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Half-wave plate (HWP) is one of the key polarization controlling devices in optical systems. The conventional HWPs based on birefringent crystals are inherently bulky and difficult to be monolithically integrated with other optical components. In this work, metasurface-based HWPs with high compactness are demonstrated on a 12-inch silicon complementary metal-oxide-semiconductor platform. Three-dimensional finite difference time domain simulation is used to design the nanostructure and investigate the impact of fabrication process variation on the device performance. In addition, the cross- and co-polarization transmittance (Tcross and Tco) of the HWPs located at different wafer locations are characterized experimentally. The peak Tcross and valley Tco values of 0.69 ± 0.053 and 0.032 ± 0.005 are realized at the wavelength around 1.7 μm, respectively. This corresponds to a polarization conversion efficiency of 95.6% ± 0.8%.

infrared photodetectors have been used extensively in biomedicine, surveillance, communication and astronomy. however, state of the art technology based on Ⅲ-Ⅴ and Ⅱ-Ⅵ compounds still lacks excellent performance for high-temperature operation. surface plasmon polaritons (spps) have demonstrated their capability in improving the light detection from visible to infrared wave range due to their light confinement in subwavelength scale. advanced fabrication techniques such as electron-beam lithography (ebl) and focused ion-beam (fib), and commercially available numerical design tool like finite-difference time-domain (fdtd) have enabled rapid development of surface plasmon (sp) enhanced photodetectors. in this review article, the basic mechanisms behind the sp-enhanced photodetection, the different type of plasmonic nanostructures utilized for enhancement, and the reported sp-enhanced infrared photodetectors will be discussed.

We report a detailed comparative investigation of resonance behaviors and sensing capability of gold U-shape spilt-ring resonator (U-SRR) and fourfold rotated SRR (U4-SRR) metasurfaces in near- and middle-infrared (IR) range. All the resonant modes of the U4-SRR metasurfaces occur at longer wavelengths compared to the U-SRR metasurfaces with the same U size. Stronger field intensities are observed in all the three resonance modes of the U4-SRR metasurfaces and the intensity in the fundamental magnetic (m0) mode is almost three times of that of U-SRR metasurface under unpolarized incidence. All the three peak resonance wavelengths shift to longer wavelengths and the sensitivity increases with the increase of U size. A sensitivity of 642 nm RIU−1 is obtained in the U4-SRR metasurface for unpolarized incidence. This provides an excellent candidate for high performance sensing in the near- and mid-IR regions without polarization concern. [ABSTRACT FROM AUTHOR]

We report high quality GeSn/GaAs heterostructure photodetectors grown by a modified magnetron sputtering system. A metal-semiconductor-metal photoconductor is fabricated to examine the ability of photodetection for GeSn alloy. Then the GeSn/GaAs heterostructure photodetector is first demonstrated with a detectivity of $1.8\times 10^{9}$ Jones achieved at 1450 nm under an applied reverse voltage bias of −0.1 V, which is comparable to or even better than the GeSn-based photodetectors grown by chemical vapor deposition. The work provides an alternative technique for low cost and large-area fabrication of GeSn based devices. [ABSTRACT FROM AUTHOR]

Strong plasmon–exciton interactions in monolayer transition‐metal dichalcogenides (TMDs) is emerging as a promising material platform for light emissions, nonlinear optics, and quantum communications, and their realizations require highly localized electric fields parallel to the transition dipole moment of TMD excitons. Here, a systematic study of light–matter interaction in planar dimer nanoantenna of nanoscale gaps coupled with monolayer WS2 is presented, where the effects of the local field enhancement and spatial mode overlap in the plasmon–exciton coupling strength are experimentally investigated. Importantly, anticrossing behaviors in the strong coupling regime with a Rabi splitting of Ω = 118 meV for gold bowtie antennas with 7 nm gaps and Ω = 138 meV for gold dimer arrays with 10 nm gaps are demonstrated. [ABSTRACT FROM AUTHOR]

