On-chip integrated nineteen-core five-mode fan-in and fan-out device and orbital angular momentum-based detection system thereof

Abstract

The utility model discloses an on-chip integrated nineteen-core five-mode fan-in and fan-out device and a detection system based on orbital angular momentum, and the device comprises eighteen bent multi-mode waveguides with doughnut-shaped sections and a straight multi-mode waveguide which is located at the center and has the same section, each bent multi-mode waveguide is composed of 24 bent single-mode waveguides, the straight multimode waveguide is composed of 24 straight single-mode waveguides. Through the waveguide configuration of a special structure, after the structured light of each core of the multi-core optical fiber is transmitted in the device, the structured light can be effectively separated in space on the basis of keeping the original OAM mode, so that the processing and analysis of a subsequent light field on a multi-mode signal are facilitated, and a hardware basis is provided for high-capacity optical communication based on orbital angular momentum.

Description

Technical Field

[0001] The utility model relates to a technology in the field of optical waveguides, in particular to an on-chip integrated nineteen-core five-mode fan-in fan-out device and a detection system based on orbital angular momentum. Background Art

[0002] Orbital angular momentum is an emerging degree of freedom in the field of optics, and has extremely high application value in the field of classical optical communications. Long-distance communications based on orbital angular momentum light combined with multi-core optical fiber systems can increase the communication capacity of existing single optical fibers by dozens or even hundreds of times. However, in order to analyze and process the signal light field in each fiber core, it is necessary to use fiber fan-in and fan-out devices to separate each core in space. There are many types of traditional fiber fan-in and fan-out devices, but most of them are limited to single-mode and free-space devices, and cannot meet the fan-in and fan-out requirements of orbital angular momentum in terms of stability, miniaturization, and potential industrial production. Utility Model Content

[0003] The utility model aims at the multiple shortcomings of the prior art, such as the inability to transmit orbital angular momentum light beams, the inability to keep the orbital angular momentum light beam mode unchanged during propagation, the inability to realize multi-core and multi-circle fan-in and fan-out at the same time in three-dimensional space, and the inability to transmit and maintain the information loaded by the orbital angular momentum degree of freedom. The utility model proposes an on-chip integrated 19-core five-mode fan-in and fan-out device and a detection system based on orbital angular momentum. Through a specially constructed waveguide configuration, the structured light of each core of the multi-core optical fiber can be effectively separated in space while maintaining the original OAM mode after being transmitted in the device, which facilitates the subsequent light field processing and analysis of the multi-mode signal, and provides a hardware foundation for high-capacity optical communication based on orbital angular momentum.

[0004] The utility model is realized by the following technical solutions:

[0005] The utility model relates to an on-chip integrated 19-core five-mode fan-in fan-out device, comprising: 18 curved multimode waveguides with donut-shaped cross-sections and a straight multimode waveguide with the same cross-section located in the center, wherein: each curved multimode waveguide is composed of 24 curved single-mode waveguides, and the straight multimode waveguide is composed of 24 straight single-mode waveguides.

[0006] The nineteen multimode waveguides of the fan-in port of the device are respectively distributed at the vertices and the center of two circles of hexagons with side lengths of 50 μm and 100 μm, and the waveguides of the fan-out port are respectively located at depths of 354 μm, 250 μm, and 146 μm, with a spacing of 120 μm.

[0007] The straight multimode waveguide is specifically a multimode waveguide with a donut-shaped cross-section formed by 24 straight single-mode waveguides, specifically: the inner circle radius is 6.9 μm, the outer circle radius is 7.9 μm, a point is taken every 30 degrees on the inner and outer circles, and the points of the inner and outer circles are staggered at equal intervals of 15 degrees; these 24 points are the center points of the 24 single-mode waveguides.

[0008] The curved multimode waveguide comprises: straight waveguide parts located at both ends and a curved waveguide part located in the middle, wherein: the straight waveguide part is a non-curved straight waveguide with a length of 3 mm; the curved waveguide part is a curved waveguide that changes simultaneously in the horizontal and vertical directions based on the cosine function form;

[0009] The curved multimode waveguide group and the straight multimode waveguide are processed by, but not limited to, femtosecond laser direct writing technology, specifically: 2cm×2cm borosilicate glass material is cut out, and the surface is wiped with alcohol to ensure that there is no dust on the surface; a 513nm femtosecond pulse laser with a single pulse energy of 2.7uJ is focused at a depth range of 146μm-354μm below the glass surface, the material is modified within the depth range at a speed of 5mm / s, and 24×18 curved single-mode waveguides and 24 straight single-mode waveguides in a donut shape are directly written.

