CN113252085B - Opto-mechanical microcavity structure containing nonlinear mechanical oscillator, measurement system and measurement method - Google Patents
Opto-mechanical microcavity structure containing nonlinear mechanical oscillator, measurement system and measurement method Download PDFInfo
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- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/268—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light using optical fibres
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- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
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- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
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Abstract
The invention discloses an opto-mechanical microcavity structure containing a nonlinear mechanical vibrator, a measurement system and a measurement method, and belongs to the field of micro-nano optoelectronic microcavity sensing. In an opto-mechanical microcavity formed by two one-dimensional photonic crystal micro-nano beams, a movable micro-nano beam is designed in a structure containing a nonlinear mechanical oscillator, and the micro-disc microcavity is used for monitoring the movement of a micro probe to realize the measurement of the displacement of the nonlinear mechanical oscillator so as to realize the experimental study of the nonlinear optical-mechanical coupling characteristic driven by the cavity optical force integrated on an all-optical chip; meanwhile, a method based on two paths of micro-nano optical fibers-optical microcavity coupling is designed for simultaneously realizing optical-mechanical coupling pumping and displacement detection, and the all-optical detection system can effectively observe the nonlinear phenomenon in the opto-mechanical microcavity system. The design that a nonlinear mechanical oscillator is introduced into an opto-mechanical microcavity is proposed for the first time, and the observation of the nonlinear phenomenon under the action of opto-mechanical coupling is realized through experimental measurement.
Description
Technical Field
The invention relates to the technical field of micro-nano photoelectron microcavity sensing, in particular to an opto-mechanical microcavity structure containing a nonlinear mechanical vibrator, a measurement system and a measurement method.
Background
The photomechanical microcavity is a micro-nano system designed based on photon-phonon interaction of mutual coupling of optical microcavity energy and mechanical microcavity energy, and is used for researching abundant optical/mechanical resonance characteristics and optical-mechanical coupling characteristics in the photomechanical microcavity. The optical microcavity structure can bind light field energy in the structure with the micro-nano size so as to realize high optical resonance Q value, and the microcavity structure can displace itself by optical gradient force generated when the gathered light field energy is applied to a semiconductor silicon material.
When the microcavity structure is applied to a mechanical vibrator supported by a cantilever beam, namely the optical microcavity itself is also used as a mechanical vibrator, the opto-mechanical microcavity structure consisting of the micro-nano mechanical vibrator can generate mechanical resonance or even stimulated oscillation under the excitation of pump laser energy. Typically, the microcavity structure on the chip mainly includes a Fabry-Perot (FP) cavity, a Whispering Gallery (WGM) microcavity and a photonic crystal (PhC) microcavity. Compared with other two microcavities, the photonic crystal microcavity has the advantages of extremely small mode volume, high optical Q value and the like, so that the photonic crystal microcavity is more suitable for being designed in an opto-mechanical system. In addition, due to the ultralow mass and the easily-integrated cantilever support structure, the one-dimensional photonic crystal micro-nano beam microcavity can be designed into various on-chip integrated opto-mechanical microcavity systems and can be widely applied to the fields of optical communication, sensing and the like. When the microcavity of the one-dimensional photonic crystal is applied to an opto-mechanical system, external physical quantities (such as displacement, stress, acceleration and the like) are applied to a mechanical oscillator supported by a cantilever beam to enable the mechanical oscillator to generate dielectric boundary movement or cavity deformation, so that the opto-mechanical coupling strength in the system changes, and the change of external physical parameters is represented by the optical resonance characteristic and the mechanical resonance characteristic of the opto-mechanical microcavity.
The optical-mechanical interaction effects of the optical and mechanical microcavities in the opto-mechanical microcavity can be numerically solved and theoretically analyzed using the Langevin coupling equation. Generally, in order to simplify the solution of the opto-mechanical coupling equation, most opto-mechanical systems process the displacement generated by the mechanical vibrator linearly. In fact, however, the nonlinear phenomenon itself exists in opto-mechanical systems, and when cavity optical forces are excited in strong light-mechanical coupling, the displacement of the high order terms generated by the mechanical oscillator is not equivalently negligible, and conversely, the nonlinear characteristic generates a distinct and abundant opto-mechanical interaction phenomenon in opto-mechanical microcavity systems. At present, the theoretical research of nonlinear optical mechanical microcavities mainly focuses on weak light-mechanical coupling, and considers nonlinear phenomena generated by high-order term displacement (square, cubic term of mechanical vibrator, etc.) of a mechanical cavity under the driving of cavity light force, such as optical mechanical induced transparency, optical mechanical chaos, etc. However, under the weak opto-mechanical coupling effect, the nonlinear phenomenon caused by the displacement of the high-order term in such opto-mechanical microcavity is difficult to be experimentally demonstrated, so that another opto-mechanical microcavity based on the nonlinear mechanical oscillator can theoretically and experimentally demonstrate the nonlinear phenomenon in the opto-mechanical system. Theoretically, the mechanical vibrator structure in the optical-mechanical microcavity structure is designed to be nonlinear, and when the nonlinear mechanical vibrator and the optical microcavity are subjected to optical-mechanical coupling, cavity optical force drives the mechanical vibrator to move so as to generate abundant nonlinear phenomena. The theoretical models are used for carrying out numerical solution and analysis on the opto-mechanical microcavity based on the nonlinear mechanical oscillator, and theoretically analyzing the nonlinear phenomenon (such as opto-mechanical induced transparency, parameter opto-mechanical vibration, different mechanical oscillator frequency synthesis and the like) of the opto-mechanical microcavity, which is caused by the nonlinear mechanical oscillator when the nonlinear mechanical oscillator is driven by a strong cavity optical force and has a large displacement, but the theoretical model is not demonstrated in an experimental system at present.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides an opto-mechanical microcavity structure containing a nonlinear mechanical oscillator, a measurement system and a measurement method.A movable micro-nano beam is designed in an opto-mechanical microcavity formed by two one-dimensional photonic crystal micro-nano beams, and the micro-disc microcavity is used for monitoring the movement of a micro probe to realize the measurement of the displacement of the nonlinear mechanical oscillator so as to realize the experimental study of the nonlinear optical-mechanical coupling characteristic driven by the cavity optical force integrated on a full optical sheet; meanwhile, a method based on two paths of micro-nano optical fibers-optical microcavity coupling is designed for simultaneously realizing optical-mechanical coupling pumping and displacement detection, and the all-optical detection system can effectively observe the nonlinear phenomenon in the opto-mechanical microcavity system.
