CN107634801A - Transverse SAM and OAM tunable photon emitting/receiving chip and its preparation method - Google Patents

Abstract

The invention relates to a photon emitting/receiving chip with adjustable lateral SAM and OAM, comprising a silicon nitride microring waveguide integrated on the chip, and silicon nitride tapered couplings arranged on both sides of the silicon nitride microring waveguide integrated on the chip In the waveguide structure, the evanescent wave region inside the silicon nitride microring waveguide is provided with an angular grating array.

Description

Transverse SAM and OAM tunable photon emitting/receiving chip and its preparation method

technical field

The invention relates to the field of optical communication or quantum information processing, and more specifically, to a photon emitting/receiving chip with adjustable lateral SAM and OAM and a preparation method thereof.

Background technique

Light carries intrinsic spin angular momentum and orbital angular momentum, which are determined by the polarization and spatial degrees of freedom of the light, respectively. Due to its infinite number of eigenmodes, photon orbital angular momentum (OAM) can theoretically expand the information capacity infinitely. Therefore, photon orbital angular momentum is being widely used in applications such as optical communication and quantum information processing. Photon spin angular momentum is also widely used in quantum entanglement and polarization multiplexing of light. In fact, the spin angular momentum and orbital angular momentum interactions (SOI) of photons are found in inhomogeneous media, optical refraction/reflection interfaces, and explained by modern optical theory. The SOI phenomenon has great potential for new applications, such as optical micro-manipulation, ultra-high resolution imaging, beam shaping, beam splitting, etc.

On the other hand, the photon spin angular momentum SAM is divided into transverse spin angular momentum and longitudinal spin angular momentum according to the relationship between its rotation axis and the beam propagation direction (perpendicular or parallel). Compared with the longitudinal spin angular momentum ubiquitous in nature, the transverse spin angular momentum mainly occurs in inhomogeneous optical fields, such as surface plasmons, evanescent wave regions of waveguide/non-waveguide modes, and strongly focused beams. Light fields carrying transverse spin angular momentum have many new applications in nanophotonics and biosensing. In particular, the transverse spin angular momentum in the evanescent wave induces a strong SOI phenomenon at the boundary of the waveguide mode, or known as the quantum spin Hall effect of light. And cause lateral spin-directional coupling on the interface of light, that is, break the directionality of the excitation mode participated by the evanescent wave on the interface. This characteristic of transverse spin angular momentum has developed a lot of functional devices in applications such as optical diodes, chiral spin-optical networks, and quantum information processing.

Therefore, simultaneously manipulating the lateral spin angular momentum and orbital angular momentum of photons will open up more diverse application prospects in the entire angular momentum domain. And it will bring new functional devices, such as photon state encoding/decoding in SAM-OAM space.

Contents of the invention

The invention provides a photon emitting/receiving chip with adjustable lateral SAM and OAM. The chip can adjust the lateral spin angular momentum and orbital angular momentum of the photon, so it has very broad application prospects.

For realizing above-mentioned purpose of the invention, the technical scheme that adopts is:

A photon emitting/receiving chip with adjustable lateral SAM and OAM, including an on-chip silicon nitride microring waveguide, and an on-chip silicon nitride tapered coupling waveguide structure arranged on one side of the silicon nitride microring waveguide, said The evanescent wave region inside the silicon nitride microring waveguide is provided with an angular grating array.

In the above scheme, when the chip is used as the emitter, the refractive index characteristics of the silicon nitride microring waveguide make the intensity of the radial component and the intensity of the angular component of the light field in the evanescent wave region of the waveguide comparable, generating transverse spin angular momentum, Therefore, by changing the size of the silicon nitride microring waveguide, the magnitudes of the two electric field components in the evanescent wave region of the waveguide can be adjusted, thereby achieving the purpose of adjusting the lateral spin angular momentum. The silicon nitride microring waveguide is used to select the wavelength of the emission spectrum and the topological charge regulation of the orbital angular momentum, and then achieve the purpose of regulating the orbital angular momentum, and then make the silicon nitride microring waveguide through the angular grating array in the evanescent wave region Modes in the waveguide are launched vertically into free space, carrying both lateral spin angular momentum and orbital angular momentum.

When the chip is used as a receiver, only the incident light beams whose wavelength satisfies the resonance condition of the silicon nitride microring waveguide and carry the corresponding OAM order can be coupled into the silicon nitride microring waveguide, and pass through the unidirectional spin angular momentum Coupling characteristics, the light beams carrying left-handed/right-handed SAMs are output to the left/right opposite directions of the silicon nitride tapered coupling waveguide structure, and the selective reception of the two spaces of OAM-SAM is realized.

