Temperature tunability of surface plasmon enhanced Smith-Purcell terahertz radiation for semiconductor-based grating

Abstract

Strong demand of terahertz (THz) applications has attracted great attention in the development of compact and tunable light source. Especially, high-efficiency generation of THz light source is one of the most important issues and still remains to be overcome for the field of imaging and diagnostics 1, 2 . As an electron beam moves over a metallic surface, the surface plasmon (SP) on the surface can be excited. Subsequently, SP can be transformed into radiation modes by the designed structures such as slits, grooves and periodic gratings on the surface [3][4][5][6] . However, only the SPs whose operating frequencies close to the intrinsic plasma frequency of the metal can be efficiently excited. Hence the radiation frequencies are limited in optical and ultraviolet regions for most used noble metal 7 . An electron beam passing over a metallic grating can also generate Smith-Purcell radiation (SPR). This type of radiation comes from the oscillation of charges and imaged charges on the grating which induces the periodically changing current density on the grating [8][9][10][11][12] . The emission frequency of SPR ranges from microwave to visible depending on the grating period and the electron velocity. Very recently, SPR that are manipulated by excitation of SPs and mimimic-SPs has been proposed and demonstrated 9,10,[12][13][14] . Especially, ref. 10 investigates the condition that both the frequencies of SP and mimic-SP are out of the radiation band of SPR. The SPR is not enhanced and the radiations from SPR, SP and mimic-SP are all observed. References 13 and 14 propose and demonstrate amplification and manipulation of SPR by excitation of SPs on Ag film. And in refs 9 and 12, the generation of enhanced coherent THz SPR by excitation of mimic-SPs are proposed and explored.The indium antimonide (InSb)-dielectric interface can also support propagation of SPs under illumination of terahertz light source 15 . The optical property of InSb at THz region is similar to that of noble metals in the optical region [16][17][18] . Furthermore, the optical properties of InSb can be tailored by changing its temperature 19 , by applying external magnetic field on it 20 and by doping impurity into it 21 . Recently, many InSb-based tunable optoelectronic components based on controlling their temperatures have been studied, such as tunable photonic crystals 19 , infrared photo-detectors 22 , thermally controlled metamaterial [23][24][25][26] , data storage 27 , and subwavelength

Performance-Enhanced Polysilicon Microbolometer in CMOS Technology With a Grating Structure

“…However, it is difficult for incident light to excite the surface plasmons in many cases because the kin is smaller than surface plasmons. To solve the problem, the grating structures are used to adjust the kin through the following Equation [30,31]:…”

Thermally tunable Dyakonov surface waves in semiconductor nanowire metamaterials

“…The distinct features of InSb such as the small band gap, low effective mass, high electron mobility and highly temperature-dependent carrier density, make its permittivity easily influenced by a small change in temperature. In the THz frequencies, the complex-valued relative permittivity of InSb is obtained by the Drude model 40 where is the high frequency dielectric constant, is the resonant frequency, THz is the damping constant and is the plasma frequency, where e is the electron charge, is the effective mass, is the electron mass, is the permittivity of vacuum and N is the carrier density in which depends on temperature, T (in Kelvin) and in InSb is 41 , 42 where is the Boltzmann constant. The variation in T causes the change in N , which subsequently makes the plasma frequency, tunable via changing the temperature.…”

Near-field resonances in photon emission via interaction of electrons with coupled nanoparticles

“…Mathematically, which opens the opportunity to find the solution analytically, is the fact that the Fourier-image of Eq. (7) in variables (q, ω)…”

“…Today we observe the burst of interest in the collective effects in the radiation processes of different nature and in different spectral ranges, from submillimeter (terahertz) to infrared, optical, UV, and x-ray ranges. Local field effects [1][2][3][4][5], including giant enhanced surface phenomena [1,6], excitation of plasmons in surface nanostructures [1,[7][8][9], new applications and ways of realization of the Smith-Purcell effect [5,[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], and many other interesting ideas including the strange, at first glance, ones like search for the new physics with atoms and molecules [23] rather than with collisions of superhighenergy charged particle beams at modern colliders--all these appeal to the attention of researchers all over the world. In a way, it is fair to say that today the interest in collective effects in radiation from complex systems, essentially dependent on the effects of coupling between their constituent elements, takes the lead over the existing theoretical background.…”