We report the growth of direct bandgap single-crystalline Ge1−xSnx thin films on unheated substrates by a modified magnetron sputtering system. The Ge1−xSnx thin films were deposited on Si, Ge, and GaAs substrates at room temperature. They were characterized by X-ray diffraction and X-ray photoelectron spectroscopy that revealed the existence of Ge1−xSnx (004) peak and Ge-Sn bonds. Transmission and photoluminescence (PL) measurements confirm the direct bandgap dominated transition, and the bandgap values obtained are in agreement with the results calculated by 8-band k.p method. This article provides a simple and cost-effect way for fabrication direct bandgap GeSn films. [ABSTRACT FROM AUTHOR]

We comprehensively study the characteristics of dark current for a p-i-n heterostructure photodiode. To reduce the dark current, a wide-bandgap layer (AlGaSb) and thin quaternary layers (AlInAsSb) are inserted in the heterostructure for blocking the dark carrier diffusion and limiting type-II transition at interface, respectively. The activation energy derived from measurement results indicates the positive (negative) correlation between the dominant dark current density and voltage bias (temperature). Whatever the voltage bias (temperature), this relationship always exists, indicating the high stability and reliability of our devices. Indeed, the measures taken for reducing dark current are confirmed to be effective as the dark current density for this photodiode is limited to a lower level. For the typical square mesa with 350 μm side length, at the bias of −0.4 V, the dark current density is 1.78 A/cm2 for T=293 K, and reduces to 0.4 A/cm2 for T=77 K, where the room-temperature value is lower than or comparable with that of the state-of-the-art mid-infrared photodetectors. A room-temperature detectivity of 8.3 × 108 cm ⋅ Hz1/2/W with a cut-off wavelength of 4μm is demonstrated. [ABSTRACT FROM AUTHOR]

Half-wave plate (HWP) is one of the key polarization controlling devices in optical systems. The conventional HWPs based on birefringent crystals are inherently bulky and difficult to be monolithically integrated with other optical components. In this work, metasurface-based HWPs with high compactness are demonstrated on a 12-inch silicon complementary metal-oxide-semiconductor platform. Three-dimensional finite difference time domain simulation is used to design the nanostructure and investigate the impact of fabrication process variation on the device performance. In addition, the cross- and co-polarization transmittance (Tcross and Tco) of the HWPs located at different wafer locations are characterized experimentally. The peak Tcross and valley Tco values of 0.69 ± 0.053 and 0.032 ± 0.005 are realized at the wavelength around 1.7 μm, respectively. This corresponds to a polarization conversion efficiency of 95.6% ± 0.8%. [ABSTRACT FROM AUTHOR]

We present the design, fabrication, and characterization of middle-wavelength infrared photodetector based on active InAs0.9Sb0.1-based hetero-p-i-n structure grown on GaSb substrate. In this structure, the active absorption layer is sandwiched between thin quaternary p-type and n-type AlInAsSb layers and a heavily doped AlGaSb layer is introduced to reduce dark current. We observed good lattice matching between GaSb substrates and epitaxial layers by high-resolution X-ray diffraction. Photoluminescence (PL) spectrum at 13 K shows a full width at half maximum of ~ 29 meV, demonstrating good quality active absorption layers. The band gap energy of InAs0.9Sb0.1 is derived as ~ 0.322 eV at 0 K by Varshni fitting from PL spectra at different temperatures. A rather flat room-temperature responsivity of ~ 0.8-0.9 AW−1 over a wavelength range of ~ 2.1 µm is demonstrated without antireflection coating. A detectivity of 8.9 × 108 cm Hz1/2 W−1 at 3.5 µm for room-temperature operation is achieved under applied bias of − 0.5 V. [ABSTRACT FROM AUTHOR]

Middle wavelength infrared (MWIR) photodetectors have a wide range of applications, but almost all of them operate at low temperature due to the limit of materials and device structures. The capability of plasmonic structures to localize electromagnetic wave on the deep subwavelength scale provides the possibility for MWIR photodetectors operating at room temperature. Here, we report a high sensitivity room temperature MWIR photodetector which is an InAs0.91Sb0.09-based heterojunction n-i-p photodiode integrated with a Au-based two-dimensional subwavelength hole array (2DSHA). A room temperature detectivity of 0.8 × 1010 cm Hz1/2 W−1 and a response time of 600 ns are achieved. The non-cooling high performance of 2DSHA-InAs0.91Sb0.09 based heterojunction photodetectors will make their applications easier, broader, and economic. [ABSTRACT FROM AUTHOR]

