Integrated optical tweezers

Abstract

The present invention discloses an integrated optical tweezers, comprising: a gain chip, used to serve as a laser gain source in an external cavity laser system; a silicon-based optical chip and the gain chip are heterogeneously integrated; the silicon-based optical chip includes a 2×2 multimode interference coupler, a microring filter, multiple 1×2 multimode interference couplers, and multiple antenna transmission array elements; an end-face coupler of the silicon-based optical chip is connected to the output end of the gain chip, used to receive the light beam generated by the gain chip and transmit it to the microring filter through the 2×2 multimode interference coupler for filtering, thereby adjusting the beam wavelength; the filtered light beam passes through multiple 1×2 multimode interference couplers for average beam energy splitting; the split light beam is then phase-adjusted by the antenna transmission array element and transmitted into space through a grating antenna structure. The present invention enables more precise control of the optical potential well.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon-based optoelectronics. More specifically, the present invention relates to an integrated optical system for optical capture and manipulation based on a silicon-based optical chip. Background Art

[0002] Traditional optical tweezers systems rely on bulky optical components and are typically used for contactless manipulation of microparticles and cells. However, they are costly, complex, and require sophisticated laboratory equipment. This limitation has limited their widespread application. Previous optical tweezers technologies have been either complex and bulky, or have limited capture distances and insufficient dynamic manipulation capabilities, making it difficult to achieve precise, non-mechanical manipulation of targets.

[0003] Integrated optical tweezers offer the potential to address these issues and enable compact, low-cost optical manipulation systems. However, previous integrated optical tweezers technologies were primarily limited to micrometer-scale working distances near the chip surface, and most were passive trapping functions, limiting their applicability in cell experiments. Summary of the Invention

[0004] In view of this, the present invention proposes an integrated optical tweezers, which can achieve more precise control of the optical potential well.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides an integrated optical tweezers, comprising:

[0007] Gain chip, used to act as a laser gain source in an external cavity laser system;

[0008] The silicon-based optical chip is integrated with the gain chip in a heterogeneous manner;

[0009] The silicon-based optical chip includes an end-face coupler, a 2×2 multimode interference coupler, a microring filter, multiple 1×2 multimode interference couplers, and multiple antenna transmitting array elements;

[0010] The end coupler is connected to the output end of the gain chip, and is used to receive the light beam generated by the gain chip and transmit it to the 2×2 multimode interference coupler, and then transmit it to the microring filter for filtering to adjust the wavelength of the light beam;

[0011] The filtered beam passes through multiple 1×2 multimode interference couplers to averagely split the beam energy;

[0012] The split light beam is emitted into space through the grating antenna structure after the phase is adjusted by the antenna transmitting array element.

[0013] Preferably, the gain chip includes a gain chip electrode and a gain chip body, wherein:

[0014] By injecting current into the gain chip electrodes, the gain chip body enters the working state;

[0015] One end face of the gain chip body is coated with a high reflectivity, and the other end face is coated with a reflective coating with a slightly lower reflectivity. The light beam generated by the gain chip is output through the reflective end face with a slightly lower reflectivity and is coupled to the outside through a curved waveguide.

[0016] Preferably, the silicon-based optical chip further includes an end coupler, and the end coupler adopts a silicon waveguide Taper structure;

[0017] The end coupler and the gain chip perform mode field matching to introduce the light beam generated by the gain chip;

[0018] The end coupler uses a preset tilt angle to prevent reflected light from entering during the end coupling process.

[0019] Preferably, the microring filter comprises:

[0020] Silicon-based waveguides, either straight or curved;

[0021] The microring resonator includes a microring waveguide structure, a titanium nitride structure having a shape similar to that of the microring waveguide structure and a wider width is provided above the microring waveguide structure, a box layer made of silicon dioxide material is provided below the microring waveguide structure, and a silicon-based substrate is provided below the box layer;

[0022] A microring filter control electrode, used for receiving an external current and loading it into a titanium nitride structure in the microring resonator;

[0023] When the titanium nitride structure is heated by the current, it changes the local temperature field, which in turn changes the effective refractive index of the microring waveguide structure, thereby changing the resonant wavelength of the light beam to adjust the output wavelength of the light beam.

