阅读说明：本技术 一种低损耗红外高非线性光波导制备方法 (Preparation method of low-loss infrared high-nonlinearity optical waveguide ) 是由 张斌 曾平羊 李朝晖 夏迪 杨泽林 宋景翠 朱莺 于 2019-10-22 设计创作，主要内容包括：本发明涉及片上波导的微纳加工领域,特别是一种低损耗红外高非线性光波导制备方法。包括以下步骤：S1.分析硫系光波导在红外波段光波的传输特性；S2.分析电子束曝光各个参数及电子束胶种类对硫系波导制备的影响,选择合适的曝光参数及电子束胶种类进行掩膜版制备,并通过等离子体反应刻蚀,实现波导的制备；S3.其次,通过旋涂法实现聚合物包层的生长；S4.最终,结合包层热退火工艺重新对波导侧壁进行光滑化,并通过截断法进行损耗测试。本发明通过优化电子束曝光及调整等离子体反应的刻蚀参数,并结合热退火工艺,实现一种超低损耗的片上硫系波导制备,适合大规模的高非线性光子集成器件制备。(The invention relates to the field of micro-nano processing of on-chip waveguides, in particular to a preparation method of a low-loss infrared high-nonlinearity optical waveguide. The method comprises the following steps: s1, analyzing the transmission characteristics of the chalcogenide optical waveguide in the infrared wave band; s2, analyzing the influence of each parameter of electron beam exposure and the type of electron beam glue on the preparation of the chalcogenide waveguide, selecting proper exposure parameters and the type of electron beam glue to prepare a mask, and realizing the preparation of the waveguide through plasma reaction etching; s3, secondly, realizing the growth of a polymer cladding by a spin-coating method; and S4, finally, smoothing the side wall of the waveguide again by combining a cladding thermal annealing process, and performing loss test by a truncation method. According to the invention, the preparation of the on-chip chalcogenide waveguide with ultralow loss is realized by optimizing the electron beam exposure and adjusting the etching parameters of the plasma reaction and combining the thermal annealing process, and the preparation method is suitable for preparing large-scale high-nonlinearity photonic integrated devices.)

1. A preparation method of a low-loss infrared high-nonlinearity optical waveguide is characterized by comprising the following steps:

s1, analyzing the transmission characteristics of the chalcogenide optical waveguide in the infrared wave band;

s2, analyzing the influence of each parameter of electron beam exposure and the type of electron beam glue on the preparation of the chalcogenide waveguide, and realizing the preparation of the waveguide through plasma reaction etching;

s3, realizing the growth of a polymer cladding by a spin-coating method;

and S4, combining a cladding thermal annealing process, placing the waveguide device in an annealing furnace, heating to a temperature exceeding the glass transition temperature of the chalcogenide material so as to enable the waveguide to be in a molten state, enabling the side wall of the waveguide to be relatively smooth under the action of surface tension, and carrying out loss test by a truncation method.

2. The method according to claim 1, wherein the cross-sectional structure of the waveguide is ridge-shaped or rectangular, and the selected material is chalcogenide material.

3. The method of claim 2, wherein the selected waveguide structure has a cross-sectional width in the range of 1 micron to 10 microns and a height in the range of 300 nm to 5 microns if the structure is a rectangular waveguide, and a ridge height according to the transmission band requirement if the structure is a ridge waveguide.

4. The method of claim 2, wherein the waveguide structure comprises a lower cladding, a core, and an upper cladding; the refractive index of the fiber core is higher than that of the upper and lower cladding layers, and the contact interface between the fiber core and the cladding layers is smooth.

5. The method according to claim 1, wherein the low-loss infrared high-nonlinearity optical waveguide is prepared by adjusting plasma reactive etching parameters, and the etching process comprises chemical etching and physical etching; CHF is mainly used for chemical etching₃Or CF₄+H₂A gas; physical etching is achieved by Ar or He gas.

6. The method of any one of claims 1 to 5, wherein the waveguide is heated in an annealing furnace at 200 ℃ to 240 ℃ for 8 to 12 hours, depending on the specific material, in combination with a thermal annealing process of the cladding layer by spin coating, i.e. spin coating with a spin coater at a rotation speed of 2000rpm for 1 minute.

Technical Field

The invention relates to the field of micro-nano processing and nonlinear optics, in particular to a preparation method of a low-loss infrared high-nonlinearity optical waveguide.

Background

The infrared wave band comprises a near wave band, a middle wave band and a far infrared wave band, wherein the near infrared wave band comprises a communication wave band, and the middle and far infrared wave bands comprise fingerprint regions of a plurality of biological molecules, typical toxic gases and dangerous goods molecules and an atmospheric greenhouse gas fluorescence spectrum wave band, so that the infrared waveguide with high integration has extremely important research significance. In addition, infrared waveguides also have important application backgrounds in the fields of laser transmission, thermal pixel transmission, infrared spectrum research and the like.

