Abstract: A metal-semiconductor-metal photodetector (18) is provided including an optical waveguide (22) disposed on a substrate (28) and an array of metal-semiconductor-metal photodiodes (20) coupled to the optical waveguide (22). An absorber (30) is disposed between the photodiodes (20) and the optical waveguide (22) and a transmission line (26) is coupled to the photodiodes (20). Each of the photodiodes (20) includes an electrode (24) having a plurality of interdigitated electrode fingers (31) wherein a width of each finger (31) and a gap between adjacent fingers (31) tapers from one end of the electrode (24) to the other. Preferably the rate of tapering corresponds to an exponential rate of optical power decay through the photodiode (20). In this way, both the photocurrent density in the fingers (31) and the uniformity of the electric field underneath the electrodes (24) are optimized.