[0024] The dispersion direction of the grating antenna structure is controlled by adjusting the output wavelength of the light beam, thereby controlling the focal position of the light beam in the X direction.

[0025] Preferably, the antenna transmitting array element includes:

[0026] The MZI structure is composed of two 1×2 MMI multimode interference couplers and a first-class phase shifter. The first-class phase shifter changes the phase of the light beam in one of the waveguides, and the energy of the output beam is controlled by interference.

[0027] The second type of phase shifter is provided at the output end of the MZI structure and is used to control the phase of the light beam input to the grating antenna structure, so as to control the position of the grating antenna structure in the near field coherent phase, and thus control the focal position;

[0028] The grating antenna structure consists of a silicon-based waveguide and is a periodic winding structure.

[0029] Preferably, a type of phase shifter includes a thermo-optical based phase shifter or an electro-optical based phase shifter;

[0030] Thermo-optical phase shifters control the optical phase by changing the local temperature and thus the local effective refractive index;

[0031] Electro-optical phase shifters control the optical phase by changing the effective refractive index by varying the carrier concentration;

[0032] Phase shifter electrodes provided in a type of phase shifter receive externally applied voltage or current to change the local temperature or carrier concentration.

[0033] Preferably, multiple grating antenna structures corresponding to multiple antenna transmitting elements are combined into an array antenna, and the coherent position of the light beam in the Y direction is controlled by adjusting the phase of the light beam through the second type phase shifter corresponding to each grating antenna structure in the array antenna.

[0034] Preferably, the near-field electric field distribution generated by the light beam emitted into space by the silicon-based optical chip is approximated by a near-field quasi-array factor model:

[0035]

[0036] in, represents the total number of arrays of grating antenna structures, represents the amplitude of the nth grating antenna structure, Indicates the nth grating antenna structure to the target focus distance, is the wavelength transmitted in the optical waveguide, The phase that needs to be adjusted for the n-th grating antenna structure;

[0037]

[0038] When using a lens-like hyperbolic element phase distribution, the distance from the nth grating antenna structure to the focus The calculation is as follows:

[0039]

[0040] in, Indicates the desired focal length.

[0041] The present invention has achieved at least the following beneficial effects:

[0042] 1. Realizing on-chip control of light gradient force and radiation pressure, and combining it with existing CMOS chip technology, can significantly reduce system size and cost, and provide greater flexibility for optical tweezers technology to achieve non-contact capture and manipulation of tiny particles or cells through focused light beams.

[0043] 2. By adjusting the microring resonator and the second-type phase shifter, the wavelength and phase of the light wave can be precisely controlled. By controlling the first-type phase shifter, the amplitude of each antenna can be precisely controlled, thereby controlling the gradient force and radiation pressure of the light, achieving high-precision dynamic optical capture.

[0044] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to make the purpose, technical solutions and beneficial effects of the present invention more clear, the present invention provides the following drawings for illustration:

[0046] Figure 1 Schematic diagram of the structure of an integrated optical tweezers according to an embodiment of the present invention;

[0047] Figure 2 2×2 MMI structure in an embodiment of the present invention;

[0048] Figure 3 Schematic diagram of the longitudinal structure of a microring resonator in an embodiment of the present invention;

[0049] Figure 4 Schematic diagram of the structure of a thermo-optical phase shifter according to an embodiment of the present invention;

[0050] Figure 5 Schematic diagram of the structure of an electro-optical phase shifter according to an embodiment of the present invention;

[0051] Figure 6 Schematic diagram of the structure of the MZI in an embodiment of the present invention;

[0052] Figure 7 This is a partially enlarged view of the grating antenna structure in an embodiment of the present invention.

