阅读说明：本技术 一种环境稳定的超高品质因子光学微腔及其制备方法 (Environment-stable optical microcavity with ultrahigh quality factor and preparation method thereof ) 是由 沈晓钦 汪洋 于 2021-06-24 设计创作，主要内容包括：本发明公开了一种环境稳定的超高品质因子光学微腔及其制备方法。本发明的环境稳定的超高品质因子光学微腔是通过化学气相沉积法在回音壁模式光学微腔表面沉积硅烷偶联剂层后得到,所述回音壁模式光学微腔的表面经过化学修饰从而形成不受环境影响的稳定结构。其中,硅烷偶联剂为疏水性硅烷偶联剂,硅烷偶联剂中的水解基团与微腔表面的羟基发生水解反应,硅烷分子被修饰到微腔表面,光学微腔表面形成疏水性化学键。本发明的光学微腔经测试,在相对湿度为35％和75％的环境中,经过两周时间,品质因子Q值仍能保持10～(8)以上。因此,本发明的光学微腔的品质因子具有良好的环境稳定性,具有广泛的应用前景。(The invention discloses an environment-stable optical microcavity with an ultrahigh quality factor and a preparation method thereof. The environment-stable ultrahigh-quality factor optical microcavity is obtained by depositing a silane coupling agent layer on the surface of a whispering gallery mode optical microcavity by a chemical vapor deposition method, and the surface of the whispering gallery mode optical microcavity is chemically modified to form a stable structure which is not influenced by the environment. The silane coupling agent is a hydrophobic silane coupling agent, a hydrolysis group in the silane coupling agent and hydroxyl on the surface of the microcavity are subjected to hydrolysis reaction, silane molecules are modified to the surface of the microcavity, and the surface of the optical microcavity forms a hydrophobic chemical bond. The optical microcavity of the invention is tested, and the Q value of the quality factor can still keep 10 after two weeks in the environment with the relative humidity of 35% and 75% 8 The above. Therefore, the quality factor of the optical microcavity has good environmental stability and wide application prospect.)

1. The environment-stable ultrahigh-quality-factor optical microcavity is characterized in that a silane coupling agent layer is deposited on the surface of the whispering gallery mode optical microcavity by a chemical vapor deposition method, the surface of the optical microcavity is chemically modified to form a stable structure which is not influenced by the environment, and the silane coupling agent is a hydrophobic silane coupling agent.

2. The environmentally stable ultra-high quality factor optical microcavity of claim 1, wherein the structure of the whispering gallery mode optical microcavity comprises spherical spheres, disc-on-chip micro disks, wedge-on-chip micro cavities, ring-on-chip micro toroids, micro bottles or micro bubble-type micro bubbles.

3. The environmentally stable ultra-high quality factor optical microcavity of claim 1 wherein the whispering gallery mode optical microcavity is formed from an organosiloxane and/or an inorganic silicone compound.

4. The environmentally stable, ultra-high quality factor optical microcavity of claim 1 wherein the silane coupling agent has the general structural formula RSiX₃Wherein, R is a hydrocarbon group, a hydrocarbon group containing double bonds, a polyoxypropylene group, a long-chain perfluoroalkyl group, a polysiloxane group or a hydrocarbon group containing at least one group of an aryl group, an ester group, an ether group and an amide group, and X is a halogen, an alkoxy group or an acyloxy group.

5. The environmentally stable ultra-high quality factor optical microcavity of claim 4, wherein the silane coupling agent is n-octyltrichlorosilane and/or 1H,1H,2H, 2H-perfluorooctyltrichlorosilane; the deposited layer of silane coupling agent is a monolayer.

6. The method of any of claims 1-5 for preparing an environmentally stable ultra-high quality factor optical microcavity, comprising the steps of:

step 1: preparing a whispering gallery mode optical microcavity, cleaning the surface of the whispering gallery mode optical microcavity and removing dangling keys on the surface of the whispering gallery mode optical microcavity;

step 2: and (3) depositing a silicon-oxygen coupling agent on the surface of the whispering gallery mode optical microcavity obtained by the treatment in the step (1) by adopting a chemical vapor deposition method.

7. The method for preparing an environmentally stable ultra-high quality factor optical microcavity of claim 6, wherein the method for preparing the whispering gallery mode optical microcavity in step 1 comprises micro-nano processing or hot melt processing.

8. The method of claim 7, wherein the step of fabricating the whispering gallery mode optical microcavity comprises micro-nano machining using a carbon dioxide laser.

