Optimization and analysis of variable fiber optic attenuator with DMD using ZEMAX

In order to analyze the resolution of variable fiber optic attenuator (VOA) instrument using digital micromirror device (DMD) precisely, the optical system of VOA is optimized and analyzed using Zemax to obtain the effective distributions of incident Gaussian beam (inside 1/e2 Gaussian beam waist region) on the DMD. The beam is then divided into three power attenuation zones P1, P2 and P3 using two cutoff normalized weight levels W1 and W2 for the DMD spatial samplers to arrive the desired high power attenuation resolution. C-Lens is also used as collimator to improve the working distance and decrease the insertion loss. Numerical simulation results indicate that the average power attenuation resolution is 5.072mdB, 3.811mdB and 0.674mdB respectively when the power attenuation percentage is 34.70%, 31.46% and 33.76% for P1, P2 and P3 respectively. The study can be used to VOA test instrument applications.