[0053] In the figure, 1. gain chip; 101. gain chip electrode; 102. gain chip body; 201. end coupler; 202. 2×2 multimode interference coupler; 203. silicon-based waveguide; 204. microring resonator; 205. microring filter control electrode; 206. 1×2 MMI multimode interference coupler; 207. phase shifter electrode; 208. Type I phase shifter; 209. Type II phase shifter; 210. grating antenna structure. DETAILED DESCRIPTION

[0054] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0055] The present invention provides an integrated optical tweezers, comprising:

[0056] Gain chip 1, used to serve as a laser gain source in an external cavity laser system;

[0057] The silicon-based optical chip 2 is integrated with the gain chip 1 in a heterogeneous manner;

[0058] The silicon-based optical chip 2 includes an end face coupler 201, a 2×2 multimode interference coupler 202, a micro-ring filter, multiple 1×2 multimode interference couplers 206, and multiple antenna transmitting array elements;

[0059] The end coupler 201 is connected to the output end of the gain chip 1, and is used to receive the light beam generated by the gain chip 1 and transmit it to the 2×2 multimode interference coupler 202, and then transmit it to the microring filter for filtering to adjust the wavelength of the light beam;

[0060] The filtered light beam passes through multiple 1×2 multimode interference couplers 206 to averagely split the beam energy;

[0061] The split light beam is emitted into space through the grating antenna structure 210 after the antenna transmitting array element adjusts the phase.

[0062] The working principle and beneficial effects of the above technical solution are as follows: Utilizing silicon-based optoelectronics technology, a method is proposed to control the output wavelength by adjusting the parameters of a microring filter, and thus the electronically controlled phase modulator to control the focal position in the x and y planes. Simultaneously, an MZI (Mach-Zehnder Interferometer) structure is introduced before each antenna to achieve arbitrary control of the antenna's radiated energy distribution. This allows for the application of a specific power attenuation pattern within the array, reducing sidelobe intensity and concentrating more energy on the main beam. This structure and control method enable more precise control of the optical potential well.

[0063] In a specific embodiment, referring to Figure 1The silicon-based optical chip 2 and the gain chip 1 are heterogeneously integrated. The light generated by the gain chip body 102 is coupled into the silicon photonic chip through the end coupler 201 by receiving external current from the gain chip electrode 101. The end coupler 201 is angled to reduce reflection. The coupled light is output to the silicon-based waveguide 203 through one port of the 2×2 multimode interference coupler 202 (2×2 MMI). The silicon-based waveguide 203 is a curved coupled waveguide and is coupled into the microring resonator 204. The microring resonator 204 generally has a TiN (titanium nitride) thermal controller added above its microring waveguide structure. Injecting current through the microring filter control electrode 205 can change the local temperature to adjust the filtering parameters. The filtered beam is output through one port of the 2×2 multimode interference coupler 202 structure to the first-stage 1×2 MMI (1×2 multimode interference coupler 206). Depending on the array size, the 1×2 multimode interference coupler 206 is used to evenly split the beam energy into subsequent antenna transmit elements. The final two stages of the 1×2 multimode interference coupler 206 employ an MZI structure, with a phase shifter (TiN thermally tunable electrode or PN junction phase shifter) incorporated into one arm, as shown in the first-stage phase shifter 208. The phase shifter electrode 207 receives an externally applied voltage or current, and the phase of the beam in the waveguide can be controlled by an external control circuit. After passing through the MZI structure, the output beam enters the final second-stage phase shifter 209, and is then emitted into space via the grating antenna structure 210.

[0064] The beneficial effects of the above technical solution are as follows: the present invention proposes a highly integrated optical tweezers system that can realize on-chip light gradient force and radiation pressure control, and combined with existing CMOS chip technology, it can greatly reduce the system volume and cost, and provide higher flexibility for optical tweezers technology to achieve non-contact capture and manipulation of tiny particles or cells by focusing light beams.