At present, the on-chip infrared waveguide mainly uses germanium, silicon, sulfur and other materials: the germanium waveguide has large loss in the infrared waveguide, and the transmission waveband is mainly 3 mu m later, the germanium waveguide does not contain a communication waveband, while the silicon waveguide has the problems of serious two-photon absorption, large loss, transmission waveband limitation, preparation difficulty and the like.

The chalcogenide waveguide is an amorphous material formed by covalent bonds of sulfur, selenium, tellurium and other metals and non-metallic materials, has the advantages of very wide transmission waveband (from a visible light waveband to 20 mu m), high nonlinearity, extremely low two-photon absorption and the like, and is easy to prepare a thin film by methods such as thermal evaporation, magnetron sputtering and the like and process the thin film into the waveguide; however, the chalcogenide waveguide also has the problems of large loss and the like at present, and the application performance of the chalcogenide waveguide is severely limited. The main reason is that the sidewall of the chalcogenide waveguide has very large scattering due to the rough sidewall caused by the non-uniform etching rate in the chalcogenide waveguide processing process, so that the chalcogenide waveguide has large loss.

Disclosure of Invention

The invention provides a preparation method of a low-loss infrared high-nonlinearity optical waveguide, aiming at overcoming the defects in the prior art.

In order to solve the technical problems, the invention adopts the technical scheme that: a preparation method of a low-loss infrared high-nonlinearity optical waveguide comprises the following steps:

s1, analyzing the transmission characteristics of the chalcogenide optical waveguide in the infrared wave band;

s2, analyzing the influence of each parameter of electron beam exposure and the type of electron beam glue on the preparation of the chalcogenide waveguide, and realizing the preparation of the waveguide through plasma reaction etching;

s3, realizing the growth of a polymer cladding by a spin-coating method;

and S4, combining a cladding thermal annealing process, placing the waveguide device in an annealing furnace, heating to a temperature exceeding the glass transition temperature of the chalcogenide material so as to enable the waveguide to be in a molten state, enabling the side wall of the waveguide to be relatively smooth under the action of surface tension, and carrying out loss test by a truncation method.

Preferably, the cross-sectional structure of the waveguide is a ridge or a rectangle, and the selected material is a chalcogenide material.

Preferably, in the selected waveguide structure, if the structure is a rectangular waveguide, the cross-sectional width ranges from 1 micron to 10 microns, and the height ranges from 300 nm to 5 microns, and if the structure is a ridge waveguide, the ridge height is designed according to the transmission band requirement.

Preferably, the waveguide structure comprises a lower cladding, a core, and an upper cladding; the refractive index of the fiber core is higher than that of the upper and lower cladding layers, and the contact interface between the fiber core and the cladding layers is smooth.

Preferably, the preparation of the low-loss infrared chalcogenide optical waveguide is realized by adjusting plasma reaction etching parameters, and the etching process comprises chemical etching and physical etching; the chemical etching mainly uses CHF3 or CF4+ H2 gas; physical etching is achieved by Ar or He gas.

Preferably, the cladding of the low-loss infrared chalcogenide waveguide is rotated for 1 minute by a spin coater at a rotating speed of 2000rpm by the spin coater to grow a polymer cladding above the waveguide, and the waveguide device is placed in an annealing furnace in combination with a cladding thermal annealing process and heated for 8-12 hours at a temperature of 200-240 ℃ depending on the specific material.

Preferably, the truncation test requires the inclusion of at least two waveguide structures of different lengths. Ensuring that the effects of end-face coupling and coupling errors are eliminated.

Preferably, the waveguide structure is capable of measuring the transmission power, loss factor and operating frequency of the waveguide transmission.

Compared with the prior art, the beneficial effects are: the invention realizes the preparation of the high-nonlinear waveguide with high precision and low side wall roughness by electron beam exposure and adjustment of etching parameters of plasma reaction and combination of a thermal annealing process, and provides a preparation method of the low-loss infrared chalcogenide waveguide compared with the traditional photoetching, thereby realizing the low-loss transmission of infrared waveband light waves.

Drawings

FIG. 1 is a cross-sectional view of a waveguide of the present invention.

FIG. 2 is a SEM representation of a ridge waveguide of the present invention.

FIG. 3 is a simulated electric field pattern of the ridge waveguide of the present invention.

FIG. 4 is a flow chart of the preparation of the present invention.

FIG. 5 is a schematic diagram of a test system according to the present invention.

Detailed Description

The drawings are for illustration purposes only and are not to be construed as limiting the invention; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the invention.