Design and preparation of wavelength gradient film
Based on actual needs, using magnetron sputtering method, on the basis of 50 G narrowband optical film, by using baffle to block, coating different thickness of film on the glass, realize the center wavelength gradient at different physical positions 50 G narrowband optical film.
Optical film is an important part of modern optical devices. It uses the interference effect of light to change the polarization, phase and energy of transmitted or reflected light by coating one or more layers on the surface of various optical materials.
Optical thin film devices are widely used in optical communication networks. With the advent of the information age, the rapid development of the Internet and various information services, especially the development of multimedia services such as video and voice, the demand for bandwidth and capacity of optical fiber communication networks is increasing. The higher the coming, the higher and higher requirements are put forward on the design and technology of optical films.
Narrowband optical film is widely used in optical communication DWDM, as well as detection and monitoring in optical fiber trunk roads. The design and process are relatively mature. However, the current optical thin films are mostly based on uniform coating of the film layer on the substrate, and the optical performance of each part on the entire substrate is almost the same. There are few studies and reports on the simultaneous coating of films with different spectral properties on the same substrate.
With the development of optical communications, more and more information capacity and optical channels are included in the communication trunk. If ordinary optical films are used, one optical film and supporting optical devices are required for each channel, but the wavelength gradient film only needs A set of devices can simultaneously detect up to 40 channels of optical signals in the main road, saving a lot of space and devices.
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The wavelength-graded film means that the center wavelength of the pass band of the film gradually increases from the center to the edge. Based on the ordinary 50 G narrow band, the spatial change of the center wavelength is achieved through the spatial gradation of the film thickness. Generally, a mask with a fixed profile is used. The substrate is close to the mask and rotates relative to the mask. The opening angles of the sputtering source at different radii of the substrate are different, and different average deposition rates are obtained.
This article introduces the design method and optical performance of the wavelength gradient film, using the self-made mask and mask switching device, the process of coating the wavelength gradient film in the magnetron sputtering machine and analyzes the results.
1. The design and optical performance of the wavelength gradient film
According to usage requirements, the wavelength gradient film needs to contain 40 channels, and the spectral performance requirements of each channel are shown in Table 1:
Table 1 Optical performance of each channel of the wavelength gradient film
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Design and preparation of wavelength gradient film
The schematic diagram of the spectral curve is shown in (only a few channels are marked as examples).
Design and preparation of wavelength gradient film
The structure of the wavelength gradient film in the radial direction of the substrate is as shown:
Design and preparation of wavelength gradient film
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In this paper, the two-sided polished glass is coated with a wavelength gradient film on one side and an antireflection film on the other side. The reflectivity of the AR coating is less than -38 dB, because the AR coating process is very mature and is often seen in reports. This article will not elaborate.
This article uses the TFO design software based on Matlab programming and refers to the 50 G narrowband design. It uses glass as the substrate and uses SiO2 and Ta2O5/Nb2O5 as high and low refractive index materials. It is a design example:
Design and preparation of wavelength gradient film
The spectral performance of the film simulated by this design is shown in.
Design and preparation of wavelength gradient film
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5 Conclusion
The optical properties and design methods, coating process and measurement methods of the wavelength gradient film are introduced. Using self-designed mask and mask switching device, the wavelength gradient film is plated in a high vacuum environment. The measurement results show that the wavelength gradient film prepared by this technology meets the design requirements and can meet the market demand.
Founded in 2015,Zunhua Baorui Titanium Equipment Co.,Ltd. is a manufacturer specializing in pvd vacuum ion coating equipment. The company’s products mainly include large plate coating machine, large tube collating machine, tool coating machine and LOW-E glass production line. Mr.Wang baijiang ,general manager of the company ,has been engaged in vacuum coating industry for more than 30 years. He continuously improve production technology, improve product performance and devote himself to provide customers with better product experience and higher production efficiency.