Research On Diffraction Properties Of DMD And Its Applications

With the development of Opto-very-large-scale integration (Opto-VLSI) processors technology, like Micro Electro-Mechanical Systems (MEMS) processor and Liquid Crystal on Silicon (LCoS) etc. Opto-VLSI-based intelligent optical signal processing technique has become a hot issue in recent years and can be potentially applied in optical communication and biomedical imaging.Reconfigurable optical add-drop multiplexer (ROADM) as a key equipment in the future intelligent optical network can be remotely controlled by software. ROADM based on wavelength blocker (WB) has the advantages in low insertion loss, high extinction ratio, more port counts, flexible channel spacing, low cost and high reliability.Digital micromirror device (DMD), a kind of micro-mirror array which is manufactured by Large Scale Integration technique has a broad development and application prospect in the area of image display and optical signal processing. In this paper, a novel wavelength blocking element based on DMD is proposed and experimentally demonstrated. We study the optical diffraction characteristics of DMD according to the grating theory and further solve critical technical problems in the wavelength blocking system. The main content is as follow,(1) According to the photoelectric characteristic of DMD and the scalar diffraction theory, we establish the 2D grating physical model of DMD. Then we analyze the dependence of the diffraction efficiency on the light intensity, the incident angle of light and the pixel pitch of DMD with 13.68μm,10.8μm and 7.6μm respectively at the blazing condition.(2) Based on the theoretical analysis and experimental demonstration, DMD with pixel pitch 13.68μm at incident angle 27.4° is proved to be the best matching the nearly blaze constraint condition in experiment. The light intensity of this DMD is higher than that of the others and diffraction coupling efficiency is the highest.(3) According to the conclusions from the experiment, we further apply DMD with 13.68μm into WB. We estabish a WB system which can block any wavelength channel in C-band. The insertion loss of the system is 5-6dB. It can provide theoretical basis and key technique for the next study of high performance optical filter and high-port-count NxN wavelength blocker based on DMD.