the fast and slow light effect. Figure 3 It can be seen that in the absence of temperature influence, the probe light is always in the slow light state. This phenomenon shows that under ideal conditions, the dispersion characteristics remain stable. However, when the temperature variable is introduced for investigation, the situation changes significantly. In particular, when the pump power range is between 0.1mW and 0.4mW, the group delay evolution process of the probe light changes significantly. The influence of temperature causes the probe light to gradually transition from the slow light state to the fast light state, and finally presents as fast light. This dynamic tuning process from slow light to fast light shows that temperature is not only an external disturbance factor, but also can achieve tunable switching of light propagation characteristics through precise control. This phenomenon has important potential applications in the field of optical switch technology. In practical applications, by controlling the pump power and temperature, the optical signal can be precisely controlled, making the optical switch more flexible and controllable. This not only improves the efficiency and stability of optical communication systems, but also provides new design ideas for future photonic integrated circuits.

[0072] A fast-slow light conversion device based on thermal effect in an optical microcavity, the device comprising: a light source and an optical microcavity; the optical microcavity comprising: a micro-ring core cavity and a straight waveguide;

[0073] The light source is connected to the straight waveguide; the straight waveguide and the micro-ring core cavity are coupled through a potential wave coupling mechanism;

[0074] Specifically, the microring core cavity and the straight waveguide are coupled through the potential wave coupling mechanism. This structural design can ensure that the optical signal can achieve efficient resonance in the microring and enhance the influence of thermal effects on the speed of light propagation.

[0075] The light source is used to provide a frequency of ω L The pump light and frequency are ω p The detection light;

[0076] A straight waveguide is used to guide the input and output of optical signals, including the input end and the output end.

[0077] Specifically, the straight waveguide uses single-mode silica material to reduce optical loss and improve signal transmission efficiency. The optical signal enters the straight waveguide from the input end, enters the micro-ring core cavity through the potential wave coupling mechanism for resonance, and finally outputs from the output end. Through this design, efficient regulation of optical signals can be achieved.

[0078] The straight waveguide is made of single-mode silica; the micro-ring core cavity is made of single-film silica.

[0079] In summary, the present invention provides a fast-slow light conversion device and method based on thermal effects in an optical microcavity. The device includes a single-film silica microring cavity coupled to a waveguide, and its overall design takes into account both compactness and high efficiency. Specifically, pump light and probe light enter the straight waveguide through the input end of the waveguide. When the optical signal propagates in the straight waveguide, it enters the microring cavity for resonance through the potential wave coupling mechanism between the waveguide and the resonator. In the microring cavity, the optical signal interacts with the medium during multiple cyclic reflections, producing a significant slow light or fast light effect. Finally, the tuned optical signal is output through the output end. By adjusting the power and frequency of the pump field, the optical signal can be accurately converted from slow light to fast light. This tuning process not only depends on the control of the pump field, but also is regulated by the influence of temperature on dispersion and group delay in the microring cavity. Therefore, by accurately controlling the temperature, the tuning process of the optical signal can be further optimized and the performance of the device can be improved. The fast-slow light conversion device of the present invention has broad application prospects in many fields. First, in terms of optical signal processing, this device can be used to delay and accelerate optical pulses, thereby optimizing the performance of optical communication systems. Secondly, in optical switching technology, the response speed and reliability of optical switches can be improved by quickly tuning and switching optical signals. By deeply studying the impact of temperature on dispersion and group delay, the present invention further optimizes the application of fast and slow optical effects. This research not only promotes the development of fast and slow optical conversion devices in optical switching technology, but also brings new breakthroughs and more innovative possibilities to optical communication and information processing technology. Ultimately, this fast and slow optical conversion device based on thermal effects in optical microcavities and its method will provide strong support for the development of next-generation photonic technology.

[0080] The above are only exemplary embodiments of the present disclosure and cannot be used to limit the scope of the present disclosure. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the disclosure of the specification and the truth of practice, those skilled in the art will easily think of other embodiments of the present disclosure.

[0081] This application is intended to cover any variation, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the art not described in the present disclosure. The description and examples are to be regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A fast-slow light conversion method based on thermal effect in an optical microcavity, characterized in that: The method comprises the following steps: S1: A single-film silica micro-ring core cavity is coupled through a straight waveguide to construct an optical micro-cavity system; S2: Input the incident light into the straight waveguide of the optical microcavity system, couple the incident light into the microring core cavity through the evanescent wave between the straight waveguide and the microring core cavity, and resonate in the microring; the incident light includes: a frequency of ω L The pump light and frequency are ω p The detection light; S3: Generate thermal effect by adjusting the power of pump light; S4: Through the generated thermal effect, the temperature inside the micro-ring core cavity is adjusted, the resonant frequency is changed, and the precise conversion of the optical signal from slow light to fast light is achieved.

