Since the first commercial silicon transistor in 1954, the integration of large numbers of transistors into a small chip has led to the explosive growth of the electronics integrated circuits and the ability of microelectronics to constantly renew industrial developments across many sectors. Photonics, where light is used to provide functionality, is currently experiencing a similar trend pushing to develop technologies that are supporting migration from larger optical systems to chip-level complex functionality.
Unlike electronic chips where everything is centered on the scalability of a single type of component, the transistor, photonic chips have to integrate a large variety of components, such as lasers, detectors, modulators and filters.To this end, photonics chips based on silicon take the advantage of well-established silicon electronics processes and materials. For example, optical waveguides can be made of silicon or related material like silicon-nitride and surrounded by silicon dioxide.
Even though the silicon photonics circuits are industrially scalable they still suffer a big drawback: silicon is a poor material to emit light and therefore, light-emitting devices have to be fabricated using III-V semiconductors. Then III-V semiconductor light emitters have to be integrated using specialized hybrid processes with silicon photonics circuits.
In his doctoral research Nouman Zia worked on integrating III-V semiconductor alloys with Silicon Photonics Circuits to develop a wavelength-versatile integrated-light-source platform with advanced functionality for sensing applications at mid-IR wavelengths (≥ 2 µm).
“The need for integrated light sources is fueled by the high demand for compact sensors in the detection of gases and medical diagnostics. Such light sources can be tailored to address other applications in the field of quantum photonics, and 3D sensing, yet each application operates at a different wavelength. This makes the wavelength-versatility a very desirable feature,” Nouman Zia says.
Zia’s research focused on developing two main elements of chip-scale light sources: i) GaSb-based III-V semiconductor chips for broadband light emission, ii) photonics integrated circuits for adding the dynamic wavelength selection functionality.
“The chip-scale light sources are very robust since III-V chips and silicon photonics circuits are optimized and manufactured separately for state-of-the-art performance,” he explains.
The doctoral dissertation of M.Sc. Nouman Zia in the field of photonics titled Wavelength-versatile GaSb light emitters for hybrid photonics integrated circuits will be publicly examined in the Faculty of Engineering and Natural Sciences at Tampere University on Friday 16th December 2022 at 13:00 at Hervanta Campus, in Tietotalo auditorium TB109 (Korkeakoulunkatu 1, Tampere). The Opponent will be Professor Michael Wale from the University College London (United Kingdom) and the Eindhoven University of Technology (Netherlands). The Custos will be Professor Mircea Guina from the Optoelectronics Research Centre, Faculty of Engineering and Natural Sciences, Tampere University.
Photo: Prabudeva Ramu