Research On Ultra-narrow Bandwidth Tunable Optical Filter

With the great development of data services, the data size of network realized an explosive growth. The demands of data quantity require a higher capacity of channels. DWDM(Dense Wavelength Division Multiplexing) is one of key technologies which expanded data bearing capacity of channels. However, increasingly intensive communication channels put forward higher requests for optical data processing ability of communication devices.High speed and large capacity communication systems have an ultra-narrow channel spacing. Such wavelength allocation mode for optical communication devices has brought two problems to be solved:(1)light signals become more vulnerable to the effects of all kinds of transmission damages;(2) smaller channel spacing requires spectral elements have more narrow filter bandwidth. In order to solve the above two problems, TOF(Tunable Optical Filter) based on double gratings structure appears at the historic moment. This research is to design a kind of ultra-narrow bandwidth tunable optical filter, in improving the processing performance of OCM, further satisfy the bandwidth requirements of new optical network.For researching the ultra-narrow bandwidth tunable optical filters that applied to high-speed optical communication systems. A tunable optical filter by using a structure of double gratings and MEMS mirror was given. Through theoretical analysis and experimental verification, the20dB filter bandwidth achieved a level that less than0.4nm. The experimental results show that the optical filter with double gratings has performance characteristics of high stability and excellent repeatability, which has met the bandwidth demand. This scheme can reduce the filter bandwidth and improve the stability significantly.This paper presents a design of TOF, and analyses and calculations have been done. Then, the actual production sample has been tested. The test results show that the TOF has reached the design requirements, and can work effectively in practical high speed DWDM systems.