In order to achieve the purpose, the invention provides an opto-mechanical microcavity structure containing a nonlinear mechanical vibrator, which comprises a silicon base, a first micro-nano beam, a second micro-nano beam, a linear mechanical vibrator, a nonlinear mechanical vibrator and a measuring micro-disc, wherein the first micro-nano beam, the second micro-nano beam, the linear mechanical vibrator and the nonlinear mechanical vibrator are positioned on the same plane;
the two ends of the first micro-nano beam and the two ends of the linear mechanical vibrator are both connected with the silicon base, the second micro-nano beam is fixedly connected to one side of the linear mechanical vibrator, an air gap is formed between the second micro-nano beam and the first micro-nano beam, and a second air groove is formed between the second micro-nano beam and the linear mechanical vibrator;
the nonlinear mechanical vibrator comprises at least two curve arms which are connected in series at the other side of the linear mechanical vibrator, a mass block is arranged in the middle of each curve arm, a micro-nano probe is arranged on each mass block, the measuring micro disc is arranged at a position adjacent to the micro-nano probe, and a first air groove is formed between the measuring micro disc and the micro-nano probe;
the curve line type of the curve arm is as follows:
in the formula (I), the compound is shown in the specification,hthe pre-bent height of the curved arm is shown,lrepresents the length of the curvilinear arm;
the bottoms of the first micro-nano beam, the second micro-nano beam, the linear mechanical vibrator and the nonlinear mechanical vibrator are all suspended.
In one embodiment, the optical structures and the geometric dimensions of the first micro-nano beam and the second micro-nano beam are the same;
a plurality of air through holes are formed in the first micro-nano beam at intervals along the length direction, and the aperture of the air through hole in the defect area of the first micro-nano beam is gradually reduced along the direction from the middle to the two ends;
the aperture of the air through hole in the reflection area of the first micro-nano beam is equal to the minimum aperture of the air through hole in the defect area of the first micro-nano beam.
In one embodiment, the radius of the air through hole of the defect area on the first micro-nano beam is from the central hole r0Holes r gradually changing to two ends in the length of =127.9nm7=105.3nm；
The radius of the air through holes of the two reflecting regions on the first micro-nano beam is 105.3nm, and the distance between any two adjacent air through holes on the first micro-nano beam is equal to the lattice constant of 364.8 nm;
the initial width of the air gap between the second micro-nano beam and the first micro-nano beam is 125 nm.
In order to achieve the above object, the present invention further provides a system for testing an opto-mechanical microcavity structure including a nonlinear mechanical oscillator, including:
a first signal output component for outputting a first signal light;
the first micro-nano tapered optical fiber is connected with the first signal output assembly, is in contact connection with a first micro-nano beam in the opto-mechanical microcavity structure, and is used for coupling the first signal light into the opto-mechanical microcavity structure to serve as pumping signal light;
a second signal output component for outputting a second signal light;
the second micro-nano tapered optical fiber is connected with the second signal output assembly, is in contact connection with a measuring micro-disc in the opto-mechanical microcavity structure, and is used for coupling the second signal light into the opto-mechanical microcavity structure to serve as detection signal light;
the photoelectric detector is connected with the first micro-nano tapered optical fiber and the second micro-nano tapered optical fiber and used for performing photoelectric conversion so as to convert the pumping signal light into a first voltage signal and convert the detection signal light into a second voltage signal;
the display unit is used for displaying the test result;
the high-speed data acquisition card is connected with the photoelectric detector, the first signal output component, the second signal output component and the display unit and is used for synchronizing a first voltage signal with the first signal output component and the second signal output component and then displaying an optical resonance mode of the opto-mechanical microcavity structure by the display unit;
and the real-time signal analyzer is connected with the photoelectric detector and the display unit and is used for obtaining the mechanical resonance characteristic of the mechanical oscillator of the opto-mechanical microcavity structure according to the second voltage signal and displaying the mechanical resonance characteristic through the display unit.
In one embodiment, the device further comprises a vacuum device detection unit, wherein the vacuum device detection unit comprises a vacuum box, and a first micro-nano displacement platform, a second micro-nano displacement platform and a third micro-nano displacement platform which are arranged in the vacuum box;
the first micro-nano tapered fiber is fixed on the first micro-nano displacement platform through a first fiber fixing clamp, the second micro-nano tapered fiber is fixed on the second micro-nano displacement platform through a second fiber fixing clamp, and the opto-mechanical microcavity structure is fixed on the third micro-nano displacement platform through a chip fixing platform to be detected.
In one embodiment, the first micro-nano tapered fiber and the second micro-nano tapered fiber are U-shaped micro-nano tapered fibers with micro-pits, and the central core diameter of the U-shaped micro-nano tapered fibers is less than 1.5 μm from standard single-mode optical fiber hot melting tapering.
In one embodiment, the first signal output component comprises a first tunable narrow linewidth laser, a first optical fiber polarization controller and a first single-mode optical fiber attenuator which are connected in sequence through an optical fiber;
the second signal output assembly comprises a second tunable narrow-linewidth laser, a second optical fiber polarization controller and a second single-mode optical fiber attenuator which are sequentially connected through optical fibers;
the first tunable narrow-linewidth laser and the second tunable narrow-linewidth laser work in a C wave band, the output light wavelength is 1500.00-1620.00 nm, the light source output power of the first tunable narrow-linewidth laser is 150 muW to ensure that strong enough cavity optical force is generated to drive a mechanical oscillator, and the light source output power of the second tunable narrow-linewidth laser is 30 muW to avoid a nonlinear effect caused by a thermo-optical effect.
In order to achieve the above object, the present invention further provides a testing method of the testing system, including the following steps:
step 1, assembling and opening each part of a test system, and finishing physical coupling operation between a first micro-nano tapered fiber and a first micro-nano beam and between a second micro-nano tapered fiber and a measurement micro disc in an air environment; then the vacuum box is pumped until the pressure in the vacuum box reaches 6.5
；
step 3, arranging the first tunable narrow linewidth laser at the half-wave position of the optical resonance peak to test the mechanical resonance mode in the opto-mechanical microcavity;
step 4, scanning the measured micro-disc by using a second tunable narrow linewidth laser within the wavelength range of 1500nm-1620nm to obtain the wavelength shift of an optical resonance peak of the measured micro-disc so as to monitor the displacement of the micro-nano probe arranged on the nonlinear mechanical vibrator;
and 5, carrying out intensity modulation on the cavity optical force for driving the nonlinear mechanical vibrator to move so as to measure the nonlinear characteristic of the nonlinear mechanical vibrator.