We present the effect of interface quality on the performance of InAsSb based hetero n-i -p middle wavelength infrared (MWIR) photodiodes. By adopting heavily doping wide bandgap p- and n-type layers and inserting a thin layer between the two doped layers and the absorbing InAsSb region, the interface quality can be improved. We also employed proper fabrication processes in device fabrication to improve surface quality. It is found that the improved interface and surface quality can reduce the noise current and enhance detection performance. A detectivity of ∼1.5 × 10 9 cmHz 1/2 W −1 can be achieved at room temperature, and it can be increased to ∼4.0 × 10 9 cmHz 1/2 W −1 at 250 K. [ABSTRACT FROM AUTHOR]

Ge x Sn 1-x is one of the most promising materials in optoelectronics for its direct band-gap nature. In this paper, we report high-quality Ge and Sn thin films deposited on Si (001) substrates by magnetron sputtering. We found that the growth power and chamber pressure affect the quality of the Ge and Sn thin films significantly but in different ways. By optimizing the deposition conditions, high quality Ge and Sn films are achieved. A clear peak of Ge (004) phase in the x-ray diffraction (XRD) pattern which indicates a high-quality Ge lattice formed is observed, and post-treatment like rapid thermal annealing does not significantly affect the quality of the thin films. [ABSTRACT FROM AUTHOR]

We prepare undoped Mn 1.5 Co 1 Ni 0.5 O 4 and Cu and Sc co-doped Mn 1.5 Co 1 Ni 0.25 Cu x Sc 0.25−x O 4 (x = 0.05, 0.1, 0.15) films on Al 2 O 3 substrate by chemical solution deposition method. The crystallinity, surface morphologies, electrical transport property, optical property, and 1/ f noise property of these films are characterized. It shows that the Mn 1.5 Co 1 Ni 0.25 Cu 0.15 Sc 0.1 O 4 film possesses excellent electrical transport, optical and 1/ f noise properties compared with the other films. The absolute temperature coefficient of resistance and characteristic temperature of the Mn 1.5 Co 1 Ni 0.25 Cu 0.15 Sc 0.1 O 4 film are higher than that of Mn 1.5 Co 1 Ni 0.5 O 4 film, while its resistivity of 250 Ω·cm at 295 K is half of that Mn 1.5 Co 1 Ni 0.5 O 4 film. The transmittance and reflectance spectra of the films are measured and analyzed in the range of 0.55–2.0 µm, all the films show similar absorption structures in the measured spectrum. The 1/ f noise of the co-doped Mn 1.5 Co 1 Ni 0.5 O 4 films decreases significantly. The (γ/n)0.5/| TCR | value of the Mn 1.5 Co 1 Ni 0.25 Cu 0.15 Sc 0.1 O 4 reaches 2.3 × 10−12 cm1.5 K/% at 295 K, which is two orders lower than that of Mn 1.5 Co 1 Ni 0.5 O 4 film. Our results discover a thermosensitive material with excellent performance, which is expected to be applied to high performance uncooled infrared detectors. • We did a complete and systematic study for the Cu and Sc co-dopants effects on the electrical transport, optical, and low-frequency noise properties of Mn 1.5 Co 1 Ni 0.5 O 4 (MCN) thin films. • Mn 1.5 Co 1 Ni 0.25 Cu 0.15 Sc 0.1 O 4 thin film was found to be excellent electrical transport, optical and low-frequency noise performance, and we investigated and discussed the mechanisms of enhanced performance of the Cu and Sc co-doped MCN films. • The optical and low-frequency noise properties of Cu and Sc Co-doped MCN films were studied for the first time. • This study provides an insight to understand the effects of Cu and Sc co-dopants on Mn 1.5 Co 1 Ni 0.5 O 4 thin films, which has great significance for preparing high-performance uncooled infrared detectors based on MCN films. [ABSTRACT FROM AUTHOR]