Optoelectronics and MOEMs
Optoelectronics and MOEMS Group (earlier, Optoelectronic Devices Group) at CSIR-CEERI Pilani is engaged in design and development of various optoelectronic and photonic devices. In recent years, the group has developed various components/devices like 980-nm pump laser diode for erbium-doped fiber amplifier (EDFA) application, 1×8 optical splitter for fiber to the home (FTTH) network application, GaAs Hall sensors for automotive application and so on. Corrugated long-period waveguide gratings (LPWGs) for integrated-optic band-reject/ band-pass filter and sensing applications has been developed by the group, which is reported for the first time on silica-on-silicon material. Currently, the group is working on GaN-InGaN material based blue light emitting diode (LED) and phosphor-coated white LED devices for solid state lighting (SSL) applications. Epitaxial layer structures required for LEDs have also been grown at CSIR-CEERI by using metal organic chemical vapor deposition (MOCVD) reactor. Following optimization of various unit processes, blue LED devices have been fabricated and tested. Ce-doped YAG yellow phosphor is used to achieve white light from blue emission. Devices are packaged with ceramic heat-sink and plastic lens. Solar-powered lamp has been designed and developed in association with CEERI-Chennai Centre using an array of these indigenous LEDs with a target to achieve multi-LED multi-purpose solar-powered LED lamp for a cost-effective rural application. This activity has being supported by CSIR through TAPSUN programme. Work for further improvement in LED device performance, development of solar cells and high electron mobility transistor (HEMT) devices on GaN-based materials and photonic crystal based structures/ devices on silicon-on-insulator (SOI) material are in progress. A DST-JSPS joint project between CEERI and the University of Tokyo, Japan has been started, to develop a monolithic white LED.
The group is ready to take up the challenges in future based on the societal/strategic requirement for the country, existing major facilities/ tools in the institute and the expertise developed. The group has already proposed activities on InGaN-based LEDs with improved efficiency, AlInGaN-based phosphor-free white LEDs, AlGaN-based UV-LEDs, in addition to two activities in healthcare mission, namely, AlGaN-based HEMT and SOI-based photonic crystal sensor-platform devices/ modules/ systems.
In future, the group would like to explore in the area of nano-photonic structures and devices based on the natural photonic structures, called as “living photonic crystal” through biomimetic studies for achieving the optimal performance of the devices and systems. The aim of the activity would be to understand the biological meaning of the optical properties of these “living photonic crystal”, as well as to exploit these properties in the design and fabrication of new bio-inspired devices/ components for an integrated systems. In addition to SOI and other flexible materials, emphasis would be given on GaN-based materials, particularly, for its high piezoelectric nature, high bandgap and mechanical strength. Therefore, this material can be used to build up a new-generation photonic integrated circuits and systems including MOEMS, where all active (source, detector, modulator, etc.), passive (waveguide, switches, filter, mirror, etc.) and opto-mechanical components can be realized in the same platform.