In one embodiment, in step 1, the completing of the physical coupling operation between the first micro-nano tapered fiber and the first micro-nano beam, and between the second micro-nano tapered fiber and the measurement micro-disc specifically includes:
fixing the first micro-nano tapered optical fiber and the second micro-nano tapered optical fiber on a first optical fiber fixing clamp and a second optical fiber fixing clamp respectively through UV glue;
polishing a cylindrical 2B pen core with the diameter of 0.5cm into a wedge-shaped needle-shaped head with the width of 8 mu m, pressing and pressing the wedge-shaped needle-shaped head at the middle positions of a first micro-nano tapered optical fiber and a second micro-nano tapered optical fiber with the assistance of a mechanical displacement table, burning the pressing point by using a micro alcohol lamp flame for 1-2 seconds, withdrawing, and finally separating the first micro-nano tapered optical fiber and the second micro-nano tapered optical fiber from the wedge-shaped needle-shaped head;
and finishing physical coupling operation between the first micro-nano tapered fiber and the first micro-nano beam and between the second micro-nano tapered fiber and the measuring micro disc with the assistance of a high-power optical microscope and a high-resolution CCD camera.
In one embodiment, step 5 specifically includes:
inputting a square wave excitation signal with the level amplitude of 5Vpp and the frequency set to be near 10.22MHz for scanning by a signal generator through an external voltage driving port of a first tunable narrow-linewidth laser;
after the intensity of the square wave excitation signal is modulated, the cavity optical force applied to the nonlinear mechanical vibrator is also modulated by the square wave excitation signal;
and detecting the resonance peak wavelength of the measurement microdisk by using detection signal light output by the second tunable narrow-linewidth laser.
Compared with the prior art, the opto-mechanical microcavity structure containing the nonlinear mechanical vibrator, the measurement system and the measurement method provided by the invention have the following beneficial technical effects:
1. a nonlinear mechanical vibrator is designed in an on-chip integrated optical-mechanical microcavity system for the first time, and a nonlinear phenomenon in an optical-mechanical coupling process is observed in an all-optical pumping-detection mode from an experimental angle;
2. the method of coupling two micro-nano optical fibers and an optical resonant cavity is adopted, one path is used as pumping light to excite cavity optical force in a mechanical system, the other path is used as detection signal light to measure displacement of a nonlinear mechanical oscillator, and the two micro-nano optical fiber coupling modes realize a complete all-optical detection system and are superior to an electrical measurement mode in a traditional on-chip integrated optical-mechanical-electrical microcavity system;
3. the opto-mechanical microcavity structure provided by the invention has optimized optical and mechanical structures and better experimental realizability, and the designed opto-mechanical microcavity structure parameters are easy for semiconductor processing and manufacturing and have good applicability.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic diagram of an opto-mechanical microcavity structure including a nonlinear mechanical resonator according to an embodiment of the present invention;
FIG. 2 is an enlarged schematic view of a first air tank in an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of an opto-mechanical microcavity in accordance with an embodiment of the present invention;
FIG. 4 is a schematic diagram of the dimensions of a curved arm in an embodiment of the present invention;
FIG. 5 is a block diagram of a test system according to an embodiment of the present invention;
FIG. 6 is a schematic diagram illustrating a connection relationship between an opto-mechanical microcavity structure including a nonlinear mechanical oscillator and a first micro-nano tapered fiber and a second micro-nano tapered fiber in a test system according to an embodiment of the present invention;
FIG. 7 is a schematic structural diagram of a vacuum device detection unit according to an embodiment of the present invention;
FIG. 8 is a flow chart illustrating a testing method according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of a method for manufacturing a U-shaped micro-nano tapered optical fiber with a dimple according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of an optical resonance mode test spectrum of a coupled one-dimensional photonic crystal micro-nano beam microcavity in an embodiment of the present invention;
FIG. 11 is a schematic mechanical spectrum of a mechanical oscillator in an opto-mechanical microcavity measured at a blue detuned position in an embodiment of the present invention;
FIG. 12 is a schematic static spectrum of a microdisc microcavity for nonlinear mechanical oscillator displacement measurement in an embodiment of the present invention;
FIG. 13 is a schematic diagram illustrating displacement of the second-stage nonlinear mechanical oscillator measured under different pump signal lights according to an embodiment of the present invention;
fig. 14 is a schematic diagram of the resonance frequency division phenomenon of the mechanical vibrator under the strong light-mechanical coupling effect in the embodiment of the present invention.
Reference numerals: the structure comprises a silicon base 1, a first micro-nano beam 10, an air through hole 101, a defect region 102, a reflection region 103, a second micro-nano beam 11, a linear mechanical vibrator 12, a first connecting beam 121, a second connecting beam 122, a second air groove 123, a third connecting beam 124, a hollow groove 125, a nonlinear mechanical vibrator 13, a micro-nano probe 131, a first air groove 132, a curved arm 133, a mass block 134, a measuring micro disc 14, a fan-shaped groove 141, a plane cavity 15 and an air gap 16;
the device comprises a first tunable narrow-linewidth laser 211, a first optical fiber polarization controller 212, a first single-mode optical fiber attenuator 213, a first micro-nano tapered optical fiber 22, a second tunable narrow-linewidth laser 231, a second optical fiber polarization controller 232, a second single-mode optical fiber attenuator 233, a second micro-nano tapered optical fiber 24, a vacuum device detection unit 25, a vacuum box 251, a first micro-nano displacement platform 252, a second micro-nano displacement platform 253, a third micro-nano displacement platform 254, a first optical fiber fixing clamp 255, a second optical fiber fixing clamp 256, a chip fixing platform 257 to be detected, a chip 258 to be detected, a photoelectric detector 26, a display unit 27, a high-speed data acquisition card 28, a real-time signal analyzer 29, a high-power optical microscope 30, a high-resolution CCD camera 31 and a signal generator 32;
a wedge-shaped needle head 41, an alcohol lamp 42 and UV glue 43.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; the connection can be mechanical connection, electrical connection, physical connection or wireless communication connection; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
As shown in fig. 1 to 4, the opto-mechanical microcavity structure including a nonlinear mechanical oscillator 13 disclosed in this embodiment includes a silicon substrate 1, and a first micro-nano beam 10, a second micro-nano beam 11, a linear mechanical oscillator 12, a nonlinear mechanical oscillator 13, and a measurement microdisk 14 located on the same plane, where bottoms of the first micro-nano beam 10, the second micro-nano beam 11, the linear mechanical oscillator 12, and the nonlinear mechanical oscillator 13 are all suspended. Specifically, the silicon substrate 1 is a silicon dioxide layer (BOX layer), the silicon substrate 1 is subjected to corrosion treatment by using a corrosion solution, so that a closed planar cavity 15 is formed on the silicon substrate 1, and the first micro-nano beam 10, the second micro-nano beam 11, the linear mechanical vibrator 12, the nonlinear mechanical vibrator 13 and the measurement microdisk 14 are all located in the planar cavity 15.