9. The method for preparing an environmentally stable ultra-high quality factor optical microcavity of claim 6, wherein the step 1 of cleaning the surface of the whispering gallery mode optical microcavity and removing the dangling bonds on the surface thereof comprises: oxygen plasma treatment is used.

10. The method of claim 9, wherein the oxygen plasma treatment is performed under the following process conditions: the oxygen pressure is 60-100 mL/min, the power is 100-150W, and the time is 1-5 min.

Technical Field

The invention relates to an environment-stable optical microcavity with an ultrahigh quality factor and a preparation method thereof, and belongs to the technical field of micro-nano optical devices.

Background

As a special optical resonant cavity, the whispering gallery mode optical microcavity constrains the optical field at the annular boundary so that continuous total reflection occurs. When the optical path of a light beam propagating around a geometric structure boundary for one turn satisfies an integral multiple of a wavelength, an optical frequency resonance phenomenon occurs. The ring-shaped microstructure used to confine the light field is called whispering gallery mode optical microcavity. The whispering gallery mode optical microcavity has the characteristics of extremely small microcavity size, ultrahigh quality factor (Q), small mode volume, extremely high internal energy density and the like, and has great potential in the application of next-generation integrated optical devices. Can be used as a high-sensitivity detector, for researching weak light nonlinear optics, for manufacturing a micro laser on a chip with a low threshold value, for manufacturing an amplifier, a filter, a modulator and the like of an optical communication network.

The Q value is an important characteristic parameter quantification of the microcavity. It describes the magnitude of the optical loss of the microcavity and the storage capacity of the energy coupled into the cavity, and also indicates the lifetime of the photon in the microcavity and the spectral line width of the resonance peak. The magnitude of the Q-value is closely related to many applications of the microcavity. It determines the detection limit of the microcavity and determines the intensity of the nonlinear effect within the cavity. The silicon dioxide microcavities have high Q values (10)⁶～10⁹) And the preparation method is compatible with the existing COMS process and is widely concerned. However, since the surface hydroxyl groups of the silicon dioxide microcavities adsorb traces of water and other molecules, the Q value of the devices is unstable during use and gradually decreases by about an order of magnitude over time. Current research in advanced optical technologies based on high Q silica microcavities, such as the generation and application of soliton combs, is generally in N₂The atmosphere is protected and specially packaged. The method not only increases the preparation difficulty of the high-Q microcavity device, but also greatly limits the practical application prospect of the device.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the surface of the existing whispering gallery mode optical microcavity can adsorb moisture and other small molecules, so that the quality factor Q value of the device is unstable in the using process and the like.

In order to solve the technical problems, the invention provides an environment-stable ultrahigh-quality-factor optical microcavity which is obtained by depositing a silane coupling agent layer on the surface of a whispering gallery mode optical microcavity by a chemical vapor deposition method, wherein the surface of the optical microcavity is chemically modified to form a stable structure which is not influenced by the environment, and the silane coupling agent is a hydrophobic silane coupling agent.

Preferably, the optical microcavity structure includes a spherical (spheres), a disc-on-chip (micro disks), a wedge-on-chip (micro wedge), a core-on-chip (micro toroids), a micro bottles (micro bottles), or a micro bubbles (micro bubbles).

Preferably, the material of the whispering gallery mode optical microcavity is organosiloxane and/or inorganic silicone oxide compound.

Preferably, the general structural formula of the silane coupling agent is RSiX₃Wherein, R is a hydrocarbon group, a hydrocarbon group containing double bonds, a polyoxypropylene group, a long-chain perfluoroalkyl group, a polysiloxane group or a hydrocarbon group containing at least one group of an aryl group, an ester group, an ether group and an amide group, and X is a halogen, an alkoxy group or an acyloxy group.

Preferably, the silane coupling agent is n-octyl trichlorosilane and/or 1H,1H,2H, 2H-perfluorooctyl trichlorosilane; the deposited layer of silane coupling agent is a monolayer.

The invention also provides a preparation method of the environment-stable ultrahigh-quality-factor optical microcavity, which comprises the following steps:

step 1: preparing a whispering gallery mode optical microcavity, cleaning the surface of the whispering gallery mode optical microcavity and removing dangling keys on the surface of the whispering gallery mode optical microcavity;

step 2: and (3) depositing a silicon-oxygen coupling agent on the surface of the whispering gallery mode optical microcavity obtained by the treatment in the step (1) by adopting a chemical vapor deposition method.

Preferably, the method for preparing the whispering gallery mode optical microcavity in the step 1 comprises micro-nano processing or hot melting processing.

More preferably, the method for preparing the whispering gallery mode optical microcavity comprises micro-nano processing by a carbon dioxide laser.

