Polarization engineered InGaN/GaN Visible-light photodiodes featuring high responsivity, bandpass response, and high speed

Optoelectronic devices, especially III-nitride quantum-structure devices, are suffering from a serise of material problems, such as polarization induced quantum efficiency drooping and lack of suitable p-type dopant. Herein, dopant-free polarization-induced...

Внутридопплеровские резонансы затухания свободной поляризации в ультратонких газовых ячейках

The linear-optical effect of the free polarization decay (FPD) in an ultrathin gas cell, the internal thickness of which is less than or of the order of the wavelength of the exciting monochromatic laser radiation, transmitted orthogonally to the plane-parallel walls of this cell, is theoretically investigated. The considered coherent FPD signal is emitted immediately after an abrupt interruption of such a relatively weak stationary radiation. Sub-Doppler resonances arising at the central frequencies of the studied quantum transitions in the spectra of the intensity and energy of the FPD as a result of the transit-time relaxation of atoms in the gas cell are established and analyzed. A significant dependence of these resonances and the dynamics of the FPD on the ratio of the inner thickness of the ultrathin cell to the wavelength of the exciting monochromatic radiation is shown. The narrow, high-contrast sub-Doppler resonances of the FPD detected and investigated in the linear-optical regime can be used in ultrahigh-resolution atomic (molecular) spectroscopy, as well as references for compact frequency standards.

Zero-bias mid-infrared graphene photodetectors with bulk photoresponse and calibration-free polarization detection

Bulk photovoltaic effect (BPVE), featuring polarization-dependent uniform photoresponse at zero external bias, holds potential for exceeding the Shockley-Queisser limit in the efficiency of existing opto-electronic devices. However, the implementation of BPVE has been limited to the naturally existing materials with broken inversion symmetry, such as ferroelectrics, which suffer low efficiencies. Here, we propose metasurface-mediated graphene photodetectors with cascaded polarization-sensitive photoresponse under uniform illumination, mimicking an artificial BPVE. With the assistance of non-centrosymmetric metallic nanoantennas, the hot photocarriers in graphene gain a momentum upon their excitation and form a shift current which is nonlocal and directional. Thereafter, we demonstrate zero-bias uncooled mid-infrared photodetectors with three orders higher responsivity than conventional BPVE and a noise equivalent power of 0.12 nW Hz−1/2. Besides, we observe a vectorial photoresponse which allows us to detect the polarization angle of incident light with a single device. Our strategy opens up alternative possibilities for scalable, low-cost, multifunctional infrared photodetectors.