Akil Ahmed

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Quantum Cascade Laser (QCL) is extremely unique in its characteristics due to its narrow bandwidth resulting from unipolar operation, mid-infrared emission, and wavelength tunability by quantum mechanical engineering. While lasing, the change in temperature affects the cavity length of the QCL, which in turn may affect the emission wavelength. In this work,(More)
Design of a novel selective band delay element and its performance gain over nominal low pass LC ladder based delay element is demonstrated. The delay element uses three 2<sup>nd</sup> order all pass filter as its core element and achieves a delay of 200 &#x00B1; 10 ps within 6.8 GHz to 12.9 GHz range. The circuit is implemented using 130 nm RF CMOS(More)
The electroluminescence linewidth is a significant performance indicator of quantum cascade lasers (QCLs) as it determines peak gain, degree of monochromaticity, and wavelength tunability. In this work, we have modeled the intersubband electroluminescence linewidth of QCLs considering the intersubband and intrasubband electron-LO phonon scattering and(More)
Quantum cascade lasers (QCLs) are the most promising light sources for optical spectroscopy in the molecular finger-print mid-infrared region. To this purpose, QCLs are required to be wavelength selective and the change of emission wavelength needs to be known beforehand as the operating conditions, such as the applied bias changes. In this paper, we study(More)
Since the first ever demonstration of the quantum cascade lasers (QCLs) in 1994, there has been extensive research on its improvement for various reasons. One of them is to produce ultrashort optical pulses. The nonlinearity in the index of refraction of a lasing medium can be manipulated to produce ultrashort laser pulses which have applications in the(More)
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