A tilting mirror MEMS variable optical attenuator attenuates light over a band of wavelengths with minimum wavelength dependent loss. The attenuator includes a lens that has a wedged input face and is made from a material that has high dispersion. The lens design causes different wavelengths to travel different paths through the attenuator such that wavelength dependent loss is reduced. The attenuator may be designed to have minimum wavelength dependent loss at a specified attenuation greater than zero.