CN116224507A - Space light receiving chip and photoelectric conversion chip of micro lens array auxiliary grating array - Google Patents

Abstract

The application discloses a space light receiving chip of microlens array auxiliary grating array, this chip includes two parts: microlens arrays and grating arrays. According to the method, the problem that the receiving aperture of the grating coupler in the integrated space light receiving chip is small is solved, refractive index distribution is adjusted through designing the micro-lens array subunit structure, spatial light modulation in a certain range can be used as focused light under the condition that design difficulty and cost are not greatly increased, the limitation of the original beam size is broken through, the receiving aperture is effectively increased, and therefore the receiving aperture efficiency of the grating coupler is improved, and efficient space light signal receiving and two-dimensional photoelectric conversion are achieved. The application also discloses a corresponding space light receiving and photoelectric conversion chip of the micro-lens array auxiliary grating array.

Description

Space light receiving chip and photoelectric conversion chip of micro lens array auxiliary grating array

Technical Field

The invention belongs to the technical field of communication, and particularly relates to a chip technology with high receiving aperture efficiency in the field of integrated microwave photons.

Background

Integrated microwave photon technology can implement complex and scalable optical signal processing including modulation, multiplexing, wavelength conversion, optical signal detection, and the like. The free space light beam is received through the integrated microwave photon technology, a compact, low-power-consumption, low-cost, multifunctional and highly-expandable optical signal processing mode is brought for the traditional free space optical application, and the method has wide application prospects in the fields of next-generation mobile communication (6G), three-dimensional optical information processing, simultaneous multi-beam receiving and the like. Compared with the traditional optical device, the integrated photonic device has the advantages that through integration and miniaturization, the volume and the power consumption of the system are greatly reduced, the cost of independently packaging each device is avoided, the coupling loss among the devices is reduced, the stability of the system is greatly improved, and the requirement of large-scale array application can be met.

However, as an important receiving unit of the photonic integrated chip, the optical field of the grating coupler decays exponentially, so when the detected spatial light range is enlarged to hundreds of micrometers, the transmission efficiency of the light beam, the range of the detected light, the spatial light phase and intensity distribution are greatly limited due to the small effective photosensitive area of the grating coupler and the relative fixity of the existing structural units, and large-aperture receiving cannot be realized. Based on the existing structure, the grating coupler structure is reasonably optimized on the basis of not greatly increasing the design and processing cost, so that the output light field can be intensively diffracted in a certain required direction, the coupling efficiency of the space light or chip optical waveguide transmission line to the light wave is improved, the compact and efficient mode conversion between the high-refractive-index optical waveguide transmission line and the free space light beam with wider size is ensured, and the realization of high-aperture-efficiency focusing and transmission is still a challenge.

Disclosure of Invention

An object of the present application is to provide an improved spatial light receiving chip, which solves the problem of low efficiency of the spatial light receiving aperture in the prior art, aiming at least one of the above technical problems.

To achieve the above object, some embodiments of the present application provide a spatial light receiving chip of a microlens array auxiliary grating array, which includes a microlens array located in an incident direction of the spatial light for converging the spatial light; a grating array on an exit light path of the spatial light through the microlens array, wherein the microlens array comprises a plurality of sub-units arranged in a period configured to converge a portion of the beam of the spatial light, one sub-unit of the microlens array overlying one grating coupler of the grating array such that each sub-unit of the microlens array converges a portion of the beam of the spatial light within an effective receiving aperture of its overlying grating coupler.

In some embodiments, each subunit of the microlens array is arranged in a periodic arrangement, each subunit being configured such that spatial light incident on the microlens array exits through the microlens array along an optical axis of each subunit to an effective aperture of the grating coupler.

In some embodiments, an optical waveguide transmission line is also included that transmits the output of the grating array outward.

In some embodiments, the subunit is a microlens or a super-structured lens.

In some embodiments, the microlens array includes a plurality of subunits arranged in a rectangular array;

in some embodiments, each of the sub-units has the same focal length and the focal points are on the same side such that the exit side of the microlens array forms a focal plane that is formed by the focal points of each sub-unit.

In some embodiments, the grating array is disposed on the focal plane of the microlens array, and the effective aperture of a single grating coupler in the grating array corresponds one-to-one to the size of the beam after converging the subunits.

