• Ultrafast nonlinear optical responses and transient gratings are studied across semiconductor-doped glasses and quantum-confined structures, revealing femtosecond bleaching, picosecond relaxation, and room-temperature excitonic nonlinearities in CdSSe glasses, CdS nanocrystals, CdSe QDs, and GaAs/GaAlAs MQWs [1], [4], [15], [6], [17], [18], [11].

• Telecom-band (1.54 μm) luminescence and electroluminescence arise from Er3+ implanted/doped semiconductors, with oxygen impurities enabling optical activation in silicon, highlighting impurity engineering as a route to infrared light sources [2], [3], [8].

• Infrared photodetectors and IR-active architectures use quantum wells, superlattices, and intersubband transitions to achieve enhanced detection and spectral response, as demonstrated in GaAs QWIPs, GaAs/AlGaAs superlattices, and SiGe/Si MQWs [9], [14], [13].

• Quantum confinement in CdS/CdSe nanostructures and nanoporous silicon yields size-tunable absorption and emission, with ultrafast phenomena and nonlinearities [7], [16], [17], [6].

• Processing, impurities, and defect engineering modulate optical/electronic properties across diverse materials—from amorphous Si and ITO to oxide films—reconfiguring conductivity, band gaps, and luminescence via light or heat treatments [20], [19], [10].