Preferably, the step 1 of cleaning the whispering gallery mode optical microcavity surface and removing dangling bonds on the surface is specifically as follows: oxygen plasma treatment is used.

More preferably, the process conditions of the oxygen plasma treatment are: the oxygen pressure is 60-100 mL/min, the power is 100-150W, and the time is 1-5 min.

The technical principle of the invention is as follows:

the silane coupling agent is a low molecular organosilicon compound with a special structure and has a general formula of RSiX₃In the formula, R represents amino, sulfydryl, vinyl, epoxy, cyano, methyl-propyl-vinyl-acyloxy and other groups, and the groups and different matrix resins have stronger reaction capability. X represents a group capable of hydrolysis, such as halogen, alkoxy, acyloxy, etc. In the embodiment of the invention, silane molecules containing three halogen groups are selected, so that condensation reaction does not occur, a multi-layer film structure is not formed in vapor deposition, and a surface fine defect structure is not formed. In addition, the R group is further screened, and hydrophobic groups are selected, including but not limited to: a hydrocarbon group, a hydrocarbon group containing an aryl group, an ester group, an ether group, an amide group, etc.; a hydrocarbon group having a double bond; polyoxypropylene groups, long chain perfluoroalkyl groups, polysiloxane groups, and the like. In the preparation process, the oxygen plasma is used for treating the micro-cavity, so that the surface can be cleaned, dangling bonds on the surface of silicon dioxide can be removed, the density of surface hydroxyl groups is increased, and the formation of a compact and uniform monomolecular layer is promoted.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, a silane coupling agent layer is deposited on the surface of the whispering gallery mode optical microcavity by a chemical vapor deposition method to carry out chemical modification on the surface of the optical microcavity, wherein, for the selection of the silane coupling agent, a hydrophobic silane coupling agent is adopted, a hydrolysis group in the silane coupling agent and a hydroxyl group on the surface of the microcavity are subjected to hydrolysis reaction, and silane molecules are modified to the surface of the microcavity, so that a hydrophobic silicon-containing chemical bond is formed on the surface of the optical microcavity, and the problems that the surface of the existing whispering gallery mode optical microcavity can adsorb moisture and other small molecules, so that the quality factor Q value of a device is unstable in the using process and the like are solved;

2. the optical microcavity of the invention is tested, and the Q value of the quality factor can still keep 10 after two weeks in the environment with the relative humidity of 35% and 75%⁸Therefore, the quality factor of the optical microcavity has good environmental stability and wide application prospect.

3. The preparation process is simple, the manpower and equipment investment cost is low, and the large-scale production can be realized.

Drawings

FIG. 1 is a transmission spectrum measurement light path diagram;

FIG. 2 is a plot of Q-value variation over days for the modified microcavities of examples 1 and 2 and the blank microcavity of comparative example 1 versus the resonant peak width in the transmission spectrum for the first and thirteenth days at an ambient relative humidity of 35%; wherein (a), (b) represent plots of Q and formant as a function of days for the empty microsphere cavities (Bare silica) of comparative example 1; (c) and (d) represents the Q value and the resonance peak chart of the microsphere cavity (C-silica) modified by n-octyl trichlorosilane along with the change of days; (e) and (F) represents the Q value and the resonance peak chart of the microsphere cavity (F-silica) modified by 1H,1H,2H, 2H-perfluorooctyl trichlorosilane along with the change of days.

FIG. 3 is a plot of the Q-value versus number of days for the modified microcavities of examples 1 and 2 and the blank microcavities of comparative example 1 versus the resonant peak width in the transmission spectrum for the first and thirteenth days at an ambient relative humidity of 75%; wherein (a), (b) represent plots of Q and resonance peaks of the blank microsphere cavity of comparative example 1 as a function of days; (c) and (d) represents Q value and resonance peak chart of microsphere cavity (C-silica) modified by n-octyl trichlorosilane along with days; (e) and (F) represents the Q value and the resonance peak chart of the microsphere cavity (F-silica) modified by 1H,1H,2H, 2H-perfluorooctyl trichlorosilane along with the change of days.

Detailed Description

In order to make the invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.

Example 1

A preparation method of an environment-stable ultrahigh-quality-factor optical microcavity comprises the following specific experimental steps:

(1) firing a silica microsphere cavity with the diameter of about 120 mu m by using a carbon dioxide laser (the wavelength of a laser light source is 1550nm, and lasers with other wave bands can also be adopted);

(2) oxygen plasma treatment was used: transferring the glass slide carrying at least one microsphere obtained in the step (1) into an oxygen plasma cavity. The oxygen pressure was set to 80mL/min and the power was set to 120W. The sample was exposed to an oxygen plasma for 2 minutes. The slide is removed from the plasma chamber.