In some embodiments, the microlens array and the grating array are configured such that the subunit converges the beam of spatial light into the effective receiving aperture of the grating coupler comprising the following configuration steps: determining a focusing light spot range of the light beam of the space light, which is emitted from each subunit and then enters the surface of the grating coupler; carrying out theoretical calculation according to the size of the focusing light spot range and the space light range received by the subunit to obtain the focal length and the numerical aperture of the subunit; determining the position relation between the micro lens array and the grating array according to the position of the focusing light spot on the grating coupler; coupling and aligning the micro lens array and the grating array according to the position relation; wherein the subunit is configured to receive a spatial light beam at a normal incidence.

In some embodiments, testing the existing structure of each grating coupler yields a movable receiving range with high coupling efficiency, so as to determine the light spot range of the light beam entering the surface of the grating coupler after exiting the corresponding subunit.

Other embodiments of the present application provide a spatial light receiving and photoelectric conversion chip of a microlens array auxiliary grating array, which includes a circuit board, on which the spatial light receiving chip of any one of the above microlens array auxiliary grating arrays is disposed; and the photoelectric detector arrays are arranged on the circuit board and are configured to convert the output of one grating coupler in the space light receiving chip of the micro lens array auxiliary grating array, which is transmitted by the optical waveguide transmission line, into a microwave signal by the photoelectric detector in each photoelectric detector array.

In some embodiments, the micro lens array assists the space light receiving and photoelectric conversion chip of the grating array further includes a radio frequency output end array, which is disposed on the circuit board, and is configured such that one of the radio frequency output ends is connected to one of the photodetectors in the photodetector array, so as to output the microwave signal received from the photodetector, transmit the intensity, amplitude and phase information of the space light, and realize the amplitude-phase detection of the space light.

The beneficial effects of the invention include, but are not limited to: the space light receiving chip of the micro lens array auxiliary grating array in some embodiments of the application converges vertical incidence space light on the basis of not greatly increasing design difficulty and cost, so that the vertical incidence space light is focused into an effective receiving aperture of a grating coupler, diffraction in a certain required direction is concentrated, light wave diffraction of the grating coupler in other directions is reduced, and coupling efficiency of the grating coupler is effectively increased. The space light receiving chip in some embodiments of the application utilizes the advantages of integrated photon high-speed parallel processing and transmission to construct the micro-lens array for space light information receiving, and is matched with the on-chip grating array, so that light beams are focused in the effective aperture of the grating array, the aperture efficiency of the receiving array is increased, the utilization rate of space light beams in the prior art is improved, and the space light receiving range is improved.

Drawings

FIG. 1A is a schematic diagram of an array structure of a spatial light receiving chip of a microlens array auxiliary grating array according to an embodiment of the present application;

FIG. 1B is a schematic diagram of an array structure of a spatial light receiving chip of a super-structured lens array auxiliary grating array according to an embodiment of the present application;

FIG. 2A is a schematic diagram of a grating coupler structure according to one embodiment;

FIG. 2B is a top view of a grating coupler structure according to another embodiment;

FIG. 3A is a schematic diagram showing an arrangement of a microlens array composed of conventional microlenses;

FIG. 3B is a schematic diagram showing an arrangement of microlens arrays of the super-structure lens;

FIG. 4A is a schematic view of the structure of a single conventional microlens of FIG. 3A;

FIG. 4B is a schematic diagram of the structure of the single super-lens of FIG. 3B;

fig. 5 is a schematic structural diagram of a chip assembly according to an embodiment of the present application.

In the accompanying drawings: a micro lens array 11, an ultra-structured lens array 12, a grating array 2, space light 3, a converging light beam 4, a photoelectric detector array 5, an optical waveguide transmission line 6, a radio frequency interface 7 and a circuit board 8

Detailed Description

The present invention is described in further detail below with reference to the drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it.

As shown in fig. 1A, an embodiment of a spatial light receiving chip of a microlens array auxiliary grating array according to the present application includes a microlens array composed of a plurality of conventional microlenses 11 as subunits for acquiring spatial light 3 incident from the microlens array; the grating array 2 is used to couple the received converging light signal 4 of each microlens to achieve high receiving aperture efficiency of signal reception.

As shown in fig. 1B, another embodiment of a spatial light receiving chip of a microlens array auxiliary grating array according to the present application includes a microlens array composed of a plurality of super-structured lenses 12 as sub-units for acquiring spatial light 3 incident by the microlens array; the grating array 2 is used to couple the received converging light signal 4 of each microlens to achieve high receiving aperture efficiency of signal reception.

