Himansu S. Pattanaik

Design considerations for surface plasmon resonance based detection of human blood group in near infrared

Surface plasmon resonance based sensor for detection of different human blood groups in near infrared region is proposed. The plasmonic structure is based on fused silica or chalcogenide sulfide glass Ge20Ga5Sb10S65, commonly known as 2S2G. Experimental results describing the wavelength-dependent refractive index variation in multiple samples of different blood groups are considered for theoretical calculations. The angular interrogation method is considered. The sensor’s performance is closely analyzed in terms of its angular shift and curve width in order to predict the design consideration for simple and accurate blood-group identifier. The results are explained in terms of light coupling and plasmon resonance condition. Chalcogenide glass-based SPR structure is able to provide highly precise detection of different blood groups. The proposed low-volume blood sensor can be very useful for simple and reliable blood sample detection in medical application.Surface plasmon resonance based sensor for detection of different human blood groups in near infrared region is proposed. The plasmonic structure is based on fused silica or chalcogenide sulfide glass Ge20Ga5Sb10S65, commonly known as 2S2G. Experimental results describing the wavelength-dependent refractive index variation in multiple samples of different blood groups are considered for theoretical calculations. The angular interrogation method is considered. The sensor’s performance is closely analyzed in terms of its angular shift and curve width in order to predict the design consideration for simple and accurate blood-group identifier. The results are explained in terms of light coupling and plasmon resonance condition. Chalcogenide glass-based SPR structure is able to provide highly precise detection of different blood groups. The proposed low-volume blood sensor can be very useful for simple and reliable blood sample detection in medical application.

Design considerations for surface plasmon resonance-based fiber-optic detection of human blood group

A fiber-optic surface plasmon resonance (SPR) sensor for the detection of human blood groups is proposed. Previous experimental results describing the wavelength-dependent refractive index variation of multiple samples of different blood groups are considered for theoretical calculations. The spectral interrogation method, along with silica fiber and silver layer, is considered. The sensors performance is closely analyzed in terms of shift in SPR wavelength and SPR curve width in order to optimize the design parameters for a reliable and accurate blood-group identifier. The sensor design parameters include silver layer thickness, fiber core diameter, sensing region length, and temperature variation. The results are explained in terms of light coupling and plasmon resonance condition. The proposed sensing probe is able to provide high sensitivity and accuracy of blood-group detection, thereby opening an easy and reliable window for medical applications.

On the temperature sensing capability of a fibre optic SPR mechanism based on bimetallic alloy nanoparticles

In this work, we have investigated the capability of different bimetallic nanoparticle alloy combinations to be used in fibre optic temperature sensing based on the technique of surface plasmon resonance (SPR). The metals considered for the present analysis are silver, gold and aluminium. The analysis is derived mainly from the thermo-optic effect along with some fundamental concepts of metal optics such as surface scattering, phonon–electron scattering and electron–electron scattering. The performance of the sensor with three different bimetallic nanoparticle alloy combinations is evaluated and compared, numerically, in terms of its sensitivity and accuracy. On the basis of the comparison and some logistic criterion, we predict the best possible bimetallic alloy combination along with a requisite alloy composition ratio that simultaneously provides higher values of both sensitivity and accuracy which is not possible with any single metallic nanoparticle layer.

Three-dimensional IR imaging with uncooled GaN photodiodes using nondegenerate two-photon absorption

We utilize the recently demonstrated orders of magnitude enhancement of extremely nondegenerate two-photon absorption in direct-gap semiconductor photodiodes to perform scanned imaging of three-dimensional (3D) structures using IR femtosecond illumination pulses (1.6 µm and 4.93 µm) gated on the GaN detector by sub-gap, femtosecond pulses. While transverse resolution is limited by the usual imaging criteria, the longitudinal or depth resolution can be less than a wavelength, dependent on the pulsewidths in this nonlinear interaction within the detector element. The imaging system can accommodate a wide range of wavelengths in the mid-IR and near-IR without the need to modify the detection and imaging systems.

