About the Project
Start date: October 2017
Duration: 3.5 years
Important information: This project is part of a collaboration with the group of Prof Maria Tamargo, Department of Chemistry, City College of New York and the Nanoscience Initiative, City University New York (CUNY). The successful applicant will be expected to spend some time in the laboratory of Prof Tamargo in New York.
Background: The development of semiconductor laser technology to target the blue-green-yellow spectral region has focused primarily on two material systems: III-V semiconductors, and II-VI semiconductors. Both technologies have failed to deliver performance in the “green gap,” and II-VI technology in particular has suffered lifetime problems caused by defects associated with electrical injection. However, there is now the opportunity to use the high powers recently delivered at short wavelengths from GaN laser diodes to circumvent these lifetime issues by optically-pumping the II-VI material in the semiconductor disk laser (SDL) format pioneered at the Institute of Photonics (see e.g. [1]). Diode-pumped SDLs not only offer multi-Watt performance, but are also commercially viable alternatives to solid-state lasers. The external laser cavity produces the high-quality output beam typical of conventional solid-state lasers, and the semiconductor gain region allows wavelength flexibility. Currently these lasers are restricted to fundamental operation in the red/infrared region using III-V semiconductor materials.
The Tamargo group are world leaders in II-VI semiconductor epitaxy having developed a unique two-chamber MBE system that allows them to grow very high quality II-VI multi-quantum well structures on III-V buffer layers lattice-matched to InP. This capability allows the Hastie group to employ bandgap and strain engineering to target gain structures with emission throughout the visible region. Over the past few years, Strathclyde and CUNY working together have made significant advances towards realising semiconductor disk lasers using this material. We have designed multi-QW gain structures and mirrors which have been grown by CUNY before processing and characterisation at the IoP, including the transfer of thin films to diamond and micro-LED arrays [2].
Project objective: This project will build on our pump priming work to demonstrate the first direct visible emission from an SDL based on state-of-the-art II-VI semiconductor epitaxy. The research may include but is not limited to: modelling and design of ZnMgCdSe SDL gain structures; growth of SDL gain structures at CUNY; structure characterization before and after processing, e.g. TEM and X-ray diffraction at CUNY and temperature dependent photoluminescence and laser characterisation at the IoP; development of processing techniques; design, fabrication and demonstration of II-VI SDL systems. We will target novel results that will be published in the best journals in the field.
Research environment: This studentship will benefit from and contribute to a wider project supported by the EPSRC UK Quantum Technology Hub for Sensors and Metrology (www.quantumsensors.org), which involves multiple academic and industry partners. Dr Hastie leads the ‘Special Lasers’ workpackage of the Hub, developing narrow linewidth lasers at novel wavelengths for the optical clock systems of the other partners. We have an existing collaboration with the group of Hub Director Prof Kai Bongs at the University of Birmingham, using these lasers for cooling strontium. Dr Hastie is also the academic partner in an Innovate UK project in collaboration with the Fraunhofer Centre for Applied Photonics and M Squared Lasers Ltd to support the translation of the group’s laser technology to industry.
Institute of Photonics: The Institute of Photonics (IoP), established in 1996, is a commercially-oriented research unit, part of the Department of Physics, University of Strathclyde (www.photonics.ac.uk). The Institute’s key objective is to bridge the gap between academic research and industrial applications and development in the area of photonics. The offices, laboratories, and cleanrooms of the IoP are located in Strathclyde’s new Technology & Innovation Centre in Glasgow City Centre.
[1] Calvez et al, Laser & Photonics Reviews 3, p407 (2009).
[2] Jones et al, Journal of Thin Solid Films 590, p84 (2015).
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