A high-Q microdisk resonator with active mode selection

Abstract

The present invention discloses a high-Q microdisk resonator, a bandpass filter and a bandstop filter for active mode selection. The high-Q microdisk resonator for active mode selection comprises: a microdisk resonant cavity with adiabatic holes, a heating electrode, and a first single-mode waveguide and a second single-mode waveguide, a first tapered waveguide and a second tapered waveguide, a first curved waveguide and a second curved waveguide symmetrically distributed about a third curved waveguide; incident light is incident from the first single-mode waveguide, light that meets the resonant frequency in the incident light is coupled into the microdisk resonant cavity, and light that does not meet the resonant frequency is output from the second single-mode waveguide; the heating electrode covers the surface of the microdisk resonant cavity, and adiabatic holes are set on the microdisk resonant cavity for actively exciting a specific mode, and ensuring that the specific mode is adiabatically transmitted in the microdisk resonator. The problem of easily causing multi-mode competition, gain saturation and mode hopping is solved, and the adiabatic transmission of the excited specific mode in the microdisk resonant cavity is achieved, which reduces the beneficial effect of scattering loss.

Description

Technical Field

[0001] The present invention belongs to the field of optical communication, and more specifically, relates to a high-Q micro-disk resonator, a bandpass filter and a bandstop filter for active mode selection. Background Art

[0002] For an optical resonant cavity, the Q value indicates the sharpness of the resonance peak relative to the center frequency, and describes the ability of the resonant cavity to store and confine light. In many scenarios that require a narrow filter window or a strong resonance enhancement effect, a high Q value is often required. According to the light confinement mechanism, optical resonants can be mainly divided into FP resonant cavities, photonic crystal resonant cavities, and whispering gallery mode microcavities. Among them, the whispering gallery mode (WGM) microcavity has a higher Q value, strong integration, and low cost. It is a key component for making filters, optoelectronic oscillators, optical caches, sensors and other devices.

[0003] Whispering gallery mode microresonators with small mode volume and high quality Q factor can greatly enhance the interaction between light and matter and are an ideal platform for studying various optical phenomena. So far, whispering gallery mode microresonators have been widely used in various research fields, including cavity optics, cavity quantum electrodynamics, nonlinear optics and optical sensing.

[0004] Due to multiple spatial degrees of freedom, whispering gallery modes supported in large microcavities usually exhibit complex mode profiles and large mode density. When whispering gallery mode microresonators are applied to low-threshold lasers, their dense modes easily induce multimode lasing, leading to mode competition, which in turn produces adverse effects such as gain saturation and mode hopping in practical applications. Summary of the invention

[0005] In view of the defects of the related art, the purpose of the present invention is to provide a high-Q microdisk resonator, a bandpass filter and a bandstop filter with active mode selection, aiming to solve the problem of easily causing multi-mode lasers, leading to mode competition, gain saturation and mode hopping.

[0006] To achieve the above objectives, the invention adopts the following technical solutions.

[0007] In a first aspect, the present invention provides a high-Q microdisk resonator with active mode selection, comprising: a microdisk resonant cavity, a heating electrode, and a first single-mode waveguide and a second single-mode waveguide, a first tapered waveguide and a second tapered waveguide, a first curved waveguide and a second curved waveguide symmetrically distributed about a third curved waveguide;

[0008] The incident light is incident from the first single-mode waveguide, passes through the first tapered waveguide and the first curved waveguide in sequence, and is coupled in the region of the third curved waveguide, the light of the incident light that meets the resonance frequency is coupled into the micro-disk resonant cavity, and the light that does not meet the resonance frequency is transmitted to the second single-mode waveguide through the second curved waveguide and the second tapered waveguide in sequence to be output;

[0009] The heating electrode covers the surface of the micro-disk resonant cavity and is used for heating to change the resonant frequency of the waveguide and actively excite a specific mode;

[0010] Adiabatic holes are provided on the micro-disk resonant cavity to ensure adiabatic transmission of the specific mode in the micro-disk resonator.

