High-power, single-mode interdigitated slow photon laser diodes

Project Description: Lasers for directed energy (DE) capabilities provide high-precision directionality and a significant reduction in the recurring cost of kinetic weapons. However, existing DE systems require high energy sources and complex storage, management, and conversion processes. Fabry–Pérot laser diodes (FP–LDs) are the most widespread and simple class of LDs, in which two mirrors are created at each side of a PN diode to form a cavity laser resonator. Upon electrical pumping, recombination of electrons and holes in the junction region of the PN LD results in the spontaneous emission of photons, which subsequently travel along the waveguide through multiple reflection at both ends of the cavity, and undergo amplification by stimulated emission. When there is more amplification than loss, then the LD begins to lase. Despite their simplicity and ease of operation, the power output and beam quality of FP–LDs are constrained by: i) losses associated with absorption and incomplete reflection from the end mirrors, which limit the maximum output power to ~12 W; ii) multiple optical frequency outputs (spacing of ~100 GHz), which result in poor beam quality; and iii) mode ‘hops’ or dual-mode oscillations upon temperature changes. FP–LDs can produce high-power beams (up to 1 kW) through ‘arrays’ or ‘multi-single emitters’, but typically at the expense of high electrical pumping power (~90 A). It is also possible to substantially reduce optical frequency modes and linewidth by coupling FP–LDs to external optical resonators, but at the cost of increasing architectural complexity and operability. So new FP–LD architectures capable of ‘filtering’ undesired modes and maximise stimulated emission power at desired wavelengths by increasing the dimensions of the active area and harnessing highly selective optical phenomena are urgently needed to realise high-power, narrow linewidth DE lasers at low electrical pumping.

This project will engineer the first high-power, single-mode FP–LDs by integrating an interdigitated PN junction with a 2D nanoporous photonic crystal structure to increase the active area and radiative rate at a selective wavelength through the ‘slow photon’ effect. At a more fundamental level, the project will seek to understand and design light–matter interactions in this new class of LD to achieve precise, tailorable modulation of high-power lasing across the electromagnetic spectrum, from UV to NIR.

Student Requirements: The candidate will preferably have a Master degree in a related field and publications (recommended). The successful candidate will join a team of expert researchers seconded from The University of Adelaide for a PhD position. His/Her skillset will complement the University's considerable existing expertise in renewable energy generation and materials engineering.

Supervisor: The project

will be supervised by A/Prof. Abel Santos (https://www.adelaide.edu.au/directory/abel.santos#). He has demonstrated national and international research standings in nanofabrication and applied photonics, and unique expertise in fabricating nanostructures with precisely engineered features at the nanoscale for specific applications through anodisation. He has an excellent track-record of publications (>117 research articles) in top international journals, and a strong history of successful competitive grants (>$9.6M) including one ARC DECRA, two ARC DPs, four ARC LIEFs, one APRIL Innovation and Commercialisation Project, and one Australia–India Research Strategic Grant. He has mentored and supervised three ECRs and 15 PhDs (seven completions and eight current). Internationally, he has been recognised as one of world’s 2% researchers by Stanford University (since 2019), emerging investigator by the editorials of Journal of Materials Chemistry C (2017) and ACS Applied Materials and Interfaces (2021), and holds an adjunct visiting professorship at his alma mater university (URV, Spain) in recognition of his significant contributions over the past ten years. He has strong experience in industrial engagement and translation of findings, project management, and international collaboration. He will lead this aspect of the project and oversee the experimental design, manuscript preparation, dissemination of results, and supervision.

Facilities: During the last twelve years our team has built research infrastructure, including four ARC LIEF grants, and established a substantial suite of fabrication and characterisation facilities; these are cutting-edge environments in nanofabrication and optical and electrochemical chemo- and biosensing, including two fully computerised semi-industrial anodisation stations, two electrochemical workstations, two metal and oxide coating systems, 3D printing microfluidic chips, optical microscope coupled with optical fibre spectrometer, digital imaging characterisation, and several UV–visible–NIR spectrometers. Beyond our own independent research laboratory, we have access to a broad range of world-class nanofabrication and characterisation facilities. UoA’s CHEM ENG provides an outstanding research environment with an analytical laboratory worth >$15M, which houses over 40 items of equipment, including research infrastructures of relevance to the proposed research (ALD, Raman, FTIR, PL, XRD, TGA–MS/FTIR, HPLCs, Mastersizer, DLS, BET). UoA also hosts the centre for Advanced Microscopy and Microanalysis (Adelaide Microscopy), which enables access to state-of-the-art SEMs, EDAX, TEMs, and HRTEM. Further to that, as members of the Institute for Photonics and Advanced Sensing (IPAS) our research group has access to multiple research infrastructures across different Schools, Departments, and Research Institutes, such as the School of Electronic Engineering (THz spectroscopy characterisation facility), the Department of Chemistry (NMR 600 MHz with cryoprobe and 500 MHz with autosampler spectrometers), and IPAS (Optofab Node of ANFF with IR and visible ellipsometers, optical profilers). Our team has also access to the research infrastructures located at the central facilities of the South Australian and Victorian nodes of the Australian National Fabrication Facility (ANFF–SA and –VIC), which are world-class nanofabrication centres with >$100M investment in micro- and nanotechnology infrastructure, including cleanrooms classes 10,000 and 100, photolithography and nanolithography, and deposition systems at subsidised costs.

Scholarship: The University of Adelaide offers competitive Research Scholarships of $AU 32,500 p.a. Candidates will have to apply to gain a scholarship