(3) And (3) putting the glass slide loaded with at least one microsphere obtained in the step (2) into a vacuum dryer in a fume hood. The vacuum drier was evacuated and then purged with high purity nitrogen several times to remove moisture from the drier. Also in the fume hood, the reagent bottle containing n-octyltrichlorosilane was opened, and then the opened reagent bottle was placed in a desiccator. The lid of the vacuum dryer was closed and the outlet was then connected to the vacuum double row tube. The vacuum pump is turned on and a timing reaction is initiated once a vacuum seal is formed between the lid and base. This will cause the silane coupling agent to be deposited on the surface in the form of a thin film. After 8 minutes, the vacuum was closed, then the port was slowly opened, nitrogen was admitted to the dryer, and chemical deposition for 8 minutes was sufficient to form a uniform monolayer of silane coupling agent on the surface of the microsphere cavity, thereby yielding an environmentally stable ultrahigh-quality factor optical microcavity.

Example 2

A preparation method of an environment-stable ultrahigh-quality-factor optical microcavity comprises the following specific experimental steps:

(1) firing a silica microsphere cavity with the diameter of about 120 mu m by using a carbon dioxide laser (the wavelength of a laser light source is 1550nm, and lasers with other wave bands can also be adopted);

(2) oxygen plasma treatment was used: transferring the glass slide carrying at least one microsphere obtained in the step (1) into an oxygen plasma cavity. The oxygen pressure was set to 80mL/min and the power was set to 120W. The sample was exposed to an oxygen plasma for 2 minutes. The slide is removed from the plasma chamber.

(3) And (3) putting the glass slide loaded with at least one microsphere obtained in the step (2) into a vacuum dryer in a fume hood. The vacuum drier was evacuated and then purged with high purity nitrogen several times to remove moisture from the drier. Also in the fume hood, the reagent bottle containing 1H, 2H-perfluorooctyltrichlorosilane was opened, and then the opened reagent bottle was placed in a desiccator. The lid of the vacuum dryer was closed and the outlet was then connected to the vacuum double row tube. The vacuum pump is turned on and a timing reaction is initiated once a vacuum seal is formed between the lid and base. This will cause the silane coupling agent to be deposited on the surface in the form of a thin film. After 8 minutes, the vacuum was closed, then the port was slowly opened, nitrogen was admitted to the dryer, and chemical deposition for 8 minutes was sufficient to form a uniform monolayer of silane coupling agent on the surface of the microsphere cavity, thereby yielding an environmentally stable ultrahigh-quality factor optical microcavity.

Comparative example 1

Preparation of an unmodified blank microcavity:

firing a silica hollow microsphere cavity with the diameter of about 120 mu m by using a carbon dioxide laser (the wavelength of a laser light source is 1550nm, and lasers with other wave bands can also be adopted);

test:

the modified microcavities of examples 1 and 2 and the blank microcavity of comparative example 1 were pumped by a semiconductor laser, respectively, and an optical signal was converted into an electrical signal by a photodetector, and a transmission signal was obtained on an oscilloscope, and a transmission spectrum measurement optical path diagram is shown in fig. 1. And obtaining the Q value of the microcavity by Lorentz fitting of the obtained resonance peak signal. The resonance peaks under different degrees of coupling are measured, the intrinsic quality factor of the microcavity under zero coupling can be determined by linearly fitting the Q value and the coupling degree to obtain the y-intercept, and the measurement is continuously carried out within two weeks. Meanwhile, two different environmental humidities are obtained by setting the parameters of the humidistat, one group of the blank micro-cavity and the modified micro-cavity is placed in an environment with the relative humidity of 35%, the other group is placed in an environment with the relative humidity of 75%, and the test results are respectively shown in fig. 2 and fig. 3. From the transmission spectrum results of fig. 2 and 3, it can be seen that the quality factors of the modified microcavities of examples 1 and 2 were almost unchanged (maintained at 10) in two weeks, regardless of whether the ambient relative humidity was 35% or 75%⁸Above). While the blank microcavity of comparative example 1 consisted of the original 10 in two weeks⁸Down to a magnitude of 10⁷The resonance peak becomes significantly broader. Thus, the modified microcavities prepared in examples 1 and 2 have good environmental stability in terms of quality factor.

The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way and substantially, it should be noted that those skilled in the art may make several modifications and additions without departing from the scope of the present invention, which should also be construed as a protection scope of the present invention.