IdealPhotonics all-fiber acousto-optic modulator allows users to change the output light amplitude, duration, and period/frequency. Insertion loss can be as low as 2 dB, extinction ratio can reach up to 50 dB, rise time can be as low as 5 nanoseconds, and periodicity can reach hundreds of MHz. Applications include switching, pulse picking, fast attenuators, etc. The wavelength range spans from near ultraviolet to near infrared. A special application of the modulator is the programmable attenuator. Attenuators are key components in the design of fiber optic transmission systems. They are used to match the optical power level with the dynamic range of the receiver, adjust the input and output levels in EDFA, equalize the power between different DWDM channels, and test the overall system performance under different optical power conditions.