An acousto-optic modulator enhanced by a sub-wavelength acoustic waveguide is provided. The acousto-optic modulator comprising: a substrate, wherein the substrate includes a sapphire underlayment and a silicon dioxide layer disposed on the sapphire underlayment; the substrate further including a lithium niobate thin film, wherein the lithium niobate thin film includes a transducer region and a tapered transition region that are etched, the sub-wavelength acoustic waveguide, an acoustic-photonic crystal cavity, and a side-coupled photonic crystal; wherein the etched transducer region is provided with an interdigital transducer, the sub-wavelength acoustic waveguide is connected with the etched transducer region via the tapered transition region that is etched, the acoustic-photonic crystal cavity is connected with a non-suspended sub-wavelength acoustic waveguide and is arranged parallel to a suspended side-coupled photonic crystal.

Systems and methods for temporal amplitude modulation of an optical beam. An exemplary system may include a birefringent fiber positioned between two polarizers, or between a polarized input light source and an output polarizer. Light may enter the birefringent fiber as linearly polarized. Depending on birefringence and orientation of the birefringent fiber, the polarization state changes as the light propagates through the birefringent fiber. This changed polarization state then enters the output polarizer, for which transmission is a function of the polarization state and the relative orientation of the polarization axis. The polarization state emerging from the birefringent fiber may be changed by modulating the fiber birefringence, for example through application of an external stress. Net transmittance of the system may be varied according to a magnitude of an external force (e.g., pressure) to some or all of the birefringent fiber.