CN-224216909-U - Anti-crosstalk multimode interference coupler for MZI structure

Abstract

The invention discloses an anti-crosstalk multimode interference coupler for an MZI structure, which particularly comprises a multimode interference area waveguide of a single-mode input waveguide, two single-mode output waveguides, two stray light interference area waveguides and two metal absorption areas, wherein the metal absorption areas, the stray light interference areas, the stray light output waveguides, the multimode interference area waveguides and the single-mode output waveguides are sequentially connected, and the coupler is axisymmetric by taking the single-mode input waveguides as axes.

Inventors

• TAO SHIQI
• YUAN SHUAI
• SUN HAOCHENG

Assignees

• 武汉安湃光电有限公司

Dates

Publication Date

20260508

Application Date

20250523

Claims (8)

1. 1. An anti-crosstalk multimode interference coupler for an MZI structure is characterized in that the coupler comprises a substrate layer, a single-mode input waveguide, a multimode interference zone waveguide, two single-mode output waveguides, two stray light interference zone waveguides and two metal absorption zones; The metal absorption region, the stray light interference region waveguide, the stray light output waveguide, the multimode interference region waveguide and the single-mode output waveguide are sequentially connected; The single-mode input waveguide, the multimode interference zone waveguide, the single-mode output waveguide, the stray light interference zone waveguide and the metal absorption zone are uniformly distributed on the substrate layer; the coupler is an axisymmetric coupler with a single-mode input waveguide as an axis.
2. 2. The anti-crosstalk multimode interference coupler for MZI structures of claim 1, wherein the input end of said stray light output waveguide is an S-bend waveguide.
3. 3. The anti-crosstalk multimode interference coupler for MZI structures of claim 2, wherein said S-shaped curved waveguide comprises a section of straight waveguide and a section of curved waveguide.
4. 4. The crosstalk-preventing multimode interference coupler of claim 3 wherein the straight waveguides have a length of 5-50 μm and the curved waveguides have a length of 15-20 μm.
5. 5. The anti-crosstalk multimode interference coupler for MZI structures of claim 1, wherein the base layer is, in order from bottom to top, a silicon substrate layer, an oxygen buried layer, a lithium niobate slab layer, a lithium niobate waveguide layer, a metal absorbing layer, and a dielectric film material.
6. 6. The anti-crosstalk multimode interference coupler of claim 5 wherein the metallic material of the metallic absorbing zone comprises gold, titanium, chromium, aluminum, molybdenum, and tungsten.
7. 7. The anti-crosstalk multimode interference coupler of claim 6 wherein the dielectric film material comprises air clad, silica, alumina, silicon oxynitride, SU8 photoresist, and SOG spin-on glass.
8. 8. The anti-crosstalk multimode interference coupler for MZI structures of claim 7, wherein said stray light interference zone waveguide output outputs a spike waveguide arrangement having a length of 2-10 μm.

Description

Anti-crosstalk multimode interference coupler for MZI structure Technical Field The invention relates to the technical field of integrated optical devices, in particular to an anti-crosstalk multimode interference coupler for an MZI structure. Background With the continuous development of emerging technologies such as big data, cloud computing, artificial intelligence, 6G communication and the like, the communication capacity is exponentially increased, and the information processing speed is also increasing. It is expected that high speed, low crosstalk, low noise, high bandwidth, etc. solutions are the main direction of development of future optoelectronic devices. Lithium niobate crystals (LiNbO 3, LN for short) are also called "optical silicon", and are an important integrated semiconductor material in the field of communications. LN is a negative uniaxial birefringent crystal with a wavelength transmission range light having a transparent window in the communication band. Meanwhile, LN also has excellent photorefractive effect, nonlinear effect, electro-optical effect, acousto-optic effect, piezoelectric effect and the like, and the traditional LN body material is widely applied to the fields of modulators, optical fiber sensors, optical fiber gyroscopes and the like, and LN has great development potential as a mature commercial material. In recent years, thin film lithium niobate (TFLN for short) has been the subject of intense research. Due to a series of advantages of high integration, low cost, low power consumption and the like, the development is rapid, and the LN material is expected to replace the traditional LN material in a plurality of application fields in the future. The traditional fiber-optic gyroscope realizes mode polarization and filtering through the body lithium niobate, but the operations such as light splitting and the like cannot be realized on a chip due to the large structural size of the device. For TFLN, multiple functions can be implemented on the chip due to its higher integration. The higher integration level and the thin-film device structure design also bring new problems, such as on-chip polarization effect reduction caused by interference of stray light leaked from the waveguide on other structures. The leakage condition is not serious in waveguide transmission, but in an MMI region, mode mismatch is caused by the change of waveguide width, and coherent extinction of reverse transmission is completely converted into stray light and the like, so that the structure of the MMI needs to be optimized in an application scene with high requirements on polarization degree. Disclosure of Invention The invention aims at the problems, and provides an anti-crosstalk multimode interference coupler for an MZI structure, which provides feasibility for reducing crosstalk introduced by the multimode interference coupler of the MZI structure on TFLN and lays a foundation for the development of large-scale integration of thin film lithium niobate (LNOI for short) on an insulator, and the coupler comprises a basal layer, a single-mode input waveguide, a multimode interference zone waveguide, two single-mode output waveguides, two stray light interference zone waveguides and two metal absorption zones; The metal absorption region, the stray light interference region, the stray light output waveguide, the multimode interference region waveguide and the single-mode output waveguide are sequentially connected; The single-mode input waveguide, the multimode interference zone waveguide, the single-mode output waveguide, the stray light interference zone waveguide and the metal absorption zone are uniformly distributed on the substrate layer; the coupler is an axisymmetric coupler with a single-mode input waveguide as an axis. Optionally, the input end of the stray light output waveguide is an S-shaped curved waveguide. Optionally, the S-shaped curved waveguide includes a straight waveguide and a curved waveguide. Optionally, the length of the straight waveguide is 5-50 μm, and the length of the curved waveguide is 15-20 μm. Optionally, the substrate layer comprises a silicon substrate layer, an oxygen-buried layer, a lithium niobate flat plate layer, a lithium niobate waveguide layer, a metal absorption layer and a dielectric film material from bottom to top. Optionally, the metal material of the metal absorbing region includes gold, titanium, chromium, aluminum, molybdenum, and tungsten. Optionally, the dielectric film material includes air cladding, silicon dioxide, aluminum oxide, silicon oxynitride, SU8 photoresist, and SOG spin-on glass. Optionally, the output end of the stray light interference area waveguide outputs a spike waveguide arrangement with the length of 2-10 μm. Compared with the prior art, the invention has the beneficial effects that: 1. The invention can collect and conduct coherent extinction light through the multimode interference coupling region through the additional w