The Ge1-xSnx material system has been introduced as a potential solution for low-cost high-performance photodetector for short-wave infrared towards mid-infrared detections. An investigation of GeSn/SiGeSn nanostructure layer is reported for sensors for near and mid-infrared applications. Physics-based models will be developed for SiGeSn/GeSn based nanostructured sensors considering the carrier dynamics at hetero-interface, misfit dislocation and strain at the interface. We analyze the effect of biaxial strain on SiGeSn/GeSn alloys and determine the range of wavelength for the possible application in near and midinfrared range.
This work emphasizes on the comparative study of tin based group IV single and multiple quantum well photodetector in absence of light. Initially, the designs of the single quantum well infrared photodetector (SQWIP) and multiple quantum well infrared photodetector (MQWIP) are proposed and explained along with considerations. Dark current and detectvity is calculated by using rate equations considering carrier transfer mechanism in MQWIP and SQWIP. The result reveals that dark current in the order of microampere is obtained for SQWIP but it can be reduced by increasing number wells. Significant peak detectivity in the range of 109 cm Hz1/2 W-1 is obtained for MQWIP at lower bias which is higher than that of SQWIP. However judicious selection of proper bias and number of well is required for optimized operation of MQWIP.
Space division multiplexing (SDM) technique is proposed to augment performance of short-reach optical transmission systems by utilizing 8-core multicore fiber (MCF) that typically degrades at high data rates for higher order modulation. Intercore crosstalk (XT) and higher order modulation format are the most challenging impairments of SDM based interconnection technology for efficient usage of MCF as OI. To satisfy the capacity requirements of emerging heterogeneous and bandwidth-intensive short reach communication links a frequency interleaving scheme is applied to MCF OI transmission systems. The negative effects of spectral overlap and intercore XT is reduced by shifting channel frequencies between adjacent cores. To combat explosive growth in data volume requirement of next generation highperformance short-reach OIs transmission higher order quadrature phase shift keying (QPSK) modulation in index profiled MCF system is proposed. Digital signal processing such as multiple input multiple output (MIMO) equalization are used to evaluate the symbol error probability in QPSK modulated SDM system.
Space division multiplexing (SDM) technique is proposed to overcome the bandwidth density drives of short-reach optical transmission systems by utilizing 8-core multicore fiber (MCF). Intercore crosstalk (XT) and higher order modulation format are the most challenging impairments of SDM based optical interconnect (OI) systems. To satisfy the exponential growth of the Internet traffic a frequency interleaving scheme is applied to short-reach MCF OI transmission systems. The negative effects of spectral overlap and intercore XT is reduced by shifting channel frequencies between adjacent cores. To exploit the full potential of SDM power efficient binary phase shift keying (BPSK) modulation format and digital signal processing such as multiple input multiple output (MIMO) equalization are used.
This paper focus on the theoretical investigation of quantum confined Stark effect (QCSE) in strain compensated SiGeSn/GeSn single quantum well (QW). Eigen energies in presence of electric field, for Г valley conduction band (Г- CB) and heavy hole band (HH)) are obtained from the self consistent solution of coupled Schrödinger and Poisson equations by finite difference method. Absorption coefficient considering excitonic effect for direct transition of HH band to Г valley is calculated. A significant shift in absorption peak towards longer wavelengths is observed.
Although, the technological breakthroughs such as WDM had allowed the capacity per fiber to be increased around tenfold every four years in the past decade, however, the capacity of the optical communication systems based on these transmission technologies is slowly becoming saturated. To satisfy the exponential growth of the Internet traffic, for the next generation short reach systems, including data center transmission and optical interconnect (OI) applications, the space-division multiplexing (SDM) can be a way forward. The SDM technology based on the multicore fiber (MCF) has recently attracted much attention as a potential approach. In this paper, design strategy of computer-compatible 8-core trench-assisted MCF (TA-MCF) is presented to reduce the intercore crosstalk. Moreover, the influence of butt-coupled TA-MCF OI on coupling loss is also discussed. On the other hand, another alternative approach, the mode division multiplexing (MDM) is also showing promise and mode (de)multiplexer is one of the key devices in such a MDM system. Designs of mode splitters using asymmetric directional couplers for the fundamental quasi-TE (TM) mode with the higher order quasi-TE (TM) modes (de)multiplexer including the Hy21 (Hx21), Hy31(Hx31, Hy41(Hx41, and Hy51(Hx51) modes are optimized by using a full-vectorial H-field finite element method.
The dynamics of a quantum cascade laser (QCL) have been analyzed theoretically using a three level rate equation
model. It is observed that the electric field and the temperature affect the QCL turn-on transients significantly.