The microlens arrays 11, 12 are configured to receive spatial light beams at normal incidence. The sub-units of the micro lens array are used for converging the signal light beams into the effective receiving apertures of the grating couplers in the grating array 2, so that the space light beams are further received efficiently. As described above, the microlens array is composed of sub-units, which may be conventional spherical and aspherical microlenses as shown in fig. 3A, or super-structured lenses formed of sub-wavelength nanostructures as shown in fig. 3B. For example, each subunit of the microlens array is arranged in a periodic arrangement, each subunit being configured such that spatial light incident on the microlens array passes through the microlens array and exits along the optical axis of each microlens to the effective aperture of the grating coupler.

The grating array, also called as grating coupler array, comprises a plurality of grating couplers serving as array elements, and has the advantages of being multiple in array element number, high in integration level, high in receiving aperture efficiency and the like. However, for grating coupler reception, there is a threshold value for the incident beam entering the grating coupler, and the coupling efficiency is reduced outside the effective reception range. It is therefore necessary that the grating array be matched to the microlens array to increase the coupling efficiency. Matching the array of grating couplers to the array of microlenses may include:

first, the existing structure of the grating coupler 21 in the grating array 2 is tested by using the space light 3, so as to obtain a movable receiving range with higher coupling efficiency of the grating coupler, for example, the area a defined by a to B in fig. 2B, thereby determining the focusing spot size of the light beam of the space light entering the corresponding grating coupler surface after exiting from the micro lens.

Then, theoretical calculation is carried out according to the space light received by the subunit and the space of the focusing light spot position on the rear surface of the lens

Wherein NA' is the numerical aperture, n is the refractive index of the lens working medium, for example, if the working medium is air, n=1.0, d is the lens size, f is the focal length of the subunit, and β is half of the maximum cone angle when the light exits the subunit of the microlens array, thereby obtaining the focal length and numerical aperture of the subunit;

and determining the position relation between the micro lens array and the grating array according to the position of the focusing light spot on the grating coupler. Wherein the position of the focused spot follows the gaussian lens formula:

where u is the distance of the incident beam from the front surface of the subunit of the microlens array, and u= infinity, v is the distance of the rear surface of the subunit exiting the surface of the grating coupler, taking the value f, because the incident beam is normally incident spatial light.

And finally, coupling and aligning the micro lens array and the grating array according to the position relation.

Fig. 3A is a schematic diagram showing an arrangement of a microlens array in which subunits are conventional microlenses. Fig. 3B is a schematic diagram showing the arrangement of a microlens array in which the subunits are super-lenses. The microlens array shown in either fig. 3A or fig. 3B may be arranged in a manner consisting of m×n subunits, each of which is a separate lens, each lens functioning to focus the light beam.

The m×n individual microlenses may be conventional spherical microlenses, conventional aspherical microlenses, or super-structured lenses as described above, and for a communication band (1550 nm), si may be selected as a material for the super-structured lenses, and silicon oxide may be selected as a material for the conventional microlenses, which has the characteristics of high transmittance and low loss in the corresponding band. The specific layout structure in implementation can flexibly layout the micro lens array according to practical application requirements.

The micro lens array is an array formed by a plurality of micro lenses, can simultaneously receive a plurality of signal beams, and can finish multi-beam simultaneous receiving by optical means, and the size of the micro lenses is matched with the effective aperture of the grating coupler. Each microlens in the microlens array is arranged in a period of the grating array, for example, in a rectangular array or a circumferential array according to the rectangular array or the circumferential array of the grating array. The microlens array is configured such that spatial light incident on the microlens array exits through the microlens array along the optical axis of each microlens to the effective aperture of the grating coupler.

As described above, the sub-units of the microlens array may be arranged in a rectangular distribution or distributed as a circumferential array according to the system requirements, realizing precise control of the phase per sub-unit structure, and improving the ability to focus light while reducing distortion.

Fig. 4A shows a three-dimensional structure of a spherical microlens as a subunit, which adopts a conventional optical lens, and has simple design and easy processing and preparation. Fig. 4B shows a three-dimensional structure of a super-structured lens with sub-units being super-structured lenses composed of polarization independent cylindrical nano-pillar structures, which have space size advantages, for normal incidence spatial light signals, to ensure a diffraction limited focused spot, all light rays passing through the sub-units of the super-structured lens reach the nano-pillars and the central nano-pillars at the positions (x, y) of the focal point with the phase requirement,

(x=0, y=0) satisfies:

where λ is the wavelength of the spatially incident light and f is the focal length of the subunit.