2. The method for fast-slow light conversion based on thermal effect in an optical microcavity according to claim 1, characterized in that: Step S2 includes: The cavity mode eigenfrequency of the optical microcavity is ω c , the intrinsic line width is κ0; The optical microcavity passes through the fiber tapered waveguide at a frequency of ω L The control light and frequency are ω p Driven by the probe light, the excited cavity mode and the intrinsic mechanical frequency are Ω m The mechanical oscillators interact with each other.

3. The method for fast-slow light conversion based on thermal effect in an optical microcavity according to claim 2, characterized in that: Step S3 includes: The incident light is input from the input end of the straight waveguide, coupled into the micro-ring core cavity, and output from the output end of the straight waveguide. The dynamic equation of the thermal effect of this process is: Where Δ0 = ω L -ω c is the frequency detuning between the pump field and the cavity mode; is the resonant frequency drift coefficient caused by temperature change; ΔT represents the thermal effect change of the system, ηΔT is the frequency shift of the thermally induced optical cavity resonance; Gx is the frequency shift caused by optomechanical interaction; the total attenuation rate of the cavity κ=κ0+κ ex , κ0 and κ ex are the intrinsic attenuation rate and external coupling attenuation rate between the cavity and the straight waveguide, respectively; a represents the amplitude of the light field in the cavity; and represent the normalized amplitudes of the pump field and the probe field, respectively, and P L and P P denote the power of the pump field and the detection field respectively; m denotes the effective mass; x denotes the mechanical displacement; Γ m ,Ω m are the intrinsic mechanical attenuation rate and resonant frequency of the mechanical oscillator, respectively; represents the reduced Planck constant; G represents the optomechanical coupling rate; S represents the heating rate per photon; γ th is the thermal relaxation rate of the resonant cavity; Ω = ω p -ω c is the frequency detuning between the probe field and the cavity field mode.

4. The method for fast-slow light conversion based on thermal effect in an optical microcavity according to claim 3, characterized in that: Step S3 also includes: Let ΔT = ΔT0 + δΔT; Among them, δa, δx and δΔT represent perturbation terms; and ΔT0 represent the steady-state values ​​of the optical, mechanical, and thermal modes; is the effective detuning amount; Under the condition that the amplitude of the detection field of the optical microcavity system is much smaller than the amplitude of the control field, that is, ε p <<ε l , combined with the perturbation method, the steady-state solution of the optical microcavity system is determined.

5. The method for fast-slow light conversion based on thermal effect in an optical microcavity according to claim 4, characterized in that: The steady-state solution of the optical microcavity system is: in, represents the analytical solution of the first-order upper sideband; i represents an imaginary number; 6. The method for fast-slow light conversion based on thermal effect in an optical microcavity according to claim 3, characterized in that: Step S4 also includes: According to the input-output relationship get Among them, S out Represents the output of the spectrum, S in represents the input of the spectrum, represents the analytical solution of the first-order lower sideband; Only the first-order upper sideband e is considered -iΩt According to the definition of transmittance, the transmittance of the detection field is: According to the definition of group velocity, the group delay τ of the transmitted light is obtained g for: arg(t p ) represents the transmission spectrum t p The phase of τ g =dargtpdΩΩ=Ωm represents the first-order derivative of the phase with respect to the frequency Ω at Ω=Ωm.

7. A fast-slow light conversion device based on thermal effect in an optical microcavity, used to implement a fast-slow light conversion method based on thermal effect in an optical microcavity as claimed in any one of claims 1 to 6, characterized in that: The device comprises: a light source and an optical microcavity; the optical microcavity comprises: a micro-ring core cavity and a straight waveguide; The light source is connected to a straight waveguide; the straight waveguide is coupled to the micro-ring core cavity through a potential wave coupling mechanism; The light source is used to provide a frequency of ω L The pump light and frequency are ω p The detection light; The straight waveguide is used to guide the input and output of optical signals, and comprises an input end and an output end.

8. The fast-slow light conversion device based on thermal effect in an optical microcavity according to claim 7, characterized in that: The straight waveguide is made of single-mode silica material; the micro-ring core cavity is made of single-film silica material.

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