[0010] The utility model relates to an orbital angular momentum detection system based on the nineteen-core five-mode fan-in fan-out device on the above-mentioned photonic integrated chip, comprising: a laser light source, an orbital angular momentum generation module, a photonic integrated chip arranged on a four-dimensional translation stage, an orbital angular momentum test module, a coupler and a power meter arranged in sequence.

[0011] Technical Effects

[0012] The utility model uses a donut-shaped structure to ensure low-loss and low-crosstalk transmission of the orbital angular momentum beam in the device, and combines a specially constructed curved waveguide configuration to ensure effective fan-in and fan-out of the orbital angular momentum beam in the device; the donut-shaped waveguide is embedded in the photonic integrated chip through femtosecond laser direct writing. Compared with the prior art, the ability to simultaneously transmit multiple orbital angular momentum on the chip is increased, and this control capability is combined with the existing multi-core fan-in and fan-out technology, providing a new idea for multiplexing and demultiplexing modules in multi-mode large-capacity optical fiber communication systems. In addition, it can also be used for short-distance large-capacity communications such as data centers, and can realize multiplexing and demultiplexing in multi-core multi-mode communication systems on the chip. Its stability, miniaturization and mass production potential far exceed traditional methods, and the number of communication channels is increased to 19×3=57. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the utility model;

[0014] In the figure: (a) is a microscope image of the cross section of a seven-core fan-in port; (b) is a microscope image of a single-core fan-out port;

[0015] Figure 2 Schematic diagram of waveguide arrangement;

[0016] In the figure: (a) is the input end and (b) is the output end. 1-19 are 19 multimode waveguides respectively. 1 is a straight multimode waveguide and 2-19 are curved multimode waveguides. The waveguide position 1 at the input end of Figure (a) changes to the corresponding position 1 at the output end of Figure (b), and the position 2 in (a) changes to the position 2 in (b), and so on.

[0017] Figure 3 This is a femtosecond laser processing design structure diagram of the utility model (19-core orbital angular momentum multiplexing fan-in fan-out device);

[0018] In the figure: (a) is a schematic diagram of the overall 19-core device design structure, where 101 is a straight waveguide part and 102 is a curved waveguide part; (b) Figure 2 Single curved multimode waveguide Figure 3 Taking as an example, the designed bending structure is explained. (b), (c), and (d) show the yoz, xoy, and xoz cross-sectional views of the bent multimode waveguide, respectively. The length change in the x direction of the main image in (c) and (d) is much greater than the length change in the y and z directions, so the illustrations are used to show the screenshots after adjusting the three-dimensional angle and scaling the bending part.

[0019] Figure 4 Schematic diagram of 24 single-mode waveguides forming a donut structure to form an orbital angular momentum waveguide. The blue dots are the arrangement of the 24 single-mode waveguides.

[0020] Figure 5 It is a schematic diagram of an embodiment application. DETAILED DESCRIPTION

[0021] like Figure 3 As shown, an on-chip integrated 19-core five-mode fan-in and fan-out device involved in this embodiment includes: 18 curved multimode waveguides with donut-shaped cross-sections and a straight multimode waveguide with the same cross-section located in the center, wherein: each curved multimode waveguide is composed of 24 curved single-mode waveguides, and the straight multimode waveguide is composed of 24 straight single-mode waveguides.

[0022] like Figure 4As shown, the fan-in port of the device has five layers with a layer spacing of 43.3μm; the output end has three layers with a layer spacing of 104μm; six of the seven wires in the first and second layers of the input end, namely, numbers 3, 4, 10, 11, 12, and 13 in the figure, are mapped to the first layer of the output end, one edge wire in the second and fourth layers and five wires in the third layer, namely, numbers 1, 2, 5, 8, 9, 14, and 15 in the figure, are mapped to the second layer of the output end, and the rest are mapped to the third layer. This structure can minimize the lateral and longitudinal bending of the waveguide.

[0023] like Figure 5 As shown, this embodiment relates to an orbital angular momentum detection system based on the nineteen-core five-mode fan-in and fan-out device on the above-mentioned photonic integrated chip, including: a laser light source, an orbital angular momentum generation module, a photonic integrated chip arranged on a four-dimensional translation stage, an orbital angular momentum test module, a coupler and a power meter arranged in sequence, wherein: the orbital angular momentum generation module simulates the multi-mode optical fiber emission, the orbital angular momentum test module detects various properties of the chip emission light beam, the laser light source couples the structured light field into the photonic integrated chip and tests the power and purity distribution of the waveguide output light spot through the power meter.

[0024] The photonic integrated chip has a donut-shaped waveguide embedded therein by femtosecond laser direct writing.