Referring to fig. 2, in this embodiment, the first micro-nano beam 10 and the second micro-nano beam 11 are both of a one-dimensional photonic crystal micro-nano beam structure, and the first micro-nano beam 10 and the second micro-nano beam 11 are arranged side by side with an air gap 16 therebetween, thereby forming an opto-mechanical microcavity capable of generating cavity optical force. Specifically, the optical structures and the geometric dimensions of the first micro-nano beam 10 and the second micro-nano beam 11 are the same. Taking the first micro-nano beam 10 as an example, after simulation optimization, the width of the first micro-nano beam 10 is 556nm, and the thickness of the first micro-nano beam 10 is 220nm, and in order to generate a one-dimensional photonic crystal microcavity on the first micro-nano beam 10, a plurality of air through holes 101 are arranged in the middle of the first micro-nano beam 10 along the length direction. Referring to fig. 2, the first micro-nano beam 10 includes a defect region 102 located in the middle of the first micro-nano beam 10 and reflective regions 103 located at both ends. The radius of the air through hole 101 of the defect region 102 is from the central hole r0Holes r gradually changing to two ends in the length of =127.9nm7=105.3nm, the radius of the air via 101 of both reflective regions 103 is 105.3 nm. The distance between any two adjacent air vias 101 is equal to the lattice constant 364.8 nm. The initial width of the air gap 16 between the first micro-nano beam 10 and the second micro-nano beam 11 is 125nm, and the width of the air gap 16 is modulated along with the detuning frequency modulation of the laser under the driving of the cavity optical force in the optical mechanical microcavity.
In the specific implementation process, two ends of the first micro-nano beam 10 are fixedly connected with the silicon base 1, the first micro-nano beam serves as a fixed micro-nano beam of the opto-mechanical microcavity, and the bottom of the first micro-nano beam 10 is suspended. Two ends of the linear mechanical vibrator 12 are fixedly connected with the silicon base 1, the second micro-nano beam 11 is fixedly connected to one side of the linear mechanical vibrator 12, an air gap 16 is formed between the second micro-nano beam 11 and the first micro-nano beam 10, and the second micro-nano beam 11 serves as a movable micro-nano beam of the opto-mechanical microcavity.
Specifically, two ends of the linear mechanical vibrator 12 are connected with the silicon base 1 through a plurality of symmetrical first connecting beams 121, so that the linear mechanical vibrator 12, and the nonlinear mechanical vibrator 13 and the second micro-nano beam 11 connected to the linear mechanical vibrator 12 are all suspended at the bottom. Wherein, the number of the first connection beams 121 is eight, the width thereof is 120nm, and the length thereof is 1.2 μm, that is, each section of the linear mechanical vibrator 12 is connected to the silicon base 1 through four first connection beams 121. Further specifically, two ends of the second micro-nano beam 11 are connected with the linear mechanical oscillator 12 through a second connection beam 122, a second air groove 123 is arranged between the second micro-nano beam 11 and the linear mechanical oscillator 12, the width of the second air groove 123 is 1.5 μm, and the second air groove 123 is a large air groove, so that the interference of the linear mechanical oscillator 12 on the optical field distribution of the one-dimensional photonic crystal microcavity on the second micro-nano beam 11 can be avoided through the second air groove 123.
It should be noted that, in order to facilitate the etching suspension process on the silicon base 1, the plurality of square hollow-out grooves 125 are uniformly opened on the surface of the linear mechanical oscillator 12, so that the entire device can realize a suspension structure after the silicon dioxide layer is etched away after the etching solution fully reacts with the silicon base 1 through the hollow-out grooves 125. In addition, two third connecting beams 124 which are symmetrical to each other are arranged in the second air groove 123, one end of each third connecting beam 124 is connected with the second micro-nano beam 11, and the other end of each third connecting beam is connected with the linear mechanical vibrator 12; the pair of third connecting beams 124 are designed in the second air groove 123, so that cavity optical force can be effectively transmitted, the cavity optical force is applied to the second micro-nano beam 11, the whole linear mechanical vibrator 12 is forced to vibrate, meanwhile, in order to ensure that the third connecting beam 124 structure does not influence the optical resonance mode distribution of the photonic crystal microcavity, after simulation design, the width of a part of beam bodies connected with the second micro-nano beam 11 on the third connecting beam 124 is 70nm, and the distance from the central position of the photonic crystal microcavity is 5.8 μm.
In this embodiment, the nonlinear mechanical vibrator 13 is connected in series to one side of the linear mechanical vibrator 12, that is, the movable second micro-nano beam 11 is designed in the nonlinear mechanical vibrator 13. The nonlinear vibrator is provided with a micro-nano probe 131, the measuring micro disc 14 is arranged at a position adjacent to the micro-nano probe 131, and a first air groove 132 is formed between the measuring micro disc 14 and the micro-nano probe 131. The nonlinear mechanical vibrator 13 displaces along with the linear mechanical vibrator 12 under the action of cavity light to drive the micro-nano probe 131 to displace, and the measurement micro-disc 14 monitors the micro-displacement of the micro-nano probe 131 by using a light field disturbance principle, namely, the displacement of the nonlinear mechanical vibrator 13 is measured, so that experimental research on the nonlinear optical-mechanical coupling characteristic of cavity light force driving integrated on a full-optical chip is realized.
Referring to fig. 4, in a specific implementation process, the nonlinear mechanical oscillator 13 includes at least two curved arms 133, the nonlinear mechanical oscillator 13 in this embodiment is composed of two curved arms 133, and both ends of the curved arms 133 are symmetrically connected to the linear mechanical oscillator 12. The two curved arms 133 are connected into a whole through a mass block 134 positioned in the middle of the curved arms 133, and the micro-nano probe 131 is arranged on the mass block 134. In this embodiment, the curved arms 133 are designed based on the buckling characteristics of the bending beam. Specifically, referring to fig. 3, the curve line of the curve arm 133 is:
in the formula (I), the compound is shown in the specification,hrepresenting the pre-bent height of the curvilinear arm 133,lrepresents the length of the curved arm 133;
when a normalized load F is applied to the middle of the curved arm 133, the corresponding deformation of the curved arm 133 is expressed as:
in the formula, T is a normalized deformation amount, i.e., the displacement amount of the middle point of the curve arm 133 is normalized to the pre-bending height of the curve arm 133; p =h/wIs a geometric factor, is used to characterize the instability of the nonlinear curve arm 133,wis the width of the curved arm 133. When the geometric factor P>At 2.31, the structure is unstable. To ensure the instability of the nonlinear structure, the geometric factor in the present embodiment is set toP =4.16, so the corresponding curved arm 133 has a width of 120nm, a height of 500nm and a length of 16 μm for the entire curved arm 133. A micro-nano probe 131 is designed on the mass block 134 at the middle position of the nonlinear mechanical vibrator 13 and is used for representing the displacement generated in a plane after the nonlinear mechanical vibrator 13 is driven by cavity optical force.