[0011] Optionally, the adiabatic hole digging is determined according to a hole digging curve function, and the adiabatic hole digging satisfies that the waveguide width increases linearly along the radial direction and that the half angle of the gradient width waveguide is less than or equal to the mode diffusion half angle, thereby ensuring adiabatic transmission of the excited specific mode;

[0012] Wherein, the hole digging curve function is:

[0013]

[0014]

[0015] x inner (m)=(RK·(α(i)-θ0))·cos(α(i));

[0016] y inner (m)=(RK·(α(i)-θ0))·sin(α(i));

[0017] Where K is the linear coefficient, theta0 is the starting angle, R is the radius of the microdisk resonant cavity, h2, h1 refers to the radial distance between the edge of the adiabatic hole and the edge of the microdisk resonant cavity, i is the differential angle between the hole and the center of the microdisk resonant cavity; x, y are the horizontal and vertical coordinates of each point on the hole-digging curve;

[0018] Optionally, the third curved waveguide region adopts a weak tapered gap coupling form; the coupling waveguide matches the refractive index of a specific mode of the micro-disk resonant cavity.

[0019] Optionally, the heating electrode is disposed on a side of the micro-disk resonant cavity away from the third curved waveguide.

[0020] Optionally, the first tapered waveguide, the second tapered waveguide, the first curved waveguide, the second curved waveguide and the third curved waveguide are all multimode waveguides;

[0021] The first single-mode waveguide, the second single-mode waveguide, the first tapered waveguide, the second tapered waveguide, the first curved waveguide, the second curved waveguide and the third curved waveguide are any one of a strip waveguide, a ridge waveguide and a multilayer waveguide.

[0022] Optionally, the first single-mode waveguide, the second single-mode waveguide, the first tapered waveguide, the second tapered waveguide, the first curved waveguide, the second curved waveguide and the third curved waveguide are all made of any one of silicon on insulator, lithium niobate, silicon nitride, indium phosphide and gallium arsenide.

[0023] Optionally, a compensation device is also included for performing feedback compensation for the resonance wavelength drift of the micro-disk resonant cavity.

[0024] In a second aspect, the present invention provides a bandpass filter, wherein the bandpass filter adopts the high-Q microdisk resonator with active mode selection as described in any one of the first aspects.

[0025] In a third aspect, the present invention provides a band-stop filter, wherein the band-stop filter adopts the high-Q microdisk resonator with active mode selection as described in any one of the first aspects.

[0026] The above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0027] 1. The high-Q microdisk resonator with active mode selection provided by the present invention uses the high-Q characteristics of a large-size microdisk to enable the microwave signal to obtain a larger delay and a narrower bandwidth, increase the power difference between the starting mode and the sub-maximum mode, and then use the coupling area to specifically excite a certain mode, and then cooperate with the adiabatic hole digging with a gradual change in the waveguide width, so that the specific mode excited in the microdisk is adiabatically transmitted in the microdisk, so that the microwave signal finally obtains stable single-mode oscillation.

[0028] 2. The high-Q microdisk resonator with active mode selection provided by the present invention can confine most of the fundamental mode light field inside the waveguide, reduce the interaction between the light field and the side wall, thereby reducing the scattering loss caused by the roughness of the side wall and improving the intrinsic Q value of the microring resonator.

[0029] 3. The high-Q microdisk resonator with active mode selection provided by the present invention adopts weak tapered gap coupling to meet the curvature matching of the coupled curved waveguide and the microdisk resonant cavity to meet the effective refractive index matching of the mode. The excitation efficiency of the active selection mode is higher and it is easier to achieve adiabatic transmission of the mode.

[0030] 4. The high-Q microdisk resonator provided by the present invention has great advantages in integration with other devices and can be used in bandpass or bandstop filters. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic structural diagram of a high-Q microdisk resonator with active mode selection provided in Embodiment 1 of the present invention;

[0032] Figure 2 Schematic diagram of four positions of adiabatic holes in a micro-disk resonant cavity provided in the first embodiment of the present invention;

[0033] Figure 3 The distribution diagram of different light field modes in the micro-disk resonant cavity provided by the first embodiment of the present invention. In the above drawings, the same reference numerals are used to represent the same components or structures, wherein:

[0034] 1-first single-mode waveguide; 2-first tapered waveguide; 3-first curved waveguide; 4-third curved waveguide; 5-second curved waveguide; 6-second tapered waveguide; 7-second single-mode waveguide; 8-microdisk resonant cavity with adiabatic hole design. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] The contents involved in the above embodiment are described below in conjunction with a preferred embodiment.

