A CMOS-compatible actuator platform for implementing phase, amplitude, and frequency modulation in silicon nitride photonic integrated circuits via piezo-optomechanical coupling using tightly mechanically coupled aluminum nitride actuators is disclosed. The platform, which may be fabricated in a CMOS foundry, enables scalable active photonic integrated circuits for visible wavelengths, and the piezoelectric actuation functions without performance degradation down to cryogenic operating temperatures. A number of devices are possible, including ring modulator devices, phase shifter devices, Mach-Zehnder interferometer devices, directional coupler devices (including tunable directional coupler devices), and acousto-optic modulator and frequency shifter devices, each of which can employ the same AlN actuator platform. As all of these devices can be built on the same AlN actuator platform, numerous optical functions can be implemented on a single die.

Systems and methods for steering an optical beam in two dimensions are disclosed. The system includes a substrate comprising an acousto-optic antenna array and an acoustic transducer. Each antenna of the antenna array includes a high-confinement surface waveguide carrying a light signal. The acoustic transducer imparts acoustic energy into each surface waveguide as a mechanical wave. Interaction of the light signal and mechanical wave in each surface waveguide induces light to scatter into free space. The light scattered out of the plurality of waveguides collectively defines the output beam. The longitudinal angle of output beam, relative to the substrate, is determined by the relative frequencies of the mechanical waves and the light signals. The transverse angle of the output beam is controlled by controlling the relative phases of the mechanical waves and/or light signals across the surface-waveguide array.

An embodiment apparatus comprises an optically transparent substrate having first and second surfaces; a piezoelectric membrane, arranged at the first surface, that oscillates in response to a light beam propagated through the substrate; at least one reflective facet facing the substrate and arranged at the piezoelectric membrane; and an optical element receiving the light beam at an input end and guiding the light beam towards an output end coupled to the second surface. The optical element incorporates a light focusing path focusing the light beam at a focal point at the piezoelectric membrane, and at least one light collimating path collimating the light beam onto the at least one reflective facet. The optical element guides light reflected from the at least one reflective facet to the input end, the reflected light indicating a position of the optical element with respect to the focal point.

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.

Apparatus is provided including an acoustic sensor (50) having an optical waveguide (20). The optical waveguide (20) includes a waveguide core (202) having a waveguide core refractive index and a waveguide core photo-elastic coefficient, and an over-cladding layer (204) coupled to the waveguide core (202) and including an optically transparent polymer having an over-cladding refractive index and an over-cladding photo-elastic coefficient. The waveguide core refractive index is greater than the over-cladding refractive index, and the over-cladding photo-elastic coefficient is greater than the waveguide core photo-elastic coefficient. Other applications are also described.

The present Specification is directed to devices for controlling the phase of a light signal in a surface waveguide of a planar-lightwave circuit by controlling a stress in the waveguide material. Phase controllers disclosed can impart stresses of opposite signs in a material such that a desired effect on the refractive index of an optical material can be accentuated. As a result, a greater change in the refractive index of the material can be realized in a phase controller that requires less chip real estate and/or at lower voltages. In some embodiments, a phase-control module includes a pair of complimentary stress-optic phase controllers, one having electrodes disposed on the top and bottom of a piezoelectric layer, while the other has electrodes disposed only on top of the piezoelectric layer. As a result, the phase controllers impart stress of opposite sign in the material beneath them.

Optical fiber assemblies for filtering of higher-order modes include a winding support and an optical fiber wound along a winding path on the winding support. The optical fiber is configured to support a fundamental transverse mode and one or more higher-order transverse modes. The optical fiber has a longitudinal fiber axis, a core, a cladding surrounding the core, a transverse cross-section lacking circular symmetry, and a rotation imparted thereto about the longitudinal fiber axis. The rotation and winding of the optical fiber provide stronger attenuation of the one or more higher-order transverse modes as compared to the fundamental transverse mode. In some implementations, the winding path has a non-constant radius of curvature. In other implementations, the optical fiber has a diameter larger than 10 micrometers and at least one stress-applying part arranged in the cladding about the core. Methods perform higher-order-mode filtering.

A planar lightwave circuit that can be optically coupled with an external device with low optical loss, while also providing low-power functional control over an optical signal propagating through the PLC is disclosed. The PLC includes a high-contrast waveguide region in a stress-inducing (SI) phase shifter is formed such that it can control the phase of the optical signal. The high-contrast-waveguide region is optically coupled to a low-contrast-waveguide region via a spotsize converter, thereby enabling optical coupling to off-chip devices with low optical loss. Formation of the SI phase shifter in a high-contrast-waveguide region enables improved responsivity and phase control, reduced voltage, and smaller required chip real estate. As a result, the present invention enables lower-cost and higher-performance PLC systems.

A phase modulator for a light beam comprising a waveguide having a longitudinal axis, and a piezoelectric actuator to apply a mechanical stress within said waveguide in response to an electrical bias, said actuator comprising a first part covering a first side of the waveguide and having a first axis of symmetry essentially parallel to the longitudinal axis. The actuator comprises a second part covering a second side of the waveguide, said second part having a second axis of symmetry essentially parallel to the longitudinal axis.

An embodiment apparatus comprises an optically transparent substrate having first and second surfaces; a piezoelectric membrane, arranged at the first surface, that oscillates in response to a light beam propagated through the substrate; at least one reflective facet facing the substrate and arranged at the piezoelectric membrane; and an optical element receiving the light beam at an input end and guiding the light beam towards an output end coupled to the second surface. The optical element incorporates a light focusing path focusing the light beam at a focal point at the piezoelectric membrane, and at least one light collimating path collimating the light beam onto the at least one reflective facet. The optical element guides light reflected from the at least one reflective facet to the input end, the reflected light indicating a position of the optical element with respect to the focal point.