A. Abramovich

Inexpensive detector for terahertz imaging

Glow discharge plasma, derived from direct-current gas breakdown, is investigated in order to realize an inexpensive terahertz (THz) room-temperature detector. Preliminary results for THz radiation show that glow discharge indicator lamps as room-temperature detectors yield good responsivity and noise-equivalent power. Development of a focal plane array (FPA) using such devices as detectors is advantageous since the cost of a glow discharge detector is approximately

Terahertz detection mechanism of inexpensive sensitive glow discharge detectors

0.2-

Inexpensive THz Focal Plane Array Imaging Using Miniature Neon Indicator Lamps as Detectors

0.5 per lamp, and the FPA images will be diffraction limited. The detection mechanism of the glow discharge detector is found to be the enhanced diffusion current, which causes the glow discharge detector bias current to decrease when exposed to THz radiation.

THz Polarization Effects on Detection Responsivity of Glow Discharge Detectors (GDDs)

The detection mechanism of glow discharge plasma, which is derived from direct current gas breakdown, in neon indicator lamps was investigated in the terahertz and microwave regimes. Such devices exhibit high sensitivity to terahertz radiation. Experimental setups at 10, 100, and 250GHz were carried out and analyzed. The analysis of the experimental results shows that the dominant mechanism of the glow discharge detector (GDD) in these regimes is enhanced cascade ionization. Furthermore, the responsivity at 10GHz decreases with the increase in the dc bias current between the electrodes, while the responsivity at 100 and 250GHz increases with the dc current. This is attributed to electron-neutral atom collision frequency (ν) of the GDD being tens of gigahertz and its increasing with dc bias current according to dc field increase.

Design of inexpensive diffraction limited focal plane arrays for millimeter wavelength and terahertz radiation using glow discharge detector pixels

Development of focal plane arrays (FPAs) for mm wavelength and THz radiation is presented in this paper. The FPA is based upon inexpensive neon indicator lamp Glow Discharge Detectors (GDDs) that serve as pixels in the FPA. It was shown in previous investigations that inexpensive neon indicator lamp GDDs are quite sensitive to mm wavelength and THz radiation. The diameters of GDD lamps are typically 3-6 mm and thus the FPA can be diffraction limited. Development of an FPA using such devices as detectors is advantageous since the costs of such a lamp is around 30-50 cents per lamp, and it is a room temperature detector sufficiently fast for video frame rates. Recently, a new 8 × 8 GDD FPA VLSI control board was designed, constructed, and experimentally tested. First, THz images using this GDD FPA are given in this paper. By moving around the 8 × 8 pixel board appropriately in the image plane, 32 × 32 pixel images are also obtained and shown here, with much improved image quality because of much reduced pixelization distortion.

Efficiency enhancement of free electron Maser oscillator by mode selection with a prebunched electron beam

The detection mechanism of glow discharge plasma in neon indicator lamps has been investigated in the terahertz and microwave spectral regions. The influence of the THz radiation polarization on the responsivity of glow discharge detectors (GDD) is considered here. There are two detection mechanisms in the GDD that exist simultaneously, each at the expense of the other. Experiments with GDD neon indicator lamps in the THz regime prove that the dominant detection mechanism of the GDD is enhanced cascade ionization rather than enhanced diffusion current. Our polarization experiments in the THz regime show that when the electric field of the THz radiation is in the same direction as the DC bias electric field of the lamp, the responsivity is about 50% higher than when the THz electric field is orthogonal to the DC field. This supports the concept that the dominant detection mechanism of the GDD in the THz regime is enhanced cascade ionization.

Heterodyne Detection by Miniature Neon Indicator Lamp Glow Discharge Detectors

Development of focal plane arrays (FPAs) for millimeter wavelength and terahertz radiation is presented in this paper. FPA is based on an inexpensive glow discharge detector (GDD) that serves as a pixel in the FPA. It was shown in previous investigations [A. Abramovich et al., Appl. Opt. 46, 7207 (2007)] that those inexpensive neon indicator lamp GDDs are quite sensitive to millimeter wavelength and terahertz radiation. The diameter of the GDD lamp is 6 mm and thus the FPA can be diffraction limited. Development of a FPA using such devices as detectors is advantageous since the cost of such lamps is around

W-Band Chirp Radar Mock-Up Using a Glow Discharge Detector

0.2–0.5 per lamp, and it also serves as a room temperature detector. Experimental results at 100 GHz show that the responsivity of the terahertz FPA 4×4 GDD pixel is three times better than in previous measurements of A. Abramovich et al. [Appl. Opt. 46, 7207 (2007)].The addition of a parabolic reflector improves the accuracy of the noise equivalent power measurement which was found to be 6×10−9 W/√Hz ...

Effect of 99 GHz continuous millimeter wave electro-magnetic radiation on E. coli viability and metabolic activity

We present a method for enhancing the efficiency of a Free Electron Laser Maser oscillator by locking it to a preferred resonator mode. This is done by prebunching of the e beam before injection into the wiggler. In a free running oscillator, the longitudinal mode that dominates the mode competition process during the oscillation buildup period is usually the highest gain mode. However, this mode does not extract the highest energy from the e beam. Lower eigenfrequency modes would provide a higher efficiency if they could dominate the mode competition process. By prebunching the e beam at a frequency near any one of the longitudinal eigenfrequencies of the resonator (having a gain>1), we can make that mode dominant at saturation. The eigenfrequency for which the maximum efficiency is obtained is the lowest eigenfrequency of the resonator for which the net small signal gain is greater than 1. Employing an experimental setup of a prebunched beam Free Electron Maser, we demonstrated efficiency enhancement of...

The TeraMOS sensor for monolithic passive THz imagers

Miniature neon indicator lamps acting as glow discharge detectors (GDD) are candidates to serve as very inexpensive room-temperature Terahertz radiation detectors and as pixels in THz imaging systems. Previous experiments with GDD devices with THz waves showed good responsivity and noise equivalent power using direct detection. Significant improvement of detection performance is expected using heterodyne detection. Since THz sources are expensive and heterodyne detection requires two sources, we show here a proof of concept at low frequencies. In this paper, we compare the performance of GDDs in direct detection to the performance of GDDs in heterodyne detection at 10 GHz. The experimental results show that heterodyne detection is almost two orders of magnitude more sensitive than direct detection, and that in general sensitivity is inversely proportional to increasing local oscillator power. Heterodyne detection at 300 GHz is also demonstrated.