Variable Opticalattenuator Utilizing Hybrid Integrated Sion/polymer Channel Waveguide Platform

Variable Optical Attenuator(VOA), which can reduce the signal energy in the optical communication devices according to the requirement of the user, has been widely used in the test of optical devices and optical communication system, especially in the Dense Wavelength Division Multiplexing(DWDM) optical communication system. VOA not only can accurately control the power of the light signal, provide stability for all communication wavelength attenuation, and realize the channel equalization, but detect the dynamic range of transmission system and compensate power fluctuations in the optical transmission system.VOA based on its production technology can be classified as the traditional mechanical type, LCD type, micro-electro-mechanical system, and planar lightwave circuit. VOA based on planar optical waveguide, which usually be realized by utilizing thermo-optical effect and have the advantages of small volume, stable performance and ease of integration. Planar optical waveguide type VOA can be made of inorganic materials, such as silicon, silicon oxynitride(SiON), and organic polymer material.VOA which made of inorganic materials, such as silicon and SiON, has excellent optical performances, good stability, but large power consumption. Whereas, VOA which made of polymer materials, has the advantages of low power consumption, low cost and so on, but its optical performance and stability are relatively poor, what’s more,it is easy to age. In order to solve above problems, and at the same time, considering SiON material with excellent optical performance and positive thermo-optical coefficient and polymer material with larger negative thermo-optical coefficient and so on, a VOA utilizing hybrid integrated SiON/polymer channel waveguide is proposed.The paper’s main contents and outcome as follows:1.Design and simulation of the parameters of the planar lightwave circuit type VOA.Firstly, study the realization way of planar lightwave circuit type VOA, selected S-shaped curved waveguide structure. Then according to the selected SiON and polymer materials, utilizing effective index method and marcatili method to analyze and design single-mode rectangular waveguide. Further, analyzing the S-bend waveguideloss by the theory of bend waveguide to obtained geometric structure parameters of the device, then using thermal simulation softwave to analyze power consumption of the heater to complete the design of the heater. Finally, utilizing BPM simulation analyze the performance of the overall device. It turns out that for 1550 nm wavelength, VOA achieves the attenuation of 50 dB only need 4.0 mW of power.2.Study of the fabrication processes of the planar optical waveguide type VOA.According to the designed parameters and the selected material property to design the fabrication technological process, and on this basis, the mask used in the fabrication work was custom-made, then the fabrication processes, such as lithography, magnetron sputtering and inductuvely coupled plasma(ICP) etching, were investigated through many experiments so as to optimize the process parameters. Lastly, According to the optimized parameters, the corresponding device was fabricated successfully.3.Test and optimization of planar optical waveguide type VOAFirstly, set up the test platform, then test optical properties, such as single mode features, insertion loss, the minimum insertion loss of 5.4 dB is obtained; Secondly, by the way of changing the environment temperature of the device to test device performance, results show that the device can realize 0~40 dB attenuation range,corresponding the maximum temperature change of 70.4°C; further, by changing the power applied on VOA heater to test device performance, the results show that VOA can obtain attenuation range of 0~50 dB, the maximum power of 328 mW, device implements attenuation of 27 dB, correspondingly, power consumption of 83 mW;Finally, we analyze the causes of measured power consumption larger than that of theoretical results, and introduce the method of reducing power consumption.