[0065] In a specific embodiment, the gain chip 1 includes a gain chip electrode 101 and a gain chip body 102, wherein:

[0066] By injecting current into the gain chip electrode 101, the gain chip body 102 enters the working state;

[0067] One end face of the gain chip body 102 is coated with a high reflectivity, and the other end face is coated with a reflective coating with a slightly lower reflectivity. The light beam generated by the gain chip is output through the reflective end face with a slightly lower reflectivity and is coupled to the outside through the curved waveguide.

[0068] In a specific embodiment, the silicon-based optical chip 2 further includes an end coupler 201, and the end coupler 201 adopts a silicon waveguide Taper structure;

[0069] The end coupler 201 performs mode field matching with the gain chip 1 to guide the light beam generated by the gain chip 1;

[0070] The end face coupler 201 adopts a preset tilt angle to prevent reflected light from entering during the end face coupling process.

[0071] In a specific embodiment, the microring filter includes:

[0072] The silicon-based waveguide 203 is a straight waveguide or a curved waveguide;

[0073] The microring resonator 204 includes a microring waveguide structure, a titanium nitride structure having a shape similar to that of the microring waveguide and a wider width is disposed above the microring waveguide structure, a box layer made of silicon dioxide material is disposed below the microring waveguide structure, and a silicon-based substrate is disposed below the box layer;

[0074] The microring filter control electrode 205 is used to receive external current and load it into the titanium nitride structure in the microring resonator 204;

[0075] When the titanium nitride structure is heated by the current, it changes the local temperature field, which in turn changes the effective refractive index of the microring waveguide structure, thereby changing the resonant wavelength of the light beam to adjust the output wavelength of the light beam.

[0076] The dispersion direction of the grating antenna structure 210 is controlled by adjusting the output wavelength of the light beam, thereby controlling the focal position of the light beam in the X direction.

[0077] In a specific embodiment, the antenna transmitting array element includes:

[0078] The MZI structure is composed of two 1×2 MMI multimode interference couplers and a first-class phase shifter 208. The first-class phase shifter 208 changes the phase of the light beam in one of the waveguides, thereby controlling the energy of the output light beam under the interference effect.

[0079] The second type of phase shifter 209 is provided at the output end of the MZI structure and is used to control the phase of the light beam input to the grating antenna structure 210, so as to control the position of the grating antenna structure 210 in the near field coherent phase, thereby controlling the focal position;

[0080] The grating antenna structure 210 is composed of a silicon-based waveguide and is a periodic surrounding structure.

[0081] In one specific embodiment, a type of phase shifter 208 includes a thermo-optical based phase shifter or an electro-optical based phase shifter;

[0082] Thermo-optical phase shifters control the optical phase by changing the local temperature and thus the local effective refractive index;

[0083] Electro-optical phase shifters control the optical phase by changing the effective refractive index by varying the carrier concentration;

[0084] The phase shifter electrodes 207 provided in the type of phase shifter 208 receive an externally applied voltage or current to change the local temperature or carrier concentration.

[0085] In a specific embodiment, multiple grating antenna structures 210 corresponding to multiple antenna transmitting elements are combined into an array antenna, and the coherent position of the light beam in the Y direction is controlled by adjusting the phase of the light beam through the second type phase shifter 209 corresponding to each grating antenna structure 210 in the array antenna.

[0086] In a specific embodiment, the near-field electric field distribution generated by the light beam emitted into space by the silicon-based optical chip 2 is approximated by a near-field quasi-array factor model:

[0087]

[0088] in, represents the total number of arrays of the grating antenna structure 210, represents the amplitude of the n-th grating antenna structure 210, Indicates the nth grating antenna structure 210 to the target focus distance, is the wavelength transmitted in the optical waveguide, is the phase that needs to be adjusted for the n-th grating antenna structure 210;

[0089]

[0090] When a lens-like hyperbolic element phase distribution is used, the distance from the nth grating antenna structure 210 to the focus is The calculation is as follows:

[0091]

[0092] in, Indicates the desired focal length.