Enhancement of Two-Photon Absorption in Quantum Wells for Extremely Nondegenerate Photon Pairs

We recently demonstrated orders of magnitude enhancement of two-photon absorption (2PA) in direct gap semiconductors due to intermediate state resonance enhancement for photons of very different energies. It can be expected that further enhancement of nondegenerate 2PA will be observed in quantum wells (QWs), since the intraband matrix elements do not vanish near the band center, as they do in the bulk, and the density of states in QWs is larger near the band edge. Here, we present a perturbation-theory-based theoretical description of nondegenerate 2PA in semiconductor QWs, where both the frequency and the polarization of two incident waves can vary independently. Analytical expressions for all possible permutations of frequencies and polarizations have been obtained, and the results are compared with the degenerate 2PA in QWs along with the degenerate 2PA and the nondegenerate 2PA in bulk semiconductors. We show that using QWs in place of bulk semiconductors with both the beams in the transverse magnetic-polarized mode leads to an additional order of magnitude increase in the nondegenerate 2PA. Explicit calculations for GaAs QWs are presented.

Nondegenerate two- and three-photon nonlinearities in semiconductors

Two-photon absorption, 2PA, in semiconductors is enhanced by two orders of magnitude due to intermediate-state resonance enhancement, ISRE, for very nondegenerate (ND) photon energies. Associated with this enhancement in loss is enhancement of the nonlinear refractive index, n2. Even larger enhancement of three-photon absorption is calculated and observed. These large nonlinearities have implications for applications including ND two-photon gain and twophoton semiconductor lasers. Calculations for enhancement of ND-2PA in quantum wells is also presented showing another order of magnitude increase in 2PA. Potential devices include room temperature gated infrared detectors for LIDAR and all-optical switches.

Scanning 3-D IR Imaging With a GaN Photodiode Using Nondegenerate Two-photon Absorption

We demonstrate scanning 3-D IR imaging using non-degenerate two-photon absorption (2PA) in an uncooled GaN photodetector. The SNR of the technique should improve for longer imaging wavelengths due to increased nondegeneracy, which enhances 2PA.

IR detection in wide-gap semiconductors using extreme nondegenerate two-photon absorption

We compare GaAs and GaN for IR detection using extremely non-degenerate two-photon absorption. While the small gap material has larger ND-2PA and hence better sensitivity to IR, unwanted background from degenerate 2PA outweighs this advantage.

Extremely nondegenerate two-photon processes in semiconductors

Direct-gap semiconductors show enhanced two-photon absorption and nonlinear refraction for the extremely non-degenerate case, i.e. for two light waves of very different wavelength, as compared to the degenerate case. We have verified this through measurements of non-degenerate two-photon absorption and nonlinear refraction in several direct-gap semiconductors. We have demonstrated application towards mid-infrared detection and imaging, as well as 2-photon gain in the mid infrared. We also show how semiconductor quantum wells may be employed to engineer even larger enhancements of these effects.

Nondegenerate nonlinear refraction, absorption, and gain in semiconductors (Conference Presentation)

We have shown both experimentally and theoretically that the effect of intermediate-state resonance enhancement causes highly nondegenerate 2-photon absorption, 2PA, to be strongly enhanced in direct-gap semiconductors. Calculations indicate an additional 10x increase in this enhancement is possible for quantum-well semiconductors. This enhancement leads to interesting applications of 2PA, such as mid-infrared detection, where uncooled, large-gap photodiodes can rival the sensitivity of cooled MCT detectors (for short pulses). Additionally, mid-IR imaging and tomography based on this effect have been shown. Even larger enhancement of 3PA is calculated and observed. In the case of optically-pumped semiconductors, we have now demonstrated that the complementary process of nondegenerate 2-photon stimulated emission can be observed. Theoretically, this results in 2-photon gain (2PG) that is enhanced as much as 2PA, leading to the possibility of large gap devices with tunable mid-infrared gain. However, the effect of nondegenerate enhancement of 3PA can be detrimental to the observation of this gain. Additionally, by causality, Kramers-Kronig relations predict that the enhancement of 2PA is accompanied by an enhancement of the nonlinear refractive index, n2, which is very highly dispersive in the region of 2PA. Our latest experimental results confirm this enhancement and strong dispersion.