[0037] Embodiment 1

[0038] Figure 1 A schematic structural diagram of a high-Q microdisk resonator with active mode selection provided in Example 1 of the present invention.

[0039] like Figure 1 As shown, an active mode selective high-Q microdisk resonator comprises: a microdisk resonant cavity 8, a heating electrode (not shown), and a first single-mode waveguide 1 and a second single-mode waveguide 7, a first tapered waveguide 2 and a second tapered waveguide 6, a first curved waveguide 3, and a second curved waveguide 5 symmetrically distributed about a third curved waveguide 4;

[0040] The incident light is incident from the first single-mode waveguide 1, passes through the first tapered waveguide 2 and the first curved waveguide 3 in sequence, and is coupled in the region of the third curved waveguide 4. The light that meets the resonance frequency in the incident light is coupled into the micro-disk resonant cavity 8, and the light that does not meet the resonance frequency passes through the second curved waveguide 5 and the second tapered waveguide 6 in sequence, and is transmitted to the second single-mode waveguide 7 for output;

[0041] The heating electrode covers the surface of the micro-disk resonant cavity 8 and is used to heat and change the resonant frequency of the waveguide to actively excite a specific mode;

[0042] Adiabatic holes are provided on the micro-disk resonant cavity 8 to ensure adiabatic transmission of the specific mode in the micro-disk resonator.

[0043] Optionally, the heating electrode is disposed on a side of the micro-disk resonant cavity 8 away from the third curved waveguide 4 .

[0044] The incident light is transmitted in each section of the waveguide. When passing through the area of ​​the third curved waveguide 4, coupling is performed to couple the light that meets the resonant frequency into the micro-disk resonant cavity 8. After the incident light is selected by the coupling area, a light spot of a specific mode is output; the heating electrode covering the edge of the micro-disk resonant cavity 8 is heated by an electrical signal, causing the refractive index of the waveguide material to change, thereby realizing the tuning of the resonant wavelength, thereby realizing the target mode selection, exciting a specific mode, and other modes will not be emitted. Furthermore, by constructing a specific function to dig a hole on the micro-disk resonant cavity 8, an adiabatic hole is set so that the specific mode can be adiabatically transmitted after the micro-disk resonant cavity 8 is dug, while other modes are suppressed.

[0045] The size of the microdisk resonant cavity selected in this embodiment is relatively large, which can ensure that the radiation loss and sidewall scattering loss of the light field during transmission are very low. When the size of the microdisk resonant cavity is small, part of the light field will leak directly outside the side wall of the cavity. As the radius of the microdisk resonant cavity gradually increases, the light field is better confined inside the microdisk resonant cavity, and the distance from the side wall of the microdisk resonant cavity gradually increases, reducing the scattering loss caused by the roughness of the side wall. As the radius of the microdisk resonant cavity increases, the effective refractive index and group refraction first increase rapidly, then the rate of increase becomes slower and slower, and finally almost stabilizes, indicating that as the size of the microdisk resonant cavity increases, the light field can be better confined to propagate in the cavity, weakening the influence of radiation loss, but when the size increases to a certain extent, the light field is basically confined in the microdisk resonant cavity, and the increase in the size of the microdisk resonant cavity is no longer obvious.

[0046] Since the microdisk resonant cavity has only one side wall, the light field of the mode in the microdisk resonant cavity contacts the side wall less than that of a microring of the same size. Therefore, its scattering loss and radiation loss have less impact on the Q value of the microdisk resonant cavity, and its Q value is theoretically higher.

[0047] The microdisk structure consists of a microdisk resonant cavity 8 and a curved coupled waveguide. In the coupling region, the microdisk resonant cavity is concentric with the third curved waveguide 4, and their radii are R1 and R2 respectively. The effective refractive index value of the active selection mode in the microdisk is n1, and the effective refractive index of the fundamental mode of the coupled waveguide with a specific width w1 is n2, so that it satisfies n1*R1=n2*R2. Therefore, through this design, the refractive index matching of the fundamental mode in the coupled waveguide and the specific mode in the microdisk can be achieved, and the specific mode can be excited.