[0093] The phase of the nth grating antenna structure 210 needs to be adjusted. The desired phase can be obtained by adjusting the second type phase shifter 209 structure, thereby obtaining the desired focus position. By adjusting the microring resonator 204 and the second type phase shifter 209, the wavelength and phase of the light wave can be precisely controlled. By controlling the first type phase shifter 208, the amplitude of each antenna can be precisely controlled. , and then control the gradient force and radiation pressure of light to achieve high-precision dynamic optical capture.

[0094] The structure in the embodiment of the present invention includes:

[0095] Gain Chip 1: The gain chip acts as the laser gain source in the external cavity laser system;

[0096] Gain chip electrode 101: inject current through the electrode to put the gain chip into working state;

[0097] Gain chip body 102: The left end face has a high reflectivity (HR) coating, and the other inclined end face has a low reflectivity (AR) coating. The light beam generated by the gain chip is output through the waveguide with the inclined right end face;

[0098] Silicon-based chip 2: Made of SOI wafer;

[0099] End coupler 201: This uses a silicon waveguide tapered structure to perform mode field matching with the gain chip, directing the light beam into the silicon photonic chip. In this example, the end coupler is tilted to prevent reflected light from entering the chip during the end coupling process.

[0100] 2×2 multimode interference coupler 202: 2×2MMI, structure reference Figure 2 , light enters from port 1, is output from ports 2 and 3 to the microring filter, and the filtered light beam is output from port 4 to the subsequent optical path;

[0101] Silicon-based waveguide 203: can be a straight waveguide or a curved waveguide. In the example, an ultra-sharp curved waveguide is used to increase the tunable wavelength range.

[0102] Microring resonator 204: Its longitudinal structure is as follows Figure 3 As shown, titanium nitride is used above the microring waveguide, and its shape is similar to that of the microring, with a width of approximately 100 mm.

[0103] Microring filter control electrode 205: Current is injected from the electrode into the titanium nitride in the microring resonator 204. The titanium nitride will generate heat, thereby changing the local temperature field and further changing the effective refractive index of the microring waveguide. , where R is the radius of the microring, m is a positive integer, is the effective refractive index. The change of the effective refractive index changes the resonant wavelength, thereby achieving the purpose of adjusting the output wavelength;

[0104] 1×2 multimode interference coupler 206: 1×2 MMI, splitting the light into two output ports with an energy ratio of 50:50;

[0105] Phase shifter electrode 207: connected to an external circuit, externally applied voltage or current;

[0106] A type of phase shifter 208: Silicon-based phase shifters mainly include thermo-optical phase shifters and electro-optical phase shifters. The schematic diagram of their structure is shown in the figure. Figure 4 and 5 As shown, the thermo-optical phase shifter changes the local temperature and thus the local effective refractive index to control the optical phase, while the electro-optical phase shifter changes the carrier concentration to change the effective refractive index and thus control the optical phase.

[0107] MZI structure (Mach-Zehnder interferometer): Figure 6 ,It is composed of two 1×2 MMIs, one phase shifter, and one straight waveguide that can be combined into an MZI structure.,By changing the phase in one of the waveguides in the MZI, the energy of the output light can be,controlled due to interference;

[0108] The second type of phase shifter 209 has the same structure as the first type of phase shifter 208. The phase shifter here controls the phase of the input to the grating antenna structure 210, which can control the position of the optical antenna in the near field coherent phase, and thus control the focal position;

[0109] Grating antenna structure 210: composed of silicon-based waveguide, its partial enlarged diagram refers to Figure 7 , which is a periodic surrounding structure, is composed of N antennas combined into an array antenna. By controlling and adjusting the phase in the second type phase shifter 209, the coherent position of the light beam in the Y direction can be controlled. By controlling the microring resonator 204, the wavelength can be controlled, thereby controlling the dispersion direction of the antenna and further controlling the focal position of the light beam in the X direction.

