Collaborative Research: First-Principle Control of Novel Resonances in Non-Hermitian Photonic Media

Nontechnical description:

This NSF award supports an integrated research, education, and outreach project that focuses on studying a novel behavior of light within solid materials. Optical science has long pursued the ability to manipulate various properties of light and other invisible waves, such as infrared light and microwaves. Traditional examples include bending light with mirrors and lenses and generating light with lasers and LEDs.

This project adopts a unique approach by delving into the exploration of how the active property of optical materials, specifically their suitability for attenuation or amplification of light, can profoundly transform their interactions with the environment. This aspect, which has received limited investigation in the past, presents a compelling avenue for understanding and harnessing the dynamic behavior of light in novel ways.

The outcomes of this investigation are expected to deliver a new type of light-matter interaction, thereby advancing our fundamental understanding of optics, physics, materials science, and optoelectronics. Moreover, by introducing a novel paradigm for how light perceives its environment, the project aims to significantly enhance the functionality of photonic devices used in optical communications and computing.

This includes the development of an ultra-broadband tunable laser capable of achieving a wavelength tuning range surpassing the current state-of-the-art, by more than one order of magnitude. These advancements have far-reaching implications across industries and in our daily lives. Leveraging the resources of the City University of New York, the largest urban university system in the US, and the University of Pennsylvania, a national leader in education innovation, the researchers will collaborate with multiple outreach units to increase awareness and interest in modern optics and photonics among K-12 students in New York City and the greater Philadelphia area.

This interdisciplinary project also provides valuable research opportunities for graduate, undergraduate, and advanced high-school students, with a focus on recruiting and mentoring students from underrepresented groups in STEM. Technical description:

Traditionally, the interaction between light and matter occurs when an oscillating electromagnetic field resonantly engages with charged particles, such as dipoles in dielectrics. This interaction can be modeled using coupled oscillators, where the passive photonic modes represent the electromagnetic environment defined by the real part of the matter's refractive index.

Two types of light-matter interactions are typically defined based on the coupling strength between matter and photonic modes. However, these definitions overlook an important aspect of matter: the imaginary part of the matter’s refractive index, i.e., optical gain and loss, which can significantly impact their interactions. In this collaborative project, the principal investigators aim to establish a complex non-Hermitian photonic environment through first-principle control of the imaginary part of the refractive index.

The results showcase a novel type of light-matter interaction that is exclusively governed by the system's non-Hermiticity, arising from previously unexplored photonic active resonances. The project combines integrated theoretical and experimental research to design photonic active resonators through strategic waveguide mode engineering on the III-V semiconductor platform to unravel their unique properties and further leverage them for the development of robust intrinsic single-mode lasing with an ultra-broadband tunability.

These advancements will lay the groundwork for a new generation of integrated photonic devices for optical communication and computing.

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.