(CdSe)ZnS Core−Shell Quantum Dots: Synthesis and Characterization of a Size Series of Highly Luminescent Nanocrystallites

Spectroscopic and luminescence properties of Ho3+ ions doped Barium Lead Alumino Fluoro Borate glasses for green laser applications

Selectivity is one of the most crucial figures of merit in trace gas sensing, and thus a comprehensive assessment is necessary to have a clear picture of sensitivity, selectivity, and their interrelations in terms of quantitative and qualitative views. Recent reviews on gas sensors/techniques are limited to specific sensors, sensors with unconventional materials, various technological exploitation, or specific applications. However, the selectivity is either unexplored in most cases or explained concerning the materials/techniques involved in a demonstration. Therefore, there is a pressing need to identify the possible ways to improve the selectivity of a gas sensor/technique with low or zero cross-sensitivity to other compounds/gases present in the working environment. Analytical techniques involving spectroscopic and mass-spectrometry-based methods are excellent in selectivity but have limited applicability for field deployment compared to the miniatured solid state sensors. Solid state sensors are the mainly studied gas sensors due to their flexibility, portability, and cost-effectiveness, and being technologically favorable but suffer from low selectivity in harsh and humid environments. This review will evaluate the limitations and possible solutions to selectivity issues in a wide variety of gas sensors. Here, we have discussed the gas-sensor technologies and underlying sensing mechanisms in two main groups - spectroscopic and non-spectroscopic. Recent state-of-the-art techniques and fundamental challenges are discussed to improve the selectivity and other gas sensor indicators and future perspectives.

Selectivity in trace gas sensing: recent developments, challenges, and future perspectives.

An approach to design photonic crystal gas sensor using machine learning

Artificial intelligence approach for calculating electronic and optical properties of nanocomposites

In this paper, 1D Photonic Crystal structure, consisting of alternate layers of silicon and air, is theoretically studied for gas sensing application. With one of the air layers replaced by a different gas layer, the resulting defect mode can be utilized for sensing a particular gas, from the transmittance curve, calculated by Transfer matrix method. Very small refractive index variation, ∆n = 1.5 × 10−5 and a sensitivity = 979 nm/RIU is found by this sensor.

Photonic Crystal for Gas Sensing Application

Enhancement of optical gain in quantum dot ensemble with electric field

In this paper, the effect of Quantum Dot size, deviation of dot size, carrier concentration etc. on the absorption coefficient, emission coefficient and material gain of GaAs/AlGaAs Quantum Dot ensemble are studied. It has been assumed that the distribution of the density of state is Gaussian in nature due to the deviation of the dot size. The absorption coefficient is calculated using Fermi's golden rule. The study shows that the distribution of density of states results in the broadening of the spectrum which may be useful for broadband applications like sub-cellular tissue imaging in medical system.

Study the effect of inhomogeneous broadening in Quantum Dots for application in medical imaging

In this paper, the electron energy and intersubband absorption coefficient are calculated for a spherical core shell quantum dot structure. Considering the variation of dot size over a layer and scattering mechanisms, Gaussian distribution in density of state is used in the analysis. Both the transition energy and the peak absorption coefficient decrease with core radius.

Intersubband absorption in core shell quantum dot

In this paper, the effect of external electric field on the absorption coefficient, emission coefficient and material gain of Quantum Dot ensemble are studied using Fermi's golden rule and considering the Gaussian distribution of density of state due to the deviation of the dot size. The study shows that the electric field causes red-shift in optical transition as well as enhanced optical gain.

Shampa Guin

Papers

Photonic Crystal for Gas Sensing Application

Enhancement of optical gain in quantum dot ensemble with electric field

Study the effect of inhomogeneous broadening in Quantum Dots for application in medical imaging

Intersubband absorption in core shell quantum dot

Electric field aided optical gain in semiconductor quantum dots