In order to actually measure the displacement of the nonlinear mechanical vibrator 13 driven by the cavity optical force, the present embodiment uses a suspended micro-disk 14 micro-cavity, i.e. a micro-disk echo wall type (WGM) micro-cavity, to measure the displacement of the micro-nano probe 131. The radius of the suspended measurement microdisk 14 is 10 μm, and the original gap of the first air groove 132 between the micro-nano probe 131 and the measurement microdisk is 180 nm. The measuring micro-disk 14 is provided with a plurality of fan-shaped grooves 141 at intervals along the circumferential direction, which is used for facilitating the passage of corrosive liquid and accelerating the full reaction with the silicon substrate 1, so that the outer contour part of the measuring micro-disk 14 (the part is a circular ring from the fan-shaped grooves 141 to the end part of the disk, and the ring width is 2 μm) is a suspended structure.
It should be noted that the opto-mechanical microcavity structure in this embodiment is fabricated on a "silicon-silicon dioxide-silicon" (SOI) wafer by using an E-beam lithography technique and an inductively coupled plasma etching (ICP) technique, the thickness of the silicon layer for fabricating the opto-mechanical microcavity is 220nm, the upper and lower sides of the one-dimensional photonic crystal microcavity and the two-stage mechanical oscillator included in the suspended structure are both air, and the lower air layer is obtained by etching a 3 μm thick silicon dioxide layer with diluted hydrofluoric acid (BOE of 6: 1).
In order to realize experimental test demonstration of the opto-mechanical microcavity structure containing the nonlinear mechanical vibrator 13, the embodiment also discloses a test system based on two micro-nano fiber-microcavity coupling modes. Referring to fig. 5, the test system includes a first signal output component, a first micro-nano tapered fiber 22, a second signal output component, a second micro-nano tapered fiber 24, a photodetector 26, a display unit 27, a high-speed data acquisition card 28, and a real-time signal analyzer 29.
The first signal output component comprises a first tunable narrow-linewidth laser 211, a first optical fiber polarization controller 212 and a first single-mode optical fiber attenuator 213 which are sequentially connected through an optical fiber and used for outputting first signal light; the second signal output component includes a second tunable narrow-linewidth laser 231, a second optical fiber polarization controller 232, and a second single-mode optical fiber attenuator 233, which are connected in sequence through an optical fiber, and is configured to output second signal light. The first tunable narrow-linewidth laser 211 and the second tunable narrow-linewidth laser 231 both work in a C-band, and output light wavelengths are 1500.00-1620.00 nm, wherein the light source output power of the first tunable narrow-linewidth laser 211 is 150 μ W to ensure that a strong enough cavity optical force is generated to drive a mechanical oscillator, and the light source output power of the second tunable narrow-linewidth laser 231 is 30 μ W to avoid a nonlinear effect caused by a thermo-optical effect.
The first micro-nano tapered fiber 22 and the second micro-nano tapered fiber 24 are both micro-concave micro-nano tapered fibers and are manufactured by hot-melting and tapering standard single-mode fibers to micro-nano tapered fibers with the central core diameter lower than 1.5 mu m. One end of the first micro-nano tapered fiber 22 is connected to the first single-mode fiber attenuator 213, and the U-shaped bottom end of the first micro-nano tapered fiber is in contact coupling with the first micro-nano beam 10 in the opto-mechanical microcavity structure, so as to couple the first signal light into the opto-mechanical microcavity structure as pumping signal light. Because the first micro-nano beam 10 is a fixed micro-nano beam of the opto-mechanical microcavity, when the opto-mechanical microcavity cavity is excited by optical force and acts on the movable second micro-nano beam 11, the micro-nano fiber-microcavity coupling mode can avoid influencing the mechanical mode of the movable mechanical vibrator. One end of the second micro-nano tapered fiber 24 is connected to the second single-mode fiber attenuator 233, and the U-shaped bottom end of the second micro-nano tapered fiber is in contact coupling with the measurement microdisk 14 in the opto-mechanical microcavity structure, so as to couple the second signal light into the opto-mechanical microcavity structure as the detection signal light, which is shown in fig. 6. In order to enable laser transmitted in the micro cavity of the optical mechanical system to well enter the cavity region and effectively collect signal light coupled out of the cavity, the U-shaped first micro-nano tapered fiber 22 and the U-shaped second micro-nano tapered fiber 24 with the micro-concave structure have the advantages of low transmission loss, high coupling efficiency and the like, and the position and the coupling length between the optical fiber and the micro cavity can be effectively adjusted through the design of the micro-concave structure.
The photoelectric detector 26 is connected to the first micro-nano tapered fiber 22 and the second micro-nano tapered fiber 24, and is configured to perform photoelectric conversion so as to convert the pump signal light into a first voltage signal and convert the detection signal light into a second voltage signal.
In this embodiment, the display unit 27 is a computer and is used for displaying the test result. The high-speed data acquisition card 28 is connected to the photodetector 26, the first signal output element, the second signal output element, and the display unit 27, and is configured to synchronize the first voltage signal with the first signal output element and the second signal output element, and then display the optical resonance mode of the opto-mechanical microcavity structure by the display unit 27. The real-time signal analyzer 29 is connected to the photodetector 26 and the display unit 27, and is configured to obtain the mechanical resonance characteristic of the mechanical oscillator of the opto-mechanical microcavity structure according to the second voltage signal, and display the characteristic through the display unit 27.