Simultaneously, the present invention also provides more than a kind of preparation method of chip, and its specific content is as follows:

A method for preparing more than one transmitting/receiving chip, comprising the following steps:

S1. growing a silicon oxide layer on a crystalline silicon substrate, and then depositing a silicon nitride layer on the silicon oxide layer by a chemical vapor phase method;

S2. Spin-coat photoresist, exposure, thermal reflow, and plasma etching steps on the silicon nitride layer to prepare silicon nitride microring waveguides, silicon nitride tapered coupling waveguide structures, and angular grating arrays.

Compared with prior art, the beneficial effect of the present invention is:

The invention combines the advantages of silicon-based integrated photon orbital angular momentum emitting devices and the in-depth study of lateral spin angular momentum in the evanescent wave region, and provides a photon emission/ Receive chip. In this scheme, the silicon nitride microring waveguide is designed to have a large range of adjustable lateral spin angular momentum, while the orbital angular momentum changes the topological charge by changing the input wavelength, which is determined by the excitation direction of the input light. Directions of spin angular momentum and orbital angular momentum emitted into free space. The three conditions work together, and finally the device produces a beam capable of simultaneously carrying tunable lateral spin and orbital angular momentum. When used as a receiving device, the OAM beam incident on the device is selectively coupled to two different directions through the transverse spin of the evanescent wave, realizing the simultaneous selective coupling of OAM-SAM. The design has the advantages of high coupling selection ratio and high purity of the generated SAM-OAM, and adopts the processing technology in the present invention, and the chip can be produced on a general semiconductor microprocessing platform in a large scale, and has great application prospects.

Description of drawings

Figure 1 is a schematic diagram of the structure of the chip.

Figure 2 (a), (b), (c) is the flow chart of chip preparation.

detailed description

The accompanying drawings are for illustrative purposes only and cannot be construed as limiting the patent;

The present invention will be further elaborated below in conjunction with the accompanying drawings and embodiments.

Example 1

As shown in Figure 1, the photon emitting/receiving chip with adjustable lateral spin angular momentum and orbital angular momentum provided by the present invention includes an on-chip silicon nitride microring waveguide 1, and an on-chip integrated silicon nitride microring waveguide 1 The silicon nitride tapered coupling waveguide structure 3 on one side of the waveguide 1 is provided with an angular grating array 2 in the evanescent wave region inside the silicon nitride microring waveguide 1 .

In the above scheme, when the chip is used as the emitter, the refractive index characteristics of the silicon nitride microring waveguide 1 make the intensity of the radial component and the intensity of the angular component of the light field in the evanescent wave region of the waveguide comparable, generating transverse spin angular momentum , so by changing the size of the silicon nitride microring waveguide 1, the magnitude of the two electric field components in the evanescent wave region of the waveguide can be regulated, thereby achieving the purpose of regulating the lateral spin angular momentum. The silicon nitride microring waveguide 1 is used to select the wavelength of the emission spectrum and the topological charge regulation of the orbital angular momentum, and then achieve the purpose of regulating the orbital angular momentum, and then through the angular grating array 2 in the evanescent wave region, the silicon nitride The modes in the microring waveguide 1 are launched vertically into free space and carry transverse spin angular momentum and orbital angular momentum.

When the chip is used as a receiver, only incident light beams with a wavelength that satisfies the resonance condition of the silicon nitride microring waveguide 1 and carries the corresponding OAM order can be coupled into the silicon nitride microring waveguide 1 and passed through the lateral spin angular momentum The one-way coupling feature outputs the light beams respectively carrying two kinds of left-handed and right-handed SAMs to the left/right two opposite directions of the silicon nitride tapered coupling waveguide structure 3, so as to realize the selective reception of the two spaces of OAM-SAM.

In a specific implementation process, the refractive index of the silicon nitride microring waveguide 1 and the silicon nitride tapered coupling waveguide structure 3 is 2.0. The installation height of the silicon nitride microring waveguide 1 and the silicon nitride tapered coupling waveguide structure 3 is 0.6 microns, and the width range of the silicon nitride microring waveguide 1 is 0.8-1.6 microns. The radius of the silicon nitride microring waveguide 1 is 80 microns, the coupling interval with the silicon nitride tapered coupling waveguide structure is 200 nanometers, and the height and width of the outer SU8 waveguide are 3.5 microns.