[0025] This embodiment involves the working process of the above detection system, including:

[0026] Step a) using a 1550nm continuous laser as a light source, outputting a Gaussian beam output by a single-mode optical fiber to an SLM loaded with a specific kinoform pattern to prepare a structured light field, and coupling the beam into the chip end face;

[0027] Step b) outputting the output light spot to the spatial light modulator, loading phase diagrams of different orders, collecting the light beam passing through the spatial light modulator with a single-mode optical fiber, and measuring the output power of the single-mode optical fiber;

[0028] Step c) screens out the combination with smaller crosstalk and loss, including: determining that the main energy distribution of the output light spot is in a waveguide of a certain order, recording the power collected by the single-mode optical fiber loaded with different phase information patterns, and obtaining the purity spectrum; according to the purity spectrum, the crosstalk between modes can be calculated, the waveguide with smaller crosstalk and loss can be found, and the direct writing parameters and transmission loss can be recorded.

[0029] After specific actual experiments, in the 1550nm band, the test environment temperature should be within the range of 20℃±5℃; the relative humidity of the test environment should not be greater than 70%. The number of mode channels supported by the 19-core three-mode OAM multiplexing and demultiplexing device was tested using an infrared camera and a power meter, and the average device loss was less than 3dB and the average mode crosstalk was less than -10dB.

[0030] Compared with the existing technology, the utility model uses femtosecond laser direct writing and embeds the fan-in and fan-out array structure of complex orbital angular momentum multiplexing with a depth variation of more than 200mm into the photonic integrated chip through innovative depth control compensation means. Based on the waveguide structure, the multi-mode light of each core of the multi-core optical fiber is effectively separated in space while maintaining the original OAM mode after being transmitted in the device.

[0031] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principle and purpose of the utility model. The protection scope of the utility model shall be based on the claims and shall not be limited by the above-mentioned specific implementation. Each implementation scheme within its scope shall be subject to the constraints of the utility model.

Claims

1. An on-chip integrated 19-core five-mode fan-in fan-out device, characterized in that: include: Eighteen curved multimode waveguides with donut-shaped cross-sections and a centrally located straight multimode waveguide with the same cross-section, wherein: each curved multimode waveguide is composed of 24 curved single-mode waveguides, and the straight multimode waveguide is composed of 24 straight single-mode waveguides; The nineteen multimode waveguides of the fan-in port of the device are respectively distributed at the vertices and the center of two circles of hexagons with side lengths of 50μm and 100μm, and the waveguides of the single-core fan-out port are respectively located at depths of 354μm, 250μm, and 146μm, with a spacing of 120μm.

2. The on-chip integrated nineteen-core five-mode fan-in fan-out device according to claim 1 is characterized in that: The straight multimode waveguide is specifically a multimode waveguide with a donut-shaped cross-section formed by 24 straight single-mode waveguides, specifically: the inner circle radius is 6.9 μm, the outer circle radius is 7.9 μm, a point is taken every 30 degrees on the inner and outer circles, and the points of the inner and outer circles are staggered at equal intervals of 15 degrees; these 24 points are the center points of the 24 single-mode waveguides.

3. The on-chip integrated nineteen-core five-mode fan-in fan-out device according to claim 1 is characterized in that: The curved multimode waveguide comprises: straight waveguide parts at both ends and a curved waveguide part in the middle, wherein: the straight waveguide part is a non-curved straight waveguide with a length of 3 mm; the curved waveguide part is a curved waveguide that changes simultaneously in the horizontal and vertical directions based on the cosine function form.

4. The on-chip integrated nineteen-core five-mode fan-in fan-out device according to claim 1 is characterized in that: The curved multimode waveguide group and the straight multimode waveguide are processed by femtosecond laser direct writing technology, specifically: 2cm×2cm borosilicate glass material is cut out, and the surface is wiped with alcohol to ensure that there is no dust on the surface; a 513nm femtosecond pulse laser with a single pulse energy of 2.7uJ is focused on a depth range of 146μm-354μm below the glass surface, and the material is modified within the depth range at a speed of 5mm / s, and 24×18 curved single-mode waveguides and 24 straight single-mode waveguides in a donut shape are directly written.

5. An orbital angular momentum detection system based on the nineteen-core five-mode fan-in fan-out device on the photonic integrated chip according to any one of claims 1 to 4, characterized in that: include: A laser light source, an orbital angular momentum generation module, a photon integrated chip arranged on a four-dimensional translation stage, an orbital angular momentum test module, a coupler and a power meter are arranged in sequence, wherein: the orbital angular momentum generation module simulates multi-mode optical fiber emission, the orbital angular momentum test module detects various properties of the chip emission light beam, the laser light source couples the structured light field into the photon integrated chip and tests the power and purity distribution of the waveguide output light spot through the power meter.

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