[0110] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. An integrated optical tweezers, characterized in that: include: A gain chip (1) is used to serve as a laser gain source in an external cavity laser system; A silicon-based optical chip (2) is integrated with a gain chip (1) in a heterogeneous manner; The silicon-based optical chip (2) includes an end face coupler (201), a 2×2 multimode interference coupler (202), a micro-ring filter, a plurality of 1×2 multimode interference couplers (206), and a plurality of antenna transmission array elements; The end face coupler (201) is connected to the output end of the gain chip (1) and is used to receive the light beam generated by the gain chip (1) and transmit it to the 2×2 multimode interference coupler (202), and then transmit it to the micro-ring filter for filtering to adjust the wavelength of the light beam; The filtered light beam passes through a plurality of 1×2 multimode interference couplers (206) to perform average beam splitting of the light beam energy; The split light beam is emitted into space through the grating antenna structure (210) after the phase is adjusted by the antenna transmitting array element; The gain chip (1) comprises a gain chip electrode (101) and a gain chip body (102), wherein: By injecting current into the gain chip electrode (101), the gain chip body (102) enters a working state; One end face of the gain chip body (102) is provided with a high reflectivity coating, and the other end face is provided with a reflective coating with a slightly lower reflectivity. The light beam generated by the gain chip is output through the reflective end face with a slightly lower reflectivity and is coupled to the outside through a curved waveguide. Microring filters include: A silicon-based waveguide (203) is a straight waveguide or a curved waveguide; The microring resonator (204) comprises a microring waveguide structure, a titanium nitride structure having a shape similar to that of the microring waveguide structure and a wider width is provided above the microring waveguide structure, a Box layer made of silicon dioxide material is provided below the microring waveguide structure, and a silicon-based substrate is provided below the Box layer; A microring filter control electrode (205) is used to receive an external current and load it into the titanium nitride structure in the microring resonator (204); When the titanium nitride structure is heated by the current, it changes the local temperature field, which in turn changes the effective refractive index of the microring waveguide structure, thereby changing the resonant wavelength of the light beam to adjust the output wavelength of the light beam. The dispersion direction of the grating antenna structure (210) is controlled by adjusting the output wavelength of the light beam, thereby controlling the focal position of the light beam in the X direction; The antenna transmitting array elements include: The MZI structure is composed of two 1×2 MMI multimode interference couplers and a first-class phase shifter (208), and the phase of the light beam in one of the waveguides is changed by the first-class phase shifter (208), so as to control the energy of the output light beam under the interference effect; A second type of phase shifter (209) is provided at the output end of the MZI structure and is used to control the phase of the light beam input into the grating antenna structure (210), thereby controlling the position of the grating antenna structure (210) in the near field coherent phase, and further controlling the focal position; The grating antenna structure (210) is composed of a silicon-based waveguide and is a periodic surrounding structure.

2. An integrated optical tweezers according to claim 1, characterized in that, The end face coupler (201) adopts a silicon waveguide Taper structure; The end face coupler (201) and the gain chip (1) perform mode field matching to introduce the light beam generated by the gain chip (1); The end face coupler (201) adopts a preset tilt angle to prevent reflected light from entering during the end face coupling process.

3. The integrated optical tweezers according to claim 1, characterized in that: A type of phase shifter (208) includes a thermo-optical based phase shifter or an electro-optical based phase shifter; Thermo-optical phase shifters control the optical phase by changing the local temperature and thus the local effective refractive index; Electro-optical phase shifters control the optical phase by changing the effective refractive index by varying the carrier concentration; A phase shifter electrode (207) provided in a type of phase shifter (208) receives an externally applied voltage or current to change the local temperature or carrier concentration.

4. The integrated optical tweezers according to claim 1, characterized in that: Multiple grating antenna structures (210) corresponding to multiple antenna transmitting array elements are combined into an array antenna, and the coherent position of the light beam in the Y direction is controlled by adjusting the phase of the light beam through the second type phase shifter (209) corresponding to each grating antenna structure (210) in the array antenna.

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