Abstract: System, including methods and apparatus, for light detection and signal processing for droplet-based assays. An exemplary system provides a method of detection for droplets. An examination region of a channel may be illuminated with first pulses of light interleaved with second pulses of light as droplets pass through the examination region, the first pulses being spectrally distinct from the second pulses. Data may be collected representing light detected during illumination of the examination region with the first pulses and the second pulses. Each droplet may be illuminated with a beam of light that is narrower than a diameter of the droplets.

Abstract: An optical sensor apparatus includes an optically transmissive structure having planar first, second, and third faces, two or more light sources located outside the structure adjacent the first face, and a photodetector array located outside the prism adjacent the first face. The structure, light sources, and photodetector array are configured such that light from the light sources that is totally internally reflected at an optical interface between the prism and a sample outside the structure proximate the second face is reflected at the third face and incident on a portion of the photodetector array that depends on a refractive index of the sample. The light sources are positioned with respect to the structure and photodetector array such that the totally internally reflected light from each light source corresponds to a different range of refractive index of the sample and maps to a corresponding portion of the photodetector array.

Abstract: A nonlinear optical system may include optics, a non-linear optical crystal, and a uni-axial focusing element. The non-linear optical crystal is configured to generate an output beam from a non-linear optical interaction with an input beam. The optics are configured to image the input beam to an original input beam waist within the non-linear optical crystal, whereby the output beam has an original output beam waist. The uni-axial focusing element is optically coupled to the non-linear optical crystal. The uni-axial focusing element is configured so that the output beam has a new output beam waist at approximately the same location as the original output beam waist.

Abstract: The present invention provides a high-speed Quantum Efficiency (QE) measurement device that includes at least one device under test (DUT), at least one conditioned light source with a less than 50 nm bandwidth, where a portion of the conditioned light source is monitored. Delivery optics are provided to direct the conditioned light to the DUT, a controller drives the conditioned light source in a time dependent operation, and at least one reflectance measurement assembly receives a portion of the conditioned light reflected from the DUT. A time-resolved measurement device includes a current measurement device and/or a voltage measurement device disposed to resolve a current and/or voltage generated in the DUT by each conditioned light source, where a sufficiently programmed computer determines and outputs a QE value for each DUT according to an incident intensity of at least one wavelength of from the conditioned light source and the time-resolved measurement.

Abstract: System, including methods and apparatus, for light detection and signal processing for droplet-based assays.

Abstract: Systems, methods, and apparatus by which solar energy may be collected to provide electricity are disclosed herein.

Abstract: The present invention provides a high-speed Quantum Efficiency (QE) measurement device that includes at least one device under test (DUT), at least one conditioned light source with a less than 50 nm bandwidth, where a portion of the conditioned light source is monitored. Delivery optics are provided to direct the conditioned light to the DUT, a controller drives the conditioned light source in a time dependent operation, and at least one reflectance measurement assembly receives a portion of the conditioned light reflected from the DUT. A time-resolved measurement device includes a current measurement device and/or a voltage measurement device disposed to resolve a current and/or voltage generated in the DUT by each conditioned light source, where a sufficiently programmed computer determines and outputs a QE value for each DUT according to an incident intensity of at least one wavelength of from the conditioned light source and the time-resolved measurement.

Abstract: Methods and apparatus for managing thermal loads on a laser gain medium and for boosting the output power of a diode pumped laser are disclosed. The short-term average pumping power to the gain medium is increased, to provide a burst of pumping energy to the laser gain medium. A subsequent short-term reduction in the average pumping power then allows the gain medium to cool to a desired state steady level. The average pumping power is then increased to maintain this steady state level until the next burst is desired. For example, a pulse of current may be applied to a laser diode at a first current level I1 for a first time interval ?t1, where I1 exceeds a nominal current value Inom by an amount ?I1. The current to the laser diode is reduced to a second current level I2 for a second time interval ?t2, where Inom exceeds I2 by an amount ?I2. To balance the thermal load on the diode an integral of ?I1 over the time ?t1 is approximately equal in magnitude to an integral of ?I2 over the time ?t2.

Abstract: Switchable power combining is provided using a tunable arrayed waveguide grating (AWG) as the combining element. The AWG has two or more inputs and two or more outputs. Each AWG input is bi-directionally coupled to a corresponding laser source, and each laser source has substantially the same gain spectrum. All sources are coupled to a selected one of the AWG outputs, without substantial coupling of the sources to any other AWG output. The AWG is tunable, such that any one of its outputs can be thus selected. The selected output provides optical feedback, thereby feedback stabilizing the emission wavelengths of the sources to values suitable for single-mode combining. According to a further aspect of the invention, a piezo-electrically tunable AWG is provided. The AWG has a piezo-electric transducer bonded to the waveguide array section of the AWG. Strain induced in the waveguide array by the transducer can alter optical path lengths of the waveguide, thereby tuning the AWG.

Abstract: Optical waveguide devices characterized by low loss for a fundamental mode and high loss for higher order modes are disclosed. The high loss is sufficiently high that the waveguide is effectively single-moded.

Abstract: Quasi-phasematching design to provide an approximation to a desired spectral amplitude response A(f) is provided. An initial phase response ?(f) corresponding to A(f) is generated. Preferably, d2?(f)/df2 is proportional to A2(f). Alternatively, ?(f) can be a polynomial in f. A function h(x) is computed such that h(x) and H(f)=A(f)exp(i?(f)) are a Fourier transform pair. A domain pattern function d(x) can be computed by binarizing h(x) (i.e., approximating h(x) with a constant-amplitude approximation). In some cases, the response provided by this d(x) is sufficiently close to A(f) that no further design work is necessary. In some embodiments of the invention, the need for binarization can be reduced or eliminated by providing amplitude modulation of the effective nonlinearity.

