| 1. |
- Ramos Santesmases, David, et al.
(author)
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Optical concentration in fully delineated mid-wave infrared T2SL detectors arrays
- 2023
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 123:18
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Journal article (peer-reviewed)abstract
- The dependence of quantum efficiency (QE) on fill factor and pixel pitch is studied theoretically and experimentally in fully delineated type-II superlattice (T2SL) detectors. Theoretically, a 2-dimensional simulation model is used to compute the absorption in the array geometry, which shows an insensitivity of the optical response to the fill factor. This is a result of the photodiode array (PDA) geometry concentrating the light in the pixel area. QE measurements on PDAs with varying pixel pitch (from 225 to 10 μm) and fill factors (from 98% to 64%) confirm this independence of the QE on the fill factor and results in a 50% increase in the photocurrent density in 10 μm pitch PDAs compared to 225 μm pitch PDAs. Furthermore, measurements of the dark current density vs pixel size revealed an absence of surface leakage in these PDAs, which, combined with the increased photocurrent density results in an improved signal-to-noise ratio when reducing the pitch in these T2SL detectors. Finally, this result resolves the QE-modulation transfer function trade-off, as the electrical isolation of the pixel is carried out without impacting the QE of the array.
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| 2. |
- Ramos Santesmases, David, et al.
(author)
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Simulation and Characterization of the Modulation Transfer Function in Fully Delineated Type-II Superlattices Infrared Detectors
- 2024
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In: IEEE Transactions on Electron Devices. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9383 .- 1557-9646. ; 71:4, s. 2459-2464
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Journal article (peer-reviewed)abstract
- The modulation transfer function (MTF) in fully delineated 15 μ m pitch type-II superlattice (T2SL) mid-wave infrared (IR) detectors is studied theoretically and experimentally. Theoretically, a 2-D model to simulate the spot scan (SS) profile is presented and used to compute the MTF as a function of the wavelength and the array geometry (pitch size, trench width). The dependence of the detector trench on the MTF is also evaluated experimentally by the edge spread function (ESF) method according to the ISO12233 standard. The experimental results show an excellent agreement with the theoretical model, reporting an MTF of 0.61 and 0.60 at the Nyquist frequency for 1 and 2 μ m trench, respectively. With the simulation model, the effect of the increased optical crosstalk for smaller pixel pitch is discussed as a function of the trench width (0.5, 1, and 2 μ m) and incidence angle up to ± 30 ∘ . Simulation results show MTF values at the Nyquist frequency between 0.61–0.62, 0.58–0.60, and 0.55–0.57 with an average degradation of 1%, 2%, and 7% at an angle of ± 30 ∘ compared to normal incidence for the 10, 7.5, and 5 μ m pitch, respectively.
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| 3. |
- Claesson, Åsa, et al.
(author)
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Internal Electrode Fiber Polarization Controller
- 2003
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In: Conf Opt Fiber Commun Tech Dig Ser. ; , s. 39-40
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Conference paper (peer-reviewed)abstract
- Potentially low-cost polarization controllers were studied with a current-driven internal electrode fibers. The return loss was determined for the device. An EDFA was used as light source, and five devices were constructed and tested. The polarization dependent loss (PDL) of the polarization controllers was measured between 1530 nm and 1570 nm using the Jones-matrix method. The response times for the controllers was found to be relatively slow. The rise time of the optical response was significantly improved by overshooting the current pulse.
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