UA148155U - METHOD OF RESONANCE REGISTRATION IN PLASMON-POLYARITON PHOTODETECTORS - Google Patents

Abstract

The method of recording resonance in plasmon-polariton photodetectors (PPFD) is to measure the spectral or angular dependence of the photocurrent in the vicinity of plasmon-polariton resonance and its normalization (division) on the light intensity of PPFD using a microcontroller containing an analog or other converter digital device with a reference channel. To reflect the light intensity of PPFD, light reflected from the surface of PPFD is used.

Description

The useful model belongs to the methods of recording plasmon-polariton resonance (PPR) in optoelectronic devices built on the basis of the phenomenon of surface plasmon-polariton wave (SPR) excitation. The proposed method of detecting resonance can be used in the construction of sensors based on plasmon-polariton photodetectors (PPFD) for industry, medicine, and environmental protection.

The closest analogue of a useful model is the method of detecting resonance in polarization-sensitive PPFDs based on the Schottky barrier (US patent Mo 103379, 501М 21/55), which consists of a surface-barrier heterostructure, namely a semiconductor substrate on which a layer is applied of a metal with a periodically profiled metal/air interface in the form of a diffraction grating, which is characterized by the fact that the semiconductor substrate is flat, and a multilayer structure based on a metal layer and chalcogenide nanowires is used to form a periodically profiled topography at the metal/air interface semiconductor, which has an anticorrelated topography when the profiles of the metal/semiconductor and metal/air interfaces are shifted by half a period, so its thickness is a periodic function of the planar coordinate with a period equal to the period of the diffraction grating. With the help of PPFD in the visible spectral range (0.5-0.8 μm), an increase in the sensitivity of detection of environmental parameters is achieved while maintaining the simplicity of the design, small dimensions and low material and energy costs, which, in addition, combines in one element as an excitation PPP, as well as registration of the output signal.

At the same time, the PPFD measures the photocurrent, which is normalized to the value of the incident light intensity measured by an independent calibrated photodetector. This is a standard scheme for measuring the photosensitivity of any photodetectors.

The advantages of such a scheme include simplicity and reliability. The disadvantages include the method of organization of measurements, when before measuring the signal from the PPFD, a calibrated photodetector must be placed in the same place and in the same channel. That is, the measurements are spaced in time, during which the intensity of radiation from the source can change. Therefore, an error will be introduced into the measurements, which imposes, in particular, special requirements on the stability of the power source of the illuminator.

This applied to the case of a single-channel measurement scheme.

In the case of a two-channel scheme, where the measurements will be simultaneous, a technical organization 0) of the second channel is required, with beam splitting from the illuminator, which complicates and makes the measurement scheme more expensive.

Thus, there is a need for a simplified method of recording the signal from the PPFD, simultaneous measurement of the signal from the PPFD and a calibrated photodetector for measuring the intensity of illumination falling on the PPFD. At the same time, it is not desirable to complicate the scheme by organizing an additional channel with splitting the light beam.

The task is solved by the PPFD method, which consists in measuring the spectral or angular dependence of the photocurrent in the vicinity of the plasmon-polariton resonance and its normalization (division) by the intensity of illumination of the plasmon-polariton photodetectors with the help of a microcontroller containing an analog-to-digital converter, or other analog or digital device with a reference channel, according to a useful model, to measure the illumination intensity of the PPFD uses light reflected from the surface of the PPFD, and not the light (or part thereof) directly from the illuminator. At the same time, the reference signal of the PPFD illumination is fed to the reference channel of the analog-to-digital converter of the microcontroller or other analog or digital device for signal processing. The analog-to-digital converter divides the photocurrent signal from the PPFD into the photocurrent signal of the reference photodetector and outputs a digital code for processing in the microcontroller. The result of dividing the intensity of the photocurrent signal by the reference signal increases as a result of an increase in the photocurrent under conditions of excitation of plasmon-polariton resonance, and as a result of a decrease in the reference signal of the intensity of light reflected from the PPFD surface under conditions of plasmon-polariton resonance. The result of this resonance measurement method is proportional to the square of the intensity of the resonance value when measured under standard conditions, when the reference light intensity is obtained directly from the PPFD illuminator. This significantly increases the intensity of the signal in resonance while reducing its half-width, which is important when using such PPFDs as the basis for building sensors for various purposes.