In addition, the testing of the opto-mechanical microcavity structure needs to be done in a vacuum to better observe the opto-mechanical coupling phenomenon. The test system in this embodiment therefore further comprises a vacuum device detection unit 25. Referring to fig. 7, the vacuum device detection unit 25 includes a vacuum box 251, and a first micro-nano displacement platform 252, a second micro-nano displacement platform 253, and a third micro-nano displacement platform 254 which are arranged in the vacuum box 251, wherein the first micro-nano displacement platform 252, the second micro-nano displacement platform 253, and the third micro-nano displacement platform 254 are high-precision micro-nano displacement control consoles for respectively controlling the position triaxial movement and the accurate alignment of the first micro-nano tapered fiber 22 serving as the pumping signal light, the opto-mechanical microcavity structure, and the second micro-nano tapered fiber 24 serving as the detection signal light. Specifically, the first micro-nano tapered fiber 22 is fixed on the first micro-nano displacement platform 252 through a first fiber fixing clamp 255, the second micro-nano tapered fiber 24 is fixed on the second micro-nano displacement platform 253 through a second fiber fixing clamp 256, and the chip 258 to be tested loaded with the opto-mechanical microcavity structure is fixed on the third micro-nano displacement platform 254 through a chip fixing platform 257 to be tested.
The specific process of the measuring system is as follows:
narrow-linewidth laser emitted by a first tunable narrow-linewidth laser 211 enters a mechanical first optical fiber polarization controller 212 through a single-mode optical fiber to perform polarization mode adjustment and selection, then is input into a first single-mode optical fiber attenuator 213, and then enters a first micro-nano tapered optical fiber 22 as pump light, and under the assistance of a first micro-nano displacement platform 252 and microscopic equipment such as a high-power optical microscope 30 and a high-resolution CCD camera 31, the first micro-nano tapered optical fiber 22 is in contact with a fixed first micro-nano beam 10 to excite light-cavity optical force in a mechanical coupling phenomenon;
narrow-linewidth laser emitted by the second tunable narrow-linewidth laser 231 enters the mechanical second optical fiber polarization controller 232 through the single-mode fiber to perform polarization mode adjustment and selection, then is input into the second single-mode fiber attenuator 233, and then enters the second micro-nano tapered fiber 24 as probe light, and under the assistance of the second micro-nano displacement platform 253, the high-power optical microscope 30, the high-resolution CCD camera 31 and other microscopic equipment, the second micro-nano tapered fiber 24 is in contact with the edge of the suspended measurement micro-disk 14 to measure the movement of the micro-nano probe 131, so that the observation of the nonlinear characteristic of the nonlinear mechanical oscillator 13 in the optical mechanical microcavity is realized.
As shown in fig. 8, this embodiment further discloses a testing method of the testing system, which includes the following steps:
step 1, assembling each part of the test system, and opening a first tunable narrow linewidth laser 211, a second tunable narrow linewidth laser 231, a high-power optical microscope 30, a high-resolution CCD camera 31, a photoelectric detector 26, a high-speed data acquisition card 28, a computer and a real-time signal analyzer 29 in sequence; the first micro-nano tapered fiber 22 and the second micro-nano tapered fiber 24 are respectively fixed on the first fiber fixing clamp 255 and the second fiber fixing clamp 256 through the UV glue 43. Referring to fig. 9, taking the first micro-nano tapered fiber 22 as an example: polishing a cylindrical 2B pen core with the diameter of 0.5cm into a wedge-shaped needle-shaped head 41 with the width of 8 mu m, slightly pressing and pressing the wedge-shaped needle-shaped head 41 at the middle positions of the first micro-nano tapered optical fiber 22 and the second micro-nano tapered optical fiber 24 with the aid of a mechanical displacement table, burning the pressing point by using a flame of a tiny alcohol lamp 42 for 1-2 seconds, withdrawing, and finally slightly separating the first micro-nano tapered optical fiber 22 and the second micro-nano tapered optical fiber 24 from the wedge-shaped needle-shaped head 41; in the air environment, the air conditioner is arranged,operating a first micro-nano displacement platform 252, a second micro-nano displacement platform 253 and a third micro-nano displacement platform 254, and completing physical coupling operation between the first micro-nano tapered optical fiber 22 and the first micro-nano beam 10 and between the second micro-nano tapered optical fiber 24 and the measurement micro disc 14 with the assistance of the high-power optical microscope 30 and the high-resolution CCD camera 31; then, the vacuum pump is opened to perform air extraction treatment on the vacuum box 251, and in the testing process, the pressure in the vacuum box 251 can reach 6.5
。
Step 3, arranging the first tunable narrow linewidth laser 211 at a half-wave position of an optical resonance peak to test a mechanical resonance mode in the opto-mechanical microcavity; particularly, it should be noted that, as simulation results show that only the transverse electric field even mode exists in the air gap 16 between the first micro-nano beam 10 and the second micro-nano beam 11, in order to obtain a larger cavity optical power in the opto-mechanical microcavity due to the optical gradient force, the cavity optical power is effectively applied to the movable second micro-nano beam 11, and in experimental tests, the TE of the optical fundamental mode resonance mode is selected1,eOr TE2,eA mechanical resonance mode test was performed. Further, TE due to the optical resonance mode1,eThe excitation light-mechanical coupling effect can be maximized by the high optical field energy and the optical field distribution existing in the air gap 16 between the first micro-nano beam 10 and the second micro-nano beam 11, so that the blue detuning half-wave position under the optical resonance mode is selected during the test of the embodiment, that is, the output wavelength of the first tunable narrow linewidth laser 211 is set to 1561.982nm, and the test of the mechanical oscillator resonance characteristic is performed by the real-time signal analyzer 29. As shown in fig. 11, the test result shows that the mechanical resonance frequencies are 10.22MHz (after being checked with the simulated mechanical frequency, the frequency can be determined to be the fundamental frequency of the nonlinear mechanical oscillator 13) and 13.54MHz (after being checked with the simulated mechanical frequency, the frequency can be determined to be the fundamental frequency of the linear mechanical oscillator 12), respectively. Meanwhile, because the air damping is greatly reduced or even disappears in the vacuum environment, good mechanical quality of the mechanical resonant cavity can be obtained, namely the mechanical Q value (the mechanical Q is equal to the mechanical resonance peak frequency divided by the mechanical line width) reaches 6.8
And 9.0
. The test result shows that the cavity optical force is excited in the optical mechanical microcavity, and the nonlinear mechanical vibrator 13 and the linear mechanical vibrator 12 are driven by the cavity optical force, so that the optical mechanical microcavity can be used for generating the nonlinear mechanical vibrationThe method is used for observing the vibration characteristics of the nonlinear mechanical oscillator 13.