[0048] Optionally, the adiabatic hole digging is determined according to a hole digging curve function, and the adiabatic hole digging satisfies that the waveguide width increases linearly along the radial direction and that the half angle of the gradient width waveguide is less than or equal to the mode diffusion half angle, thereby ensuring adiabatic transmission of the excited specific mode;

[0049] Wherein, the hole digging curve function is:

[0050]

[0051]

[0052] x inner (m)=(RK·(α(i)-θ0))·cos(α(i));

[0053] y inner (m)=(RK·(α(i)-θ0))·sin(α(i));

[0054] Where K is the linear coefficient, theta0 is the starting angle, R is the radius of the microdisk resonant cavity, h2 and h1 refer to the radial distance between the edge of the adiabatic hole and the edge of the microdisk resonant cavity, i is the differential angle between the hole and the center of the microdisk resonant cavity; x and y are the horizontal and vertical coordinates of each point on the hole-digging curve.

[0055] Since the microdisk resonator has only one sidewall, it is easy to excite high-order modes when the mode is transmitted in the microdisk resonator. The high-order modes not only have larger losses than the fundamental mode, but also have a greater impact on the phase noise of the optoelectronic oscillator. Therefore, it is very difficult to propagate a simple pure mode in the microdisk resonator. A curve equation with a linear gradient along the central waveguide width of the microdisk resonator is constructed, and adiabatic transmission of a specific mode in the microdisk resonator is achieved through the hole-digging curve design.

[0056] By constructing a hole-digging curve function, the position of the adiabatic hole on the micro-disk resonant cavity is determined so that the waveguide width increases linearly along the radial direction. The optimal width gradient rate can be obtained to satisfy the half-angle of the optimal gradient width waveguide less than or equal to the diffusion half-angle of the excitation mode, thereby achieving tuning of the resonant wavelength of the micro-disk resonant cavity and ensuring the adiabatic transmission of the specific mode excited.

[0057] Furthermore, the gradient curvature of the waveguide width of the high-Q microdisk resonator using active mode selection can achieve adiabatic transmission in a specific mode at the fastest rate, so that the mode transmission in the waveguide always meets: the half angle of the gradient width waveguide is less than or equal to the mode diffusion half angle, thereby ensuring adiabatic transmission of the specific mode, not exciting other modes, reducing mode crosstalk, and improving the device Q value. Furthermore, through a specific hole-digging curve, the specific mode that meets the refractive index matching excitation in the coupling region can be guaranteed to be adiabatic after passing through the hole-digging curve, thereby achieving single mode transmission in the microdisk.

[0058] Specifically, the selection of the adiabatic hole position, through a specific hole-digging curve, ensures that the specific mode at the excitation point that satisfies the refractive index matching in the coupling region can pass through the hole-digging curve to ensure the adiabatic transmission of the mode, thereby achieving single mode transmission in the microdisk. In order to further improve the performance of the microdisk, the holes at four positions were analyzed, such as Figure 2 As shown. The adiabatic hole digging curve has four positions at 0° digging (such as Figure 2 In a), dig a hole at 90° (such as Figure 2 b), dig a hole at 180° (such as Figure 2 c), dig a hole at 270° (such as Figure 2 d), by combining FDTD and MATLAB software distribution, when the hole position is located at Figure 2 In the middle b, that is, at the 90° position, the purity of the specific mode is higher, the side mode suppression ratio is better, and the performance of the high-Q microdisk resonator is better. Therefore, in this embodiment, the adiabatic hole is set at 90°.

[0059] The high-Q microdisk resonator with active mode selection provided by the embodiment of the present invention adopts a large-size microdisk resonant cavity structure. The high-Q characteristics enable the microwave signal to obtain a larger delay and narrower bandwidth, increasing the power difference between the start-up mode and the sub-maximum mode; at the same time, the coupling region is used to excite a specific mode, and the adiabatic hole on the microdisk resonant cavity is used to make the excited specific mode adiabatically transmitted in the microdisk resonant cavity structure, so that the microwave signal finally obtains a stable single-mode oscillation. The problem of easily causing multi-mode lasers, leading to mode competition, gain saturation and mode hopping is solved, and the adiabatic transmission of the excited specific mode in the microdisk resonant cavity is achieved, which reduces the beneficial effect of scattering loss.