The spatial light signal 3 is irradiated onto the subunits 111 and 121, and the subunits have a light exit surface 82 and a light entrance surface 81 opposite to the light exit surface 82, and the light entrance surface 81 is curved. Illustratively, the curved surface of the subunit is spherical.

It can be understood that the light incident surfaces (curved surfaces) of the subunits in the micro lens array are connected, after the light beam irradiates the micro lens array, the light beam passes through the micro lens array, a plurality of sub light beams related to the micro lens array can be obtained, the numerical aperture of the lens is matched with the light spot size of the space light information, the light emergent surface faces the direction of the grating array, the light emergent surface is adjusted to be perpendicular to the incident light beam, the incident light beam is ensured to be incident into the effective aperture of the grating coupler, the efficient receiving of the light information is further realized, and the micro lens has the characteristics of small unit size and high integration level.

The chip in the application utilizes the characteristic that the micro lens can regulate and control the wave front, converges the space light, improves photon utilization rate through integrating the grating array and the micro lens array, and realizes high-efficiency coupling between the high-refractive-index optical waveguide transmission line and the free space light beam. The micro-lens array is designed at the front end of the grating array, the optical path accumulation is changed to realize phase shift by modulating the structure and arrangement mode of the micro-lens array, the change of polarization, phase and amplitude of light waves is realized, and the effective filling coefficient is improved, so that the purpose of improving the effective receiving aperture of the grating array is achieved, the electromagnetic regulation and control are realized, the characteristics of light weight and planarization are realized, and the miniaturization and integration of an optical system are facilitated.

On the basis of the above, the application further provides a space light receiving and photoelectric conversion chip of the micro-lens array auxiliary grating array, which aims at the problem that the signal is difficult to realize high-speed parallel output due to low receiving aperture efficiency and adjacent radio frequency channel signal crosstalk in signal detection of the traditional photoelectric detector array.

As shown in fig. 5, the micro lens array-assisted grating array spatial light receiving and photoelectric conversion chip according to an embodiment of the present application specifically includes a micro lens array 1, a grating array 2, a spatial light signal 3, a converging beam 4, a photodetector array 5, an optical waveguide transmission line 6, a radio frequency output interface array 7, and a circuit board 8. The structure, connection and position relation of the three components are the same as those of any one embodiment of the space light receiving chip of the micro lens array auxiliary grating array, wherein the micro lens array 1, the grating array 2 and the optical waveguide transmission line 6 are included; the photoelectric detector array 5 is connected with the output of the grating array 2; the photodetector array 5 is also connected with a circuit board 8 and a radio frequency output interface array 7. The number of the optical waveguide transmission lines 6, the subunits in the micro lens array 1, the grating couplers in the grating array 2, the photodetectors in the photodetector array 5 and the number of the radio frequency output interfaces of the radio frequency output interface array 7 are matched in a one-to-one correspondence manner.

The micro lens array 1 is arranged at the front end of the chip, and the grating array 2 is positioned on the back focal plane of the micro lens array 1 so as to realize efficient coupling between the optical waveguide transmission line and the space light beam.

The photodetector array 5 is connected with the grating array 2 through the optical waveguide transmission line 6, and is used for converting the space optical signal 3 into a microwave signal after acquiring the incident space light received by the micro lens array 1.

The photodetectors in the photodetector array 5 are all connected with the corresponding radio frequency output interfaces in the radio frequency output interface array 7 through the circuit board 8 so as to realize multichannel parallel output.

The optical wave is transmitted to the on-chip photoelectric detector by the optical waveguide transmission line, so that the high-speed conversion from the optical wave to the microwave signal can be realized, and the parallel output of multiple microwave signals is completed; it should be further noted that this process can obtain the information carried by the spatial light and convert it into a microwave signal.

The technical effects of some embodiments of the present application are presented in: the optical fiber is simple to assemble and high in efficiency, free space light beams are received through an integrated photon technology under the condition that design difficulty and cost are not greatly increased, the problem of non-uniformity of space light reception of a grating coupler in an integrated light receiving chip can be solved, the convergence of space light in a certain incidence range can be realized, a compact, low-power-consumption, low-cost, multifunctional and highly-extensible optical signal processing mode is brought for traditional free space optical application, in the application, the improvement of the receiving aperture efficiency of the grating coupler on the basis of the existing grating coupler structure mentioned in the background technology is realized, and the high aperture efficiency focusing and transmission of space light information are realized.