Fi. 1 - shows a schematic representation of a plasmon-polariton resonance recording scheme, in which a laser radiation source (1) is used, which is directed (2) to the surface of a plasmon-polariton structure (3), which is a plasmon-polariton photodetector (4), and a conventional photodetector (5), which receives reflected radiation from a plasmon-polariton photodetector.

Fig. 2 - spectral dependences of the photocurrent (signal) on the absorbed radiation of the reference photodetector (curve 6), the plasmon-polariton photodetector in p- (curve 7) and 5- polarization (curve 8, provided there is no resonance).

Fig. C - spectral dependences of the photocurrent (signal) from the plasmon-polariton photodetector in p-polarization (curve 7) (output signal), the resulting photocurrent (curve 9), which is obtained by dividing the p-polarization signal (curve 7) by the signal from the reference photodetector ( Fig. 2, curve 6) and the resulting photocurrent (curve 10), which is the result of scaling the p-polarization signal (curve 7) (relative factor 1.8), which is done for the convenience of comparing the curves with each other. The intensity increased by 1.8 times, and the half-width decreased from 120 nm to 90 nm (by 1.33 times).

Fig. 4 - an example of the electrical schematic diagram of the recording device, which includes a conventional photodetector 01, a plasmon-polariton photodetector 02, feedback resistors КИ and К2 with operational amplifiers and an ATMESAV8 microprocessor.

A useful model uses a plasmon-polariton photodetector of Fig. 1. (4), in which the excitation of plasmon-polariton resonance depends on the characteristics of the barrier photosensitive structure (3), on the angle of incidence of laser radiation and on its wavelength. The last two parameters are normalized to ensure the correct operation of the detection device. The photodetectors (4-5) are connected to a microprocessor, which digitizes and divides the received signal intensities from the photodetectors, due to which the dependence on the stability of the PPFD illumination level disappears. A significant increase in the detection ability occurs at the plasmon-polariton resonance of structure (3), in which the reflection from the surface decreases and the penetration and absorption of radiation in it increases. As a result, the signal from the reference channel is significantly reduced due to a decrease in the intensity of the incident radiation on the photodetector (5), the signal from the photodetector (4) is significantly increased, and due to computational transformations in the microprocessor, in which the input signal of the photodetector (4) is divided into the reference the signal of the photodetector (5), the recording capacity increases several times, which characterizes the high sensitivity of the detection method using the registration of plasmon-polariton resonance on the plasmon-polariton photodetector.

The positive effect of the proposed useful model consists in increasing the sensitivity of detection due to the registration of plasmon-polariton resonance on the plasmon-polariton photodetector.

Sources of information: 1. Pat. 103379 Ukraine, IPC (2006) С01М 21/55. Polarization-sensitive plasmon-polariton photodetector based on the Schottky barrier / M.L. Dmytruk, S.V. Mamikin, M.V.

Sosnova, O.V. Korovin, V.I. Minko, 3.I. Kazantseva; Application 01.11.2011; Publ. 10.10.2013, Bull.

Mo 19.

Claims (3)

USEFUL MODEL FORMULA 1. The method of registration of resonance in plasmon-polariton photodetectors (PPFD), which consists in measuring the spectral or angular dependence of the photocurrent in the vicinity of the plasmon-polariton resonance and its normalization (dividing) by the intensity of illumination of the PPFD with the help of a microcontroller containing an analog-to-digital converter, or other analog or digital device with a reference channel, which differs in that light reflected from the surface of the PPFD is used to measure the illumination intensity of the PPFD. 2. The method of registering resonance in the PPFD according to claim 1, which differs in that the photocurrent signal from the reference photodetector, which registers the light reflected from the PPFD, is fed to the reference channel of the analog-to-digital converter of a microcontroller or other analog or digital signal processing device. 3. The method of registering resonance in the PPFD according to claim 1, which differs in that the analog-to-digital converter performs the process of dividing the photocurrent signal from the PPFD into the photocurrent signal of the reference photodetector and outputs a digital code for processing in the microcontroller.