A mid-infrared cascading fiber amplifier device having a source configured to generate a first electromagnetic wave output at a first frequency, a fiber coupled to the source and a pump coupled to the fiber and configured to generate a second electromagnetic wave output at a second frequency, wherein the second frequency is higher than the first frequency and causes the fiber to undergo two or more transitions in response to stimulation by the first electromagnetic wave output at the first frequency, wherein the first transition generates the first electromagnetic wave output approximately at the first frequency and the second transition generates the first electromagnetic wave output approximately at the first frequency.

The invention relates to a switchable absorber element and a photovoltaic cell based thereon. A switchable absorber element according to the invention has an absorber layer. The absorber element furthermore has at least one front side reflection layer and at least one rear side reflection layer, wherein the absorber layer is arranged between front side reflection layer and rear side reflection layer, wherein the optical path length between front side reflection layer and rear side reflection layer is less than 400 nm at least for light impinging perpendicularly onto the cell. The absorber element according to the invention is characterized in that at least one of the reflection layers has a switchable reflectivity.

Systems and methods for imaging in the short wave infrared (SWIR), photodetectors with low dark current and associated circuits for reducing dark currents and methods for generating image information based on data of a photodetector array. A SWIR imaging system may include a pulsed illumination source operative to emit radiation pulses in the SWIR band towards a target resulting in reflected radiation from the target; (b) an imaging receiver including a plurality of Ge PDs operative to detect the reflected SWIR radiation and a controller, operative to control activation of the receiver for an integration time during which the accumulated dark current noise does not exceed the time independent readout noise.

A principle which enables the generation of macroscopic Fock and sub-Poissonian states is disclosed. Generic components of the system include: an electromagnetic structure (possessing one or more electromagnetic resonances), a nonlinear electromagnetic element (such as a nonlinear crystal near or inside the structure), and a source of light. In one embodiment, stimulated gain is used to create large numbers of photons in a cavity, but with very low photon number noise (uncertainty) in the cavity, and thus acts as a Fock laser. This Fock laser is capable of producing these states due to a very sharp intensity-dependent gain (or loss) that selects a particular photon number. The disclosed system and method are robust against both atomic and optical decoherence. Various examples of the new Fock laser design are also described.

Methods, apparatus, and systems for active saturable absorbance of an optical beam. An active saturable absorber may comprise an optical input to receive an optical beam, and one or more lengths of fiber between the optical input and an optical output. At least one of the lengths of fiber comprises a confinement region that is optically coupled to the output. The active saturable absorber may further comprise an optical detector to sense a characteristic of the optical beam, such as power. The active saturable absorber may further comprise a perturbation device to modulate, through action upon the one or more lengths of fiber, a transmittance of the beam through a fiber confinement region from a lower transmittance level to a higher transmittance level based on an indication of the characteristic sensed while the transmittance level is low.

A Q-switched laser includes a laser cavity including a cavity mirror and an output coupler mirror. The Q-switched laser also includes a doped laser gain material disposed in the laser cavity and a Q-switch including a saturable absorber comprising Fe.sup.2+:ZnSe or Fe.sup.2+:ZnS.

A mid-infrared cascading fiber amplifier device having a source configured to generate a first electromagnetic wave output at a first frequency, a fiber coupled to the source and a pump coupled to the fiber and configured to generate a second electromagnetic wave output at a second frequency, wherein the second frequency is higher than the first frequency and causes the fiber to undergo two or more transitions in response to stimulation by the first electromagnetic wave output at the first frequency, wherein the first transition generates the first electromagnetic wave output approximately at the first frequency and the second transition generates the first electromagnetic wave output approximately at the first frequency.

An optical device capable of an ultrafast and large change of its reflection or absorption coefficient upon being excited by an ultrafast optical pulse with wavelength in the visible, near-infrared, or infrared spectral regions. The optical device includes, in sequential order, a first thick metallic layer, a first dielectric layer, a second thin metallic layer, and a second dielectric layer. The optical device acts as a nonlinear mirror that presents a large reflectance at low irradiance and a low reflectance at large irradiance. The optical device can further act as a nonlinear mirror that presents a linear and nonlinear reflectance with a large angular bandwidth.

The present invention relates to a method of manufacturing large area graphene for graphene-based photonics devices such as bolometric graphene detectors, or for use as a saturable absorber in ultra-high bandwidth detectors for producing ultrafast laser pulses. The method includes: growing a first graphene layer on one side of a metal substrate, and a second graphene layer on another side of the metal substrate; coating the first graphene layer with a plurality of resist layers including a low molecular weight polymethylmethacrylate, and a high molecular weight polymethylmethacrylate; removing the second graphene layer and the metal substrate to reveal the first graphene layer; disposing the first graphene layer on an optical substrate; and removing the plurality of resist layers from the first graphene layer to reveal a final graphene layer, which can be used as the basis to manufacture a multilayer graphene structure for graphene detectors.

The present disclosure is directed to an optically active medium comprising dye aggregates and optionally a nucleotide oligomer or other nucleotide-based architecture, which may be used in in optical devices, in particular nonreciprocal devices (i.e., devices in which energy flows in one direction only), that can respond to differences in the polarization of light. An analysis is presented of the energy levels and the strengths of the optical transitions (changes in energy states) for a three-chromophore (dye) aggregate in which the chromophores are coupled with a J-like (i.e., end-to-end) stacking. Specific devices and methods of use are also disclosed herein.