And 4, scanning the microcavity of the measuring microdisk 14 by using a second tunable narrow linewidth laser 231 within the wavelength range of 1500nm-1620nm to obtain the wavelength shift of the optical resonance peak of the microcavity so as to monitor the displacement of the micro-nano probe arranged on the nonlinear mechanical vibrator 13. At this time, the pump signal light needs to be arranged in the TE of the coupled one-dimensional photonic crystal microcavity (i.e. the first micro-nano beam 10 and the second micro-nano beam 11)1,eThe blue detuned half-wave position of the optical resonance peak to excite the strongest optical force to drive the in-plane motion of the mechanical vibrator. The second tunable narrow linewidth laser 231 as the scanning parameter of the probe signal light is also set as: the wavelength scanning speed was 1 nm/sec and the wavelength scanning step was 1 pm. The scanning of the second tunable narrow linewidth laser 231 and the high-speed data acquisition card 28 need to set signal synchronization, and then realize the acquisition of the light intensity coupled out of the microcavity of the measurement microdisk 14 to acquire the optical resonance mode. As shown in fig. 12, in the static test, the optical resonance mode for measuring the microcavity of the microdisk 14 has several resonance peaks in the wavelength scanning range, the free spectral range between two adjacent resonance peaks is about FSR =11.1nm, the resonance peaks have good optical quality, and the optical Q value obtained by the test reaches 1.6
. Therefore, the wavelength shift of the optical resonance peak of the measurement microdisk 14 can satisfy the displacement measurement of the nonlinear mechanical vibrator 13 with the accuracy of 1 nm. When cavity optical force is applied to the mechanical vibrator, wavelength shift generated by a resonance peak of the micro-cavity of the micro-disk 14 is measured, and therefore displacement characteristic detection of the nonlinear optical mechanical system under cavity optical force driving is achieved.
And 5, observing the nonlinear displacement of the nonlinear mechanical vibrator 13 by using a modulated cavity optical force near the eigenfrequency of the nonlinear mechanical vibrator 13 of 10.22 MHz. The modulation of the cavity optical power is achieved by modulating the amplitude of the pump signal light. The specific method is to use a signal generator 32 to input a square wave excitation signal with the level amplitude of 5Vpp and the frequency set to be about 10.22MHz for scanning to enter a first tunable narrow linewidth laserExternal modulation interface of the device 211 in the optical resonance mode TE1,eBlue detuning half-wave position of; the detection signal light is used for monitoring the resonance peak wavelength of the measurement microdisk 14, as shown in fig. 13, when the pumping light intensity is lower than 10 μ W, the displacement characteristic of the nonlinear mechanical vibrator 13 does not have nonlinear displacement characteristics at the eigen frequency, however, when the pumping light intensity is increased to 125 μ W, the nonlinear mechanical vibrator 13 has an obvious Duffing vibration phenomenon, and displacement jump and hysteresis phenomena occur as the driving frequency of the strong light force approaches and leaves the eigen frequency.
Referring to fig. 14, when the above-mentioned photonic crystal optomechanical microcavity structure design containing the nonlinear mechanical oscillator 13 and the measurement system thereof are tested, the first tunable narrow linewidth laser 211 as the pump signal light is in the optical resonance mode TE1,eAnd then output with the light intensity of 50 muW, and the real-time signal analyzer 29 scans the intrinsic resonance frequency positions of the linear mechanical vibrator 12 and the nonlinear mechanical vibrator 13. When the detuning rate of the first tunable narrow linewidth laser 211 is gradually changed to be at the blue detuning position or the red detuning position, respectively, the mechanical resonance characteristic of the opto-mechanical microcavity follows the optical spring and damping phenomenon; however, when the detuning rate is at the position of the resonance peak and most of the optical field is limited in the optical cavity, after the harmonic frequency division phenomena such as 1/6, 1/32 and the like occur in the linear mechanical oscillator 12 and the nonlinear mechanical oscillator 13, a large amount of frequency modulation frequency division signals with 80.2kHz and reduced signal-to-noise ratio occur in two eigenfrequencies, the harmonic frequency division signals are generated by the nonlinear cavity optical force generated under the strong optical-mechanical coupling action, and the occurrence of the harmonic frequency division signals of the mechanical oscillator proves the nonlinear characteristic of the nonlinear mechanical oscillator 13 in the optical-mechanical microcavity from the optical-mechanical coupling action perspective.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. The photomechanical microcavity structure containing the nonlinear mechanical vibrator is characterized by comprising a silicon base, a first micro-nano beam, a second micro-nano beam, a linear mechanical vibrator, a nonlinear mechanical vibrator and a measuring micro-disc, wherein the first micro-nano beam, the second micro-nano beam, the linear mechanical vibrator, the nonlinear mechanical vibrator and the measuring micro-disc are positioned on the same plane;
the two ends of the first micro-nano beam and the two ends of the linear mechanical vibrator are both connected with the silicon base, the second micro-nano beam is fixedly connected to one side of the linear mechanical vibrator, an air gap is formed between the second micro-nano beam and the first micro-nano beam, and a second air groove is formed between the second micro-nano beam and the linear mechanical vibrator;
the nonlinear mechanical vibrator comprises at least two curve arms which are connected in series at the other side of the linear mechanical vibrator, a mass block is arranged in the middle of each curve arm, a micro-nano probe is arranged on each mass block, the measuring micro disc is arranged at a position adjacent to the micro-nano probe, and a first air groove is formed between the measuring micro disc and the micro-nano probe;
the curve line type of the curve arm is as follows:
in the formula (I), the compound is shown in the specification,hthe pre-bent height of the curved arm is shown,lrepresents the length of the curvilinear arm;
the bottoms of the first micro-nano beam, the second micro-nano beam, the linear mechanical vibrator and the nonlinear mechanical vibrator are all suspended.
2. The opto-mechanical microcavity structure containing a nonlinear mechanical vibrator according to claim 1, wherein the optical structures and the geometric dimensions of the first micro-nano beam and the second micro-nano beam are the same;
a plurality of air through holes are formed in the first micro-nano beam at intervals along the length direction, and the aperture of the air through hole in the defect area of the first micro-nano beam is gradually reduced along the direction from the middle to the two ends;
the aperture of the air through hole in the reflection area of the first micro-nano beam is equal to the minimum aperture of the air through hole in the defect area of the first micro-nano beam.
3. The photomechanical microcavity structure containing a nonlinear mechanical vibrator of claim 2, wherein the radius of the air through hole of the defect region on the first micro-nano beam is from the central hole r0Holes r gradually changing to two ends in the length of =127.9nm7=105.3nm；
The radius of the air through holes of the two reflecting regions on the first micro-nano beam is 105.3nm, and the distance between any two adjacent air through holes on the first micro-nano beam is equal to the lattice constant of 364.8 nm;
the initial width of the air gap between the second micro-nano beam and the first micro-nano beam is 125 nm.
