Responsivity

About: Responsivity is a research topic. Over the lifetime, 9918 publications have been published within this topic receiving 186118 citations.

High and flat spectral responsivity of quartz tuning fork used as infrared photodetector in tunable diode laser spectroscopy

Abstract: Infrared laser technology over the last decades has led to an increasing demand for optical detectors with high sensitivity and a wide operative spectral range suitable for spectroscopic applications. In this work, we report on the performance of a custom quartz tuning fork used as a sensitive and broadband infrared photodetector for absorption spectroscopy. The photodetection process is based on light impacting on the tuning fork and creating a local temperature increase that generates a strain field. This light-induced, thermoelastic conversion produces an electrical signal proportional to the absorbed light intensity due to quartz piezoelectricity. A finite-element-method analysis was used to relate the energy release with the induced thermal distribution. To efficiently exploit the photo-induced thermoelastic effects in the low-absorbance spectral region of quartz also, chromium/gold layers, acting as opaque surface, have been deposited on the quartz surface. To demonstrate the flat response as photodetectors, a custom tuning fork, having a fundamental resonance frequency of 9.78 kHz and quality factor of 11 500 at atmospheric pressure, was employed as photodetector in a tunable diode laser absorption spectroscopy setup and tested with five different lasers with emission wavelength in the 1.65–10.34 μm range. A spectrally flat responsivity of ∼2.2 kV/W was demonstrated, corresponding to a noise-equivalent power of 1.5 nW/√Hz, without employing any thermoelectrical cooling systems. Finally, a heterodyne detection scheme was implemented in the tunable diode laser absorption spectroscopy setup to retrieve the resonance properties of the quartz tuning fork together with the gas concentration in a single, fast measurement.

Bolometric response in graphene based superconducting tunnel junctions

Abstract: We fabricate graphene-TiOx-Al tunnel junctions and characterize their radio frequency response. Below the superconducting critical temperature of Al and when biased within the superconducting gap, the devices show enhanced dynamic resistance which increases with decreasing temperature. Application of radio frequency radiation affects the dynamic resistance through electronic heating. The relation between the electron temperature rise and the absorbed radiation power is measured, from which the bolometric parameters, including heat conductance, noise equivalent power and responsivity, are characterized.

Active resonance wavelength stabilization for silicon microring resonators with an in-resonator defect-state-absorption-based photodetector.

Abstract: We propose and demonstrate active resonance wavelength stabilization for silicon microring resonators with an in-resonator defect-state-absorption (DSA)-based photodetector (PD) for optical interconnects. We integrate an electro-optic (EO) tuner and a thermo-optic (TO) tuner on the microring, which are both feedback-controlled following a photocurrent threshold-detection method. Our BF2-ion-implanted DSA-based PIN PD exhibits a cavity-enhanced sub-bandgap responsivity at 1550 nm of 3.3 mA/W upon −2 V, which is 550-fold higher than that exhibited by an unimplanted PIN diode integrated on the same microring. Our experiment reveals active stabilization of the resonance wavelength within a tolerance of 0.07 nm upon a step increment of the stage temperature by 7 °C. Upon temperature modulations between 23 °C and 32 °C and between 18 °C and 23 °C, the actively stabilized resonance exhibits a transmission power fluctuation within 2 dB. We observe open eye diagrams at a data transmission rate of up to 30 Gb/s under the temperature modulations.

Gate‐controlled Hg1−xCdxTe photodiodes passivated with native sulfides

Abstract: The properties of ion‐implanted junctions in Hg1−xCdxTe with x=0.22, passivated by a novel native sulfide technique, are described. The junctions are typically operated at 77 K, with 50% responsivity at a wavelength of 10.5 μm. To study the effects of the passivated surface on the diode properties, special gate‐controlled diodes were processed, including both nickel and titanium gate metals. In addition, a novel enhancement mode metal–insulator–semiconductor field‐effect transistor (MISFET) is presented. The measured dc properties and noise current spectral densities of various diodes as a function of reverse bias and gate control voltage show that close to background limited devices may be realized with the above surface passivation. In particular, such diodes exhibit good 1/f noise performance at low frequency, with reverse bias of close to 200 mV, without requiring a special gate electrode.

A new method for the spectral characterisation of PV modules

Abstract: This paper presents a new characterisation method for the spectral influence of solar irradiation on photovoltaic (PV) modules, based on a proposed analytical model for the effective responsivity of PV modules. This mathematical tool needs only easily measurable atmospheric parameters and is applicable to different technologies. It allows the calculation of the spectral influence on PV modules under field conditions. It has been observed that this influence depends strongly on sky conditions and also on the PV module tilt angle, its technology, and the time of the year. Opposite effects are observed between cloudy and clear sky conditions, concluding that the former especially favours PV conversion in amorphous silicon modules. Copyright © 1999 John Wiley & Sons, Ltd.