[0060] On the basis of the above embodiment, optionally, the third curved waveguide 4 region adopts a weak tapered gap coupling form; the refractive index of the coupling waveguide matches the specific mode of the micro-disk resonant cavity.

[0061] The coupling that occurs at the smallest gap in the coupling region is weakly taper. The incident light is incident from the input straight waveguide, and the light that meets the resonance frequency enters the microdisk resonant cavity in the curved waveguide in the form of weakly taper. The light that does not meet the resonance frequency is output through the output straight waveguide. By optimizing the width of the bus waveguide, it meets the refractive index matching of a specific excitation mode. The coupling part adopts the form of weakly taper gap coupling to meet the refractive index matching relationship between the coupling waveguide and the specific mode in the microdisk resonant cavity, making the excitation efficiency of the active selection mode higher, reducing the interaction between the light field and the side wall, reducing the scattering loss of the side wall of the microdisk resonant cavity, and increasing the Q value.

[0062] COMSOL was used to simulate the different order modes in the micro-disk resonant cavity with a radius of R = 500μm. The SOI micro-disk was analyzed with a waveguide thickness of 220nm and an etching depth of 150nm. The main energy width distribution of different modes in the whispering gallery micro-disk can be obtained: TE0: 3μm, TE1: 5μm, TE2: 7μm, TE3: 9μm, which provides help for the design of adiabatic holes. At the same time, the effective refractive index of different modes is simulated. When the refractive index matching is satisfied: n1*R1=n2*R2, the corresponding coupling waveguide widths are: w1=2.1μm, w1=1.75μm, w1=1.4μm, w1=1.05μm.

[0063] like Figure 3 As shown in the figure, the widths of different modes under a specific disk radius are obtained by simulation software COMSOL, where the width of the fundamental mode is L1, the width of the TE1 mode is L2, the width of the TE2 mode is L3, and the width of the TE4 mode is L4, which provides a theoretical basis for the location and size of our holes. At the same time, the refractive index of the over-coupling area is matched, and the specific curve hole is combined to make the excited specific mode adiabatically transmitted in the micro-disk. The two methods are combined to obtain a single-mode high-Q micro-disk, in which the coupled waveguide is weakly tapered gap coupled, and the absolute transition from the single-mode condition of SOI 0.5μm to the waveguide width matching the refractive index of the specific mode in the micro-disk is achieved. The coupling area is set as curved coupling, which satisfies the refractive index matching n1*R1=n2*R2, and satisfies the curvature of the coupled curved waveguide and the micro-disk resonant cavity to meet the effective refractive index matching of the mode. The excitation efficiency of this active selection mode is higher, thereby realizing the active selection of a specific mode in the micro-disk, and it is also easier to achieve adiabatic transmission of this mode.

[0064] Optionally, the first tapered waveguide 2, the second tapered waveguide 6, the first curved waveguide 3, the second curved waveguide 5 and the third curved waveguide 4 are all multimode waveguides;

[0065] The first single-mode waveguide 1, the second single-mode waveguide 7, the first tapered waveguide 2, the second tapered waveguide 6, the first curved waveguide 3, the second curved waveguide 5 and the third curved waveguide 4 are any one of a strip waveguide, a ridge waveguide and a multilayer waveguide.

[0066] Optionally, the first single-mode waveguide 1, the second single-mode waveguide 7, the first tapered waveguide 2, the second tapered waveguide 6, the first curved waveguide 3, the second curved waveguide 5 and the third curved waveguide 4 are all made of any one of silicon on insulator, lithium niobate, silicon nitride, indium phosphide and gallium arsenide.

[0067] Optionally, a compensation device (not shown) is further included to perform feedback compensation for the resonance wavelength drift of the micro-disk resonant cavity 8 .

[0068] Exemplarily, by compensating for the resonant wavelength drift of the micro-disk resonant cavity 8 through a subsequent algorithm, the instability caused by factors such as environmental jitter can be eliminated, thereby improving the performance stability of the high-Q micro-disk resonator with active mode selection.

