Collaborative Research: Engineering fractional photon transport for random laser devices

The rapid development of miniaturized lasers enabled consumer applications of optical technology that have radically transformed our information society ranging from high-speed communication systems to integrated optical sensors, scanners, and high-resolution imaging devices. Moreover, the emerging paradigm of quantum information technology requires our ability to enhance the rate of optical emission processes in miniaturized laser devices that can operate efficiently over multiple frequency bands and release “photons on demand”.

Responding to these challenges, this research project advances the understanding of novel laser devices that rely on engineered wave transport and localization effects in structurally disordered media. The research team utilizes novel computational methods in partnership with nanofabrication and device characterization to design and develop a new class of laser structures with broadband behavior for use as miniaturized light sources in the next generation of power-efficient nanophotonics devices, such as on-chip miniaturized spectrometers, optical sensors, imaging systems, and more robust quantum sources.

The project supports one graduate student at Boston University and at the University of Utah and encourages the involvement of undergraduate students in the research through a vibrant outreach program at both institutions. The computational and experimental frameworks developed by the PIs will be disseminated through course projects at both Boston University and the University of Utah.

An important component of this outreach plan is to attract a broad range of students to a career in computational science and optical engineering through participation in the project.

This project responds to the compelling challenges posed by the multi-scale modeling of random laser devices with tailored photon transport properties by proposing a combined theoretical and experimental approach based on the efficient numerical solution of fractional differential operators in non-regular three-dimensional domains. Fractional calculus operators exhibit non-local characteristics in space and history-effects in time that naturally describe correlation effects in the wave transport across non-homogenous, aperiodic media.

These effects typically provide significant discretization and computational challenges. However, building on the initial success of fractional wave-diffusion equation models for anomalous wave transport, this project develops a new methodology to efficiently couple fractional transport equations to the electrodynamics description of active photonic devices with complex non-periodic geometries.

To accomplish this task, we build on the success of the open-source spectral/hp element library Nektar++ framework designed to support the development of high-performance scalable solvers for partial differential equations using the spectral/hp element method. The project uses novel mathematical techniques of fractional operators in concert with the fabrication and experimental characterization of random laser devices realized from sub-wavelength photonic membranes.

Based on this efficient platform, the project demonstrates lasing behavior in tailored random structures and aperiodic media that exhibit ultra-slow photon sub-diffusion phenomena by design. The primary intellectual merit of the project is the development of a novel class of cost-effective, miniaturized, disorder-engineered random lasers with tailored photon diffusion properties that can find applications as more robust photon sources for classical and quantum optical information processing.

This project enables a substantial broader impact by providing the foundation for the next generation of random laser devices for optical imaging, sensing, and spectroscopy, and laying the foundation for broader adoption of fractional operators in computational photonic models.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.