In this paper, we present a single-pixel hyperspectral imager based on Hadamard transformat ion. The imager uses a micromirror array and a resonant scanning mirror to implement spatial and spectral encoding. For a proof of concept, the sensing wavelength of the imager is 450nm to 750nm, but it can easily be applied to the infrared wavelengths. It has high robustness and high frame rate compared with conventional single-pixel hyperspectral imagers. We also introduce a cascading method that can enhance the spatial resolution of the single-pixel hyperspectral imager. Some experimental results are presented in the paper to demonstrate the performance of our proposed system.
Novel concepts of on-chip Fourier transform spectrometers is proposed. The principal element in the spectrometer is semiconductor waveguide directional couplers. The optical path difference can be tuned by varying the coupling length or influencing the propagation mode of the directional coupler. Solutions of both these two methods are proposed, and the theories are verified by spectra recovering. They function well around 1.5 μm wavelength. Further enhancement can be achieved by cascading more stages of directional couplers or extending the coupling length. This design meets the requirement of small size, weight and power and may be useful in future on-chip spectroscopic sensors.
The design of quantum dot infrared photodetector (QDIP) based on metal-insulator-metal (MIM) microcavity in which the quantum dot (QD) is sandwiched between a planar metallic film and a metallic stripe is reported. By a finite difference time-domain (FDTD) method, the light coupling efficiency spectra and enhancement factor are numerically calculated. The results exhibit that the total electric field concentrated in metal-metal region is strongly enhanced when the resonant frequency of microcavity is equal to the QD’s peak response frequency. This enhancement effect mainly originates from the resonant coupling of incident photons into microcavity forming the surface plasmonic mode. The optimization of structural parameters for MIM microcavity is discussed, demonstrating an optimal structure of quantum dot infrared photodetector with the coupling efficiency improved nearly 7 times compared with conventional mesa QDIPs. So, it is deduced that a favorable performance of device such as high quantum efficiency and infrared responsivity is possible. Finally, the detector shows the potential application in the infrared sensing and imaging, as well as integrating with other electronic and optoelectronic device for the sub-wavelength size.
Near infrared light emitting diodes (LEDs) play an important role in infrared photodetectors; however, external quantum efficiency of GaAs LEDs is greatly confined as a result of critical angle and Fresnel diffraction. In this study, polystyrene spheres are used to fabricate photonic crystal. A ring-shaped ohmic contact was introduced to the device, and the current-voltage curves and light emitting efficiency were measured to characterize the property of device. The LED device with surface nano-structure exhibited better external quantum efficiency (EQE) and improved light extraction efficiency (LEE) in near infrared light emitting area compared to non-structure device.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.