• SURINDER SINGH

      Articles written in Bulletin of Materials Science

    • Effect of optical parameters on design of highly reflecting distributed Bragg reflectors based on compound semiconductors for space applications

      RAHUL K SHARMA SUDIPTO DAS GUPTA H S JATANA SURINDER SINGH

      More Details Abstract Fulltext PDF

      Comprehensive model for the design of highly reflecting distributed Bragg reflectors (DBRs) is investigated for spectral band, ranging from ultraviolet to short wavelength infrared (SWIR). The reflectivity calculation is done using thin film multiple reflection technique. The variation of reflectivity as a function of wavelength, number of grown epilayers, angle of incidence and difference between refractive indices of constituent epilayers is examined. The target wavelengths for reflectivity simulation include 1.55 and 1.3 $\mu$m for optical communication, 850 and 980 nm for infrared (IR) imaging devices and chip-scale atomic clocks, and 412 and 443 nm for UV light emitting diodes and antireflection coatings for charge-coupled devices and solar cells. The reflectivity values calculated for compound semiconductor DBRs lie between 95 and 99%. It is also inferred that the reflectivity of grown epilayers and broadness of operational spectrum increases with number of epilayers. If DBR stack is grown on lattice mismatched substrate, increment of the reflectivity is found only at single wavelength. As the angle of incidence increases from 0$^{\circ}$to80$^{\circ}$,blue shift in reflectance (towards low wavelength) is also observed. The increase in reflectivity is also observed with increase in difference in refractive indices of epilayers.

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