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In this letter, the microfluidic optical fiber devices composed of microchannel are modeled and thoroughly analyzed. The microchannel intersecting the fiber core allows direct infusion of surrounding substances for detection. The simulation results suggest that the dimension of the microchannel can significantly affect the detection sensitivity of the device. In addition, the off-center position of the microchannel also plays an important role in shaping the device performance. The optimized microfluidic device can be used for sensitive refractive index sensing and biosensing applications. [ABSTRACT FROM PUBLISHER]

Coupling light into a silicon-on-insulator photonic chip has always been the first hurdle to overcome when using photonic integrated circuits. For applications that require robust, low-noise performance, and high degree of multiplexing, flood illuminating an array of vertical grating couplers is a promising approach to couple input light into the chip waveguides. This technique provides a very high alignment tolerance and allows simultaneous excitation of multiple waveguides for rapid parallel readout. However, parasitic reflections of the coupled light on the chip substrate introduce interferences and limit the device performance. We investigate the use of grating structures implemented on the chip surface to limit these parasitic signals and demonstrate a significant reduction of the coupling noise. [ABSTRACT FROM PUBLISHER]

We proposed and experimentally demonstrated a cost-efficient and easy-to-fabricate flexible thin-film nanocrystal quantum dot (NCQD) photodetector, by sandwiching a piece of NCQD-soaked tracing paper between two PEDOT:PSS electrodes. The highly conductive and transparent multilayer polymer electrodes are printed with an office inkjet printer without further patterning on commercial unmodified transparency films. The tracing paper is able to act as both the bed for NCQD attachment and the interspacing layer to prevent short-circuiting in vertical devices. Consistent increase in device performance is observed when the bending radius becomes smaller. Linear I-V characteristics are obtained, which show our device structure works as a photoconductor. [ABSTRACT FROM PUBLISHER]

We present experimental results on the development of bottom-emitting GaInNAs vertical-cavity surface-emitting lasers (VCSELs) operating at wavelengths near 1300 nm. This development effort is based on the modification of oxide-apertured top-emitting structures to allow emission through the GaAs substrate. Similar device performance was seen in both the top- and bottom-emitting structures. Single-mode output powers (adjusted for substrate absorption) of ∼0.75 mW, with threshold currents of 1.3 mA, were achieved with ∼3.5-μm aperture diameters. Larger multimode devices exhibited a maximum adjusted output power of 2.2 mW. To the best of our knowledge, these are the first bottom-emitting flip-chip compatible 1300-nm VCSELs fabricated with GaInNAs-GaAs active regions. [ABSTRACT FROM PUBLISHER]

High-performance 1.3-μm-emitting quantum-dot lasers were fabricated by self-organized growth of InAs dots embedded in GaInAs quantum wells. The influence of the number of quantum-dot layers on the device performance was investigated. Best device results were achieved with six-dot layers. From the length dependence; a maximum ground state gain of 17 cm-1 for six dot layers could be determined. Ridge waveguide lasers with a cavity length of 400 μm and high-reflection coatings show threshold currents of 6 mA and output powers of more than 5 mV. Unmounted devices can be operated in continuous wave mode up to 85°C. A maximum operating temperature of 160°C was achieved in pulsed operation for an uncoated 2.5-mm-long ridge waveguide laser [ABSTRACT FROM PUBLISHER]

We have investigated the dependence of the light-current characteristics of broad-area lasers with different p-doping profiles for a two-step separate-confinement heterostructure (SCH) 1.55-μm InGaAs-InP laser. A sizable increase of the optical output power is observed in a structure with delta doping at the heterointerfaces and moderate doping in the thick SCH layer. It is also shown that the characteristic temperature (T0) of the structure with delta doping at the heterointerfaces and moderate doping at the thick SCH layer is almost constant as the measurement temperature is increased. Such an improvement in device performance is attributed to a reduction of carrier leakage to the SCH layer [ABSTRACT FROM PUBLISHER]

Excellent lasing properties and temperature characteristic of a highly strained 1.17-μm GaInAs-GaAs double-quantum-well laser are reported. We show that a strained buffer layer, which is employed in the device, has no tradeoff on the device performance. For a 1500-μm-long laser with cleaved facets a threshold current density of 200 A/cm2 is achieved. A transparency current density of 180 A/cm2 is estimated for as cleaved devices. A record high characteristic temperature in this wavelength range of 150 K is achieved [ABSTRACT FROM PUBLISHER]