The technical effects of some embodiments of the present application are presented in: the aperture efficiency of the grating coupler is increased, the efficient coupling between the optical waveguide and the free space beam is realized, the optical information loss is reduced, the utilization rate of the beam is improved, and the two-dimensional large-scale, high-receiving aperture efficiency, the preparation of the multi-array element photoelectric conversion array and the high-speed parallel output of the radio frequency signal are realized.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered by the scope of the claims of the present invention.

Claims (10)

1. The space light receiving chip of the micro lens array auxiliary grating array is characterized by comprising

The micro lens array is positioned in the incidence direction of the space light and used for converging the space light;

a grating array on an exit light path of the spatial light through the microlens array, wherein the microlens array comprises a plurality of subunits configured to converge a portion of a beam of the spatial light, one subunit of the microlens array overlying one of the grating couplers in the grating array such that each subunit of the microlens array converges a portion of a beam of spatial light within an effective receiving aperture of its overlying grating coupler.

2. The spatial light receiving chip of claim 1, wherein the microlens array assists the grating array, wherein: and an optical waveguide transmission line which transmits the output of the grating array outwards.

3. The spatial light receiving chip of claim 1, wherein the microlens array assists the grating array, wherein: the subunits are microlenses or super-lenses.

4. A microlens array assisted grating array spatial light receiving chip according to claim 3, wherein: each subunit of the microlens array is arranged in a periodic arrangement, each subunit being configured such that spatial light incident on the microlens array passes through the microlens array and exits along an optical axis of each subunit to an effective aperture of the grating coupler.

5. The spatial light receiving chip of claim 4, wherein the microlens array assists the grating array, further comprising: each subunit has the same focal length and the focal points are on the same side, such that the exit side of the microlens array forms a focal plane that is formed by the focal points of each subunit.

6. The spatial light receiving chip of claim 5, wherein the grating array is disposed on the focal plane of the microlens array, and an effective aperture of a single grating coupler in the grating array corresponds to a size of the beam after converging the sub-units one by one.

7. The microlens array assisted grating array spatial light receiving chip of claim 1, wherein the microlens array and the grating array are configured such that the subunit concentrates the beam of spatial light into the effective receiving aperture of the grating coupler comprising the steps of:

determining a focusing light spot range of the light beam of the space light, which is emitted from each subunit and then enters the surface of the grating coupler;

theoretical calculation is carried out according to the space light range received by the subunit and the space where the position of the focusing light spot is located on the rear surface of the lens

Wherein NA' is a numerical aperture, n is the refractive index of the lens working medium, D is the lens size, f is the focal length of the subunit, and beta is half of the maximum cone angle when light exits the subunit of the microlens array, so that the focal length and the numerical aperture of the subunit are obtained;

determining the position relation between the micro lens array and the grating array according to the position of the focusing light spot on the grating coupler; wherein the position of the focused spot follows the gaussian lens formula:

where u is the distance from the incident beam to the front surface of the subunit of the microlens array, and u= infinity, v is the distance from the rear surface of the subunit to the surface of the grating coupler, and has a value of f, because the incident beam is normal incident space light;

coupling and aligning the micro lens array and the grating array according to the position relation;

wherein the subunit is configured to receive a spatial light beam at a normal incidence.

8. The spatial light receiving chip of claim 7, wherein the existing structure of each grating coupler is tested to obtain a movable receiving range with high coupling efficiency, so as to determine a light spot range of the light beam entering the surface of the grating coupler after exiting the corresponding subunit.

9. The space light receiving and photoelectric conversion chip of the auxiliary grating array of the micro lens array is characterized by further comprising a circuit board, wherein the space light receiving chip of the auxiliary grating array of the micro lens array is arranged on the circuit board; and the photoelectric detector arrays are arranged on the circuit board and are configured to convert the output of one grating coupler in the space light receiving chip of the micro lens array auxiliary grating array, which is transmitted by the optical waveguide transmission line, into a microwave signal by the photoelectric detector in each photoelectric detector array.

10. The micro-lens array assisted grating array space light receiving and photoelectric conversion chip according to claim 9, further comprising a plurality of radio frequency output terminals disposed on the circuit board and configured such that one of the radio frequency output terminals is connected to one of the photodetectors in the photodetector array to output the microwave signal received from the photodetector, and transmit intensity, amplitude and phase information of the space light, so as to realize amplitude-phase detection of the space light.

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