4. A system for testing an opto-mechanical microcavity structure containing a nonlinear mechanical resonator according to any of claims 1 to 3, comprising:
a first signal output component for outputting a first signal light;
the first micro-nano tapered optical fiber is connected with the first signal output assembly, is in contact connection with a first micro-nano beam in the opto-mechanical microcavity structure, and is used for coupling the first signal light into the opto-mechanical microcavity structure to serve as pumping signal light;
a second signal output component for outputting a second signal light;
the second micro-nano tapered optical fiber is connected with the second signal output assembly, is in contact connection with a measuring micro-disc in the opto-mechanical microcavity structure, and is used for coupling the second signal light into the opto-mechanical microcavity structure to serve as detection signal light;
the photoelectric detector is connected with the first micro-nano tapered optical fiber and the second micro-nano tapered optical fiber and used for performing photoelectric conversion so as to convert the pumping signal light into a first voltage signal and convert the detection signal light into a second voltage signal;
the display unit is used for displaying the test result;
the high-speed data acquisition card is connected with the photoelectric detector, the first signal output component, the second signal output component and the display unit and is used for synchronizing a first voltage signal with the first signal output component and the second signal output component and then displaying an optical resonance mode of the opto-mechanical microcavity structure by the display unit;
and the real-time signal analyzer is connected with the photoelectric detector and the display unit and is used for obtaining the mechanical resonance characteristic of the mechanical oscillator of the opto-mechanical microcavity structure according to the second voltage signal and displaying the mechanical resonance characteristic through the display unit.
5. The test system according to claim 4, further comprising a vacuum device detection unit, wherein the vacuum device detection unit comprises a vacuum box, and a first micro-nano displacement platform, a second micro-nano displacement platform and a third micro-nano displacement platform which are arranged in the vacuum box;
the first micro-nano tapered fiber is fixed on the first micro-nano displacement platform through a first fiber fixing clamp, the second micro-nano tapered fiber is fixed on the second micro-nano displacement platform through a second fiber fixing clamp, and the opto-mechanical microcavity structure is fixed on the third micro-nano displacement platform through a chip fixing platform to be detected.
6. The test system according to claim 5, wherein the first micro-nano tapered fiber and the second micro-nano tapered fiber are both U-shaped micro-nano tapered fibers with a dimple, and the central core diameter of the U-shaped micro-nano tapered fibers is less than 1.5 μm from standard single-mode fiber hot melting tapering.
7. The test system according to claim 5 or 6, wherein the first signal output component comprises a first tunable narrow linewidth laser, a first optical fiber polarization controller, a first single-mode optical fiber attenuator, which are connected in sequence through an optical fiber;
the second signal output assembly comprises a second tunable narrow-linewidth laser, a second optical fiber polarization controller and a second single-mode optical fiber attenuator which are sequentially connected through optical fibers;
the first tunable narrow-linewidth laser and the second tunable narrow-linewidth laser work in a C wave band, the output light wavelength is 1500.00-1620.00 nm, the light source output power of the first tunable narrow-linewidth laser is 150 muW to ensure that strong enough cavity optical force is generated to drive a mechanical oscillator, and the light source output power of the second tunable narrow-linewidth laser is 30 muW to avoid a nonlinear effect caused by a thermo-optical effect.
8. A method for testing the test system of claim 7, comprising the steps of:
step 1, assembling and opening each part of a test system, and finishing physical coupling operation between a first micro-nano tapered fiber and a first micro-nano beam and between a second micro-nano tapered fiber and a measurement micro disc in an air environment; then the vacuum box is pumped until the pressure in the vacuum box reaches 6.5
；
Step 2, scanning spectrum of the opto-mechanical microcavity structure by utilizing a first tunable narrow-linewidth laser within the wavelength range of 1500nm-1620nm to obtain an optical resonant cavity mode of the opto-mechanical microcavity structure;
step 3, arranging the first tunable narrow linewidth laser at the half-wave position of the optical resonance peak to test the mechanical resonance mode in the opto-mechanical microcavity;
step 4, scanning the measured micro-disc by using a second tunable narrow linewidth laser within the wavelength range of 1500nm-1620nm to obtain the wavelength shift of an optical resonance peak of the measured micro-disc so as to monitor the displacement of the micro-nano probe arranged on the nonlinear mechanical vibrator;
and 5, carrying out intensity modulation on the cavity optical force for driving the nonlinear mechanical vibrator to move so as to measure the nonlinear characteristic of the nonlinear mechanical vibrator.
9. The testing method according to claim 8, wherein in step 1, the physical coupling operation between the first micro-nano tapered fiber and the first micro-nano beam and between the second micro-nano tapered fiber and the measurement micro-disc is completed, specifically:
fixing the first micro-nano tapered optical fiber and the second micro-nano tapered optical fiber on a first optical fiber fixing clamp and a second optical fiber fixing clamp respectively through UV glue;
polishing a cylindrical 2B pen core with the diameter of 0.5cm into a wedge-shaped needle-shaped head with the width of 8 mu m, pressing and pressing the wedge-shaped needle-shaped head at the middle positions of a first micro-nano tapered optical fiber and a second micro-nano tapered optical fiber with the assistance of a mechanical displacement table, burning the pressing point by using a micro alcohol lamp flame for 1-2 seconds, withdrawing, and finally separating the first micro-nano tapered optical fiber and the second micro-nano tapered optical fiber from the wedge-shaped needle-shaped head;
and finishing physical coupling operation between the first micro-nano tapered fiber and the first micro-nano beam and between the second micro-nano tapered fiber and the measuring micro disc with the assistance of a high-power optical microscope and a high-resolution CCD camera.
10. The testing method according to claim 8, wherein step 5 specifically comprises:
inputting a square wave excitation signal with the level amplitude of 5Vpp and the frequency set to be near 10.22MHz for scanning by a signal generator through an external voltage driving port of a first tunable narrow-linewidth laser;
after the intensity of the square wave excitation signal is modulated, the cavity optical force applied to the nonlinear mechanical vibrator is also modulated by the square wave excitation signal;
and detecting the resonance peak wavelength of the measurement microdisk by using detection signal light output by the second tunable narrow-linewidth laser.
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Inventor after: Xia Ji Inventor after: Wang Fuyin Inventor after: Chen Hu Inventor after: Hou Qingkai Inventor after: Loukang Inventor after: Wang Jianfei Inventor after: Hu Zhengliang Inventor after: Zhu Min Inventor after: Xiong Shuidong Inventor before: Xia Ji Inventor before: Wang Fuyin Inventor before: Chen Hu Inventor before: Hou Qingkai Inventor before: Loukang Inventor before: Wang Jianfei Inventor before: Hu Zhenliang Inventor before: Zhu Min Inventor before: Xiong Shuidong |