Abstract: Quasi-phasematching design to provide an approximation to a desired spectral amplitude response A(f) is provided. An initial phase response ?(f) corresponding to A(f) is generated. Preferably, d2?(f)/df2 is proportional to A2(f). Alternatively, ?(f) can be a polynomial in f. A function h(x) is computed such that h(x) and H(f)=A(f)exp(i?(f)) are a Fourier transform pair. A domain pattern function d(x) can be computed by binarizing h(x) (i.e., approximating h(x) with a constant-amplitude approximation). In some cases, the response provided by this d(x) is sufficiently close to A(f) that no further design work is necessary. In some embodiments of the invention, the need for binarization can be reduced or eliminated by providing amplitude modulation of the effective nonlinearity.

Abstract: A split-band amplifying apparatus that has a first section for amplifying a long wavelength band of an optical signal and a second section equipped with a fiber amplifier for amplifying a short wavelength band of the optical signal. The fiber amplifier in the second section uses a short-pass fiber with a depressed cladding cross-section and core doped with an active material, e.g., Erbium, and pumped to a high relative inversion D. The split-band amplifying apparatus can be used to amplify signals whose short wavelength band includes at least a portion of the S-band and whose long wavelength band includes at least a portion of the C- and/or L-band.

Abstract: Co-doping the gain medium of a diode-pumped infrared laser to make the laser resistant to long-term degradation from high-intensity internal infrared radiation is disclosed. Co-doping the gain medium with ions such as Cr3+ and Ce3+ that make the gain medium resistant to external ionizing radiation solves problems of long-term degradation of the gain medium.

Abstract: A frequency-converted laser may be made with a non-linear material having a surface coated with an anti-reflection coating by measuring an absorbance of the anti-refection coating, and using the non-linear crystal for frequency conversion in the laser if the absorbance measured is less than a rejection threshold of about 100 parts-per-million or less.

Abstract: A method of producing a short-pass fiber by drawing a preform for a depressed cladding fiber at a predetermined drawing ratio. The preform has a core of refractive index n0, a depressed cladding surrounding the core and having a refractive index n1, and a secondary cladding surrounding the depressed cladding and having a refractive index n2. The core has a core cross-section and the depressed cladding has a depressed cladding cross-section that is larger than the core cross-section. The drawing ratio is determined based on the parameters of the preform measured along the axis of the preform and based on a desired minimum fundamental mode cutoff wavelength ?m. The final core cross-section defines a fundamental mode cutoff wavelength ?c such that ?c??m along the axis. Then the preform is pulled by the thus-determined drawing ratio to produce the short-pass fiber. In some embodiments a test section of the fiber is pulled first before pulling the short pass fiber.

Abstract: Methods and apparatus for managing thermal loads on a laser gain medium and for boosting the output power of a diode pumped laser are disclosed. The short-term average pumping power to the gain medium is increased, to provide a burst of pumping energy to the laser gain medium. A subsequent short-term reduction in the average pumping power then allows the gain medium to cool to a desired state steady level. The average pumping power is then increased to maintain this steady state level until the next burst is desired. For example, a pulse of current may be applied to a laser diode at a first current level I1 for a first time interval ?t1, where I1 exceeds a nominal current value Inom by an amount ?I1. The current to the laser diode is reduced to a second current level I2 for a second time interval ?t2, where Inom exceeds I2 by an amount ?I2. To balance the thermal load on the diode an integral of ?I1 over the time ?t1 is approximately equal in magnitude to an integral of ?I2 over the time ?t2.

Abstract: A fiber amplifier in which the active core is surrounded by a cladding and coupling of radiation between a core mode and cladding modes is suppressed to minimize cladding mode losses in a short wavelength range. An index profile is established in the active core and in the cladding such that the core exhibits a loss above a cutoff wavelength ?c and positive gains in the short wavelength range below the cutoff wavelength ?c. Suppression of cladding mode losses is achieved by an arrangement for suppressing the coupling of radiation in the short wavelength range between a core mode supported the active core and a cladding mode supported by the cladding. The arrangement for suppressing can include an absorbing material or a scattering material distributed in the cladding. The arrangement for suppressing can include a non-phase-matched length section of the fiber amplifier in which the core mode and the cladding modes are not phase matched.

Abstract: A fiber amplifier in a depressed cladding or W-profile fiber. The fiber has a core doped with the active material and defined by a core cross-section and a refractive index no. A depressed cladding of index n1 surrounds the core and a secondary cladding of index n2 surrounds the depressed cladding. The fiber amplifier is pumped to a level of high relative inversion, such that the active material exhibits positive gains in a short wavelength band and high gains in a long wavelength band. The core cross-section, the depressed cladding cross-section and the refractive indices no, n1, and n2 are selected to obtain a roll-off loss curve about a cutoff wavelength ?c. The roll-off loss curve yields losses at least comparable to the high gains in the long wavelength band and losses substantially smaller than the positive gains in the short wavelength band.

Abstract: An optical communication system such as a Wavelength-Division-Multiplexed (WDM) or Dense Wavelength-Division-Multiplexed (DWDM) communication system using Erbium doped fiber amplifiers (EDFAs) for amplifying signals in the S-band. The fiber amplifier has a core doped with Erbium and defined by a core cross-section and a refractive index n0. The fiber amplifier has a depressed cladding surrounding the core and a secondary cladding surrounding the depressed cladding. The depressed cladding has a depressed cladding cross-section and a refractive index n1, and the secondary cladding has a secondary cladding cross-section and a refractive index n2. The fiber amplifier has a pump source for pumping the Erbium to a level of high relative inversion D such that the Erbium exhibits positive gains in the S-band and high gains in a long wavelength band longer than the S-band, i.e., in the C- and L-Bands.