[0069] Embodiment 2

[0070] On the basis of the above embodiments, the present invention provides a bandpass filter, wherein the bandpass filter adopts the high-Q microdisk resonator with active mode selection as described in any one of the above embodiments.

[0071] On the basis of the above embodiments, the present invention provides a band-stop filter, wherein the band-stop filter adopts the high-Q micro-disk resonator with active mode selection as described in any one of the above embodiments.

[0072] The high-Q-value microdisk resonator provided by the present invention has great advantages in integration with other devices and can be used in a bandpass or bandstop filter.

[0073] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-Q microdisk resonator with active mode selection, characterized in that include: A micro-disk resonant cavity, a heating electrode, and a first single-mode waveguide and a second single-mode waveguide, a first tapered waveguide and a second tapered waveguide, a first curved waveguide and a second curved waveguide symmetrically distributed about a third curved waveguide; The incident light is incident from the first single-mode waveguide, passes through the first tapered waveguide and the first curved waveguide in sequence, and is coupled in the region of the third curved waveguide, the light of the incident light that meets the resonance frequency is coupled into the micro-disk resonant cavity, and the light that does not meet the resonance frequency is transmitted to the second single-mode waveguide through the second curved waveguide and the second tapered waveguide in sequence to be output; The heating electrode covers the surface of the micro-disk resonant cavity and is used for heating to change the resonant frequency of the waveguide and actively excite a specific mode; Adiabatic holes are provided on the micro-disk resonant cavity to ensure adiabatic transmission of the specific mode in the micro-disk resonator.

2. The active mode selective high-Q microdisk resonator of claim 1, wherein: The adiabatic hole digging is determined according to a hole digging curve function, and the adiabatic hole digging satisfies that the waveguide width increases linearly along the radial direction and that the half angle of the gradient width waveguide is less than or equal to the mode diffusion half angle, thereby ensuring the adiabatic transmission of the excited specific mode; Wherein, the hole digging curve function is: x inner (m)=(RK·(α(i)-θ0))·cos(α(i)); y inner (m)=(RK·(α(i)-θ0))·sin(α(i)); Where K is the linear coefficient, θ0 is the starting angle, R is the radius of the microdisk resonant cavity, h2, h1 refer to the radial distance between the edge of the adiabatic hole and the edge of the microdisk resonant cavity, i is the differential angle between the hole and the center of the microdisk resonant cavity; x, y are the horizontal and vertical coordinates of each point on the hole-digging curve.

3. The active mode selective high-Q microdisk resonator of claim 1, wherein: The third curved waveguide region adopts a weak tapered gap coupling form; the coupling waveguide matches the refractive index of a specific mode of the micro-disk resonant cavity.

4. The active mode selective high-Q microdisk resonator of claim 1, wherein: The heating electrode is arranged on a side of the micro-disk resonant cavity away from the third curved waveguide.

5. The active mode selective high-Q microdisk resonator of claim 1, wherein: The first tapered waveguide, the second tapered waveguide, the first curved waveguide, the second curved waveguide and the third curved waveguide are all multimode waveguides; The first single-mode waveguide, the second single-mode waveguide, the first tapered waveguide, the second tapered waveguide, the first curved waveguide, the second curved waveguide and the third curved waveguide are any one of a strip waveguide, a ridge waveguide and a multilayer waveguide.

6. The active mode selective high-Q microdisk resonator of claim 5, wherein: The first single-mode waveguide, the second single-mode waveguide, the first tapered waveguide, the second tapered waveguide, the first curved waveguide, the second curved waveguide and the third curved waveguide are all made of any one of silicon on insulator, lithium niobate, silicon nitride, indium phosphide and gallium arsenide.

7. The active mode selective high-Q microdisk resonator of claim 1, wherein: The invention also comprises a compensation device for performing feedback compensation on the resonance wavelength drift of the micro-disk resonance cavity.

8. A bandpass filter, characterized in that: The bandpass filter adopts the high-Q microdisk resonator of active mode selection as described in any one of claims 1-7.

9. A band-stop filter, characterized in that: The band-stop filter uses the high-Q microdisk resonator with active mode selection as described in any one of claims 1-7.

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