Some implementations of the disclosure relate to an optical system, including: a first light source; a secondary light source that is optically coupled to the first light source; a reflective element that is transparent with respect to the first light source but reflective with respect to the secondary light source, the reflective element being disposed between the first light source and the secondary light source; and a semi-reflective layer disposed on the secondary light source, such that reflection of light from the secondary light source by the reflective element and back through the semi-reflective element results in greater than 25% of the light from first light source exiting the optical system.

An optical device is described. The optical device includes a waveguide and a modulation driver. The waveguide includes a first region, a second region, and a tapered region between the first and second regions. The first region supports a first set of modes of an optical signal. The second region supports a second set of modes of the optical signal. The first set of modes is different from the second set of modes. The tapered region is between the first region and the second region. The waveguide includes lithium. The modulation driver is configured to provide modulation of the optical signal in the first region.

Some implementations of the disclosure relate to an optical system, including: a first light source; a secondary light source that is optically coupled to the first light source; a reflective element that is transparent with respect to the first light source but reflective with respect to the secondary light source, the reflective element being disposed between the first light source and the secondary light source; and a semi-reflective layer disposed on the secondary light source, such that reflection of light from the secondary light source by the reflective element and back through the semi-reflective element results in greater than 25% of the light from first light source exiting the optical system.

A control apparatus for generating a control signal for an electro-optic modulator is described. The control apparatus includes an RF signal source being configured to generate a radio frequency (RF) signal. The control apparatus further includes an amplitude adjustment circuit being configured to adjust an amplitude of the RF signal, thereby obtaining an adjusted RF signal. The control apparatus further includes a DC signal source being configured to generate a direct current (DC) signal. The control apparatus further includes a superposition circuit being configured to superimpose the adjusted RF signal and the DC signal, thereby obtaining the control signal for the electro-optic modulator. The control apparatus further includes a control circuit, wherein the control circuit is configured to receive at least one frequency parameter associated with the electro-optic modulator. The at least one frequency parameter includes a frequency multiplication factor and/or a target modulation frequency. The control circuit is configured to control the DC signal source to adapt a voltage of the DC signal based on the at least one frequency parameter received. Further, an optical signal generator apparatus and an RF-over-fiber system are described.

An integrated optical modulator includes, in part, a pair of waveguides and an inductor. The first waveguide is adapted to receive an incoming optical signal. The second waveguide includes a portion placed in proximity of the first waveguide so as to enable the incoming optical signal travelling in the first waveguide to couple to the second waveguide. The second waveguide comprises a p-n junction. The inductor has a first terminal coupled to the p-n junction and a second terminal coupled to a contact pad. The second waveguide has a circular shape. The inductor optionally has a spiral shape.

An optical filter device may include an optical fiber having a core and a cladding surrounding the core, the optical fiber having a tapered portion. The optical filter device may include an index selectable material surrounding the tapered portion and having an index of refraction being selectable based upon a physical characteristic. The optical filter device may include a device configured to change the index selectable material to select the index of refraction to selectively filter out a mode within the optical fiber.

An optical filter device may include an optical fiber having a core and a cladding surrounding the core, the optical fiber having a tapered portion. The optical filter device may include an index selectable material surrounding the tapered portion and having an index of refraction being selectable based upon a physical characteristic. The optical filter device may include a device configured to change the index selectable material to select the index of refraction to selectively filter out a mode within the optical fiber.

Techniques for coupling light into graphene using a planar photonic crystal having a resonant cavity characterized by a mode volume and a quality factor and at least one graphene layer positioned in proximity to the planar photonic crystal to at least partially overlap with an evanescent field of the resonant cavity. At least one mode of the resonant cavity can couple into the graphene layer via evanescent coupling. The optical properties of the graphene layer can be controlled, and characteristics of the graphene-cavity system can be detected. Coupling light into graphene can include electro-optic modulation of light, photodetection, saturable absorption, bistability, and autocorrelation.

Some implementations of the disclosure relate to an optical system, including: a first light source; a secondary light source that is optically coupled to the first light source; a reflective element that is transparent with respect to the first light source but reflective with respect to the secondary light source, the reflective element being disposed between the first light source and the secondary light source; and a semi-reflective layer disposed on the secondary light source, such that reflection of light from the secondary light source by the reflective element and back through the semi-reflective element results in greater than 25% of the light from first light source exiting the optical system.

An integrated optical modulator includes, in part, a pair of waveguides and an inductor. The first waveguide is adapted to receive an incoming optical signal. The second waveguide includes a portion placed in proximity of the first waveguide so as to enable the incoming optical signal travelling in the first waveguide to couple to the second waveguide. The second waveguide comprises a p-n junction. The inductor has a first terminal coupled to the p-n junction and a second terminal coupled to a contact pad. The second waveguide has a circular shape. The inductor optionally has a spiral shape.