In the above solution, the angular grating array 2 includes 517 periodically arranged angular gratings. The height and width of the angular grating are both 100 nanometers.

In a specific implementation process, the silicon nitride tapered coupling waveguide structure 3 includes a straight waveguide 31 and a tapered waveguide 32 connected to the straight waveguide arranged at both ends of the straight waveguide 31. The width of the tapered waveguide 32 is 140 The length of the tapered waveguide 32 is 350 micrometers. The outer layer of the tapered waveguide 32 is provided with a SU8 straight waveguide 03, the height of the SU8 straight waveguide 03 is 3.5 microns, and the width is 3.5 microns.

Example 2

This embodiment provides a method for preparing the chip of Embodiment 1, as shown in Figure 2 (a), (b) and (c), the specific scheme is as follows:

S1. A 5-micron-thick silicon oxide layer 01 is grown on a 400-micron-thick crystalline silicon substrate 02, and then a 600-nm-thick silicon nitride layer 00 is deposited on the silicon oxide layer 01 by a chemical vapor phase method;

S2. Spin-coat photoresist, exposure, thermal reflow, and plasma etching steps on the silicon nitride layer 00 to prepare silicon nitride microring waveguides 1, straight waveguides 31, tapered waveguides 32, and angular grating arrays 2 .

S3. Obtain the SU8 straight waveguide structure 03 on the outer layer of the tapered waveguide 32 by overlaying and pattern transfer;

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (9)

1. horizontal SAM and the adjustable photon transmitting/reception chips of OAM, it is characterised in that：Including the silicon nitride micro-loop integrated on piece The silicon nitride taper Coupled Passive Waveguide Structure for being arranged on silicon nitride micro-loop waveguide side integrated in waveguide, and piece, the silicon nitride Evanescent wave area on the inside of micro-loop waveguide is provided with angular grating array.

2. horizontal SAM according to claim 1 and the adjustable photon transmitting/reception chips of OAM, it is characterised in that：It is described The waveguide of silicon nitride micro-loop, the refractive index of silicon nitride taper Coupled Passive Waveguide Structure are 2.0.

3. horizontal SAM according to claim 1 and the adjustable photon transmitting/reception chips of OAM, it is characterised in that：It is described The waveguide of silicon nitride micro-loop, the setting of silicon nitride taper Coupled Passive Waveguide Structure are highly 0.6 micron, the width of silicon nitride micro-loop waveguide Scope is 0.8-1.6 microns.

4. horizontal SAM according to claim 1 and the adjustable photon transmitting/reception chips of OAM, it is characterised in that：It is described The radius of silicon nitride micro-loop waveguide is 80 microns, and the coupling with silicon nitride taper Coupled Passive Waveguide Structure is at intervals of 200 nanometers.

5. horizontal SAM according to claim 1 and the adjustable photon transmitting/reception chips of OAM, it is characterised in that：It is described Angular grating array includes the angular grating of several periodic arrangements.

6. horizontal SAM according to claim 5 and the adjustable photon transmitting/reception chips of OAM, it is characterised in that：It is described The height and width of angular grating are 100 nanometers.

7. horizontal SAM according to claim 1 and the adjustable photon transmitting/reception chips of OAM, it is characterised in that：It is described Silicon nitride taper Coupled Passive Waveguide Structure includes straight wave guide and is arranged on the tapered transmission line being connected with straight wave guide at straight wave guide both ends, cone The width that shape waveguide is carefully located is 140 nanometers, and the length of tapered transmission line is 350 microns.

8. horizontal SAM according to claim 7 and the adjustable photon transmitting/reception chips of OAM, it is characterised in that：It is described The outer layer of tapered transmission line is provided with SU8 straight wave guides, and the height of SU8 straight wave guides is 3.5 microns, and width is 3.5 microns.

A kind of 9. preparation method according to any one of the claim 1 ~ 8 transmitting/reception chip, it is characterised in that：Including with Lower step：

S1. the growing silicon oxide layer on crystal orientation silicon substrate, then by chemical vapor process on silicon oxide layer deposited silicon nitride Layer；

S2. spin coating photoresist, exposure, heat backflow, plasma etch step are carried out on silicon nitride layer, prepares silicon nitride micro-loop Waveguide, silicon nitride taper Coupled Passive Waveguide Structure and angular grating array.