How semiconductor lasers can create multiple wavelengths from one platform

A new research project at Vrije Universiteit Brussel (VUB / Free University Brussls, Belgium) is to investigate how networks of interacting semiconductor lasers can generate and manipulate multiple wavelengths of light together on a single photonic platform. VUB’s Brussels Photonics (B-PHOT) division says project COMBYNE “could yield compact and energy-efficient photonic engines for future optical and terahertz communication systems.”

Prof. Dr. Pablo Marin-Palomo, a researcher at VUB and B-PHOT, has been awarded a European Research Council Starting Grant for COMBYNE (terms of the funding were not disclosed). Over the next five years, he plans to leverage the interaction between multiple lasers on a single chip to generate a flexible frequency comb on a monolithic platform. The aim is to establish a new class of compact photonic engines for future optical and terahertz communication systems.

At the heart of the COMBYNE project is the optical frequency comb. VUB explains, “While lasers typically produce only one output wavelength, an optical frequency comb source generates dozens or even hundreds of evenly-spaced wavelengths. Frequency combs have applications in metrology, spectroscopy and optical and terahertz communications.

“In a communication system, each wavelength can carry a separate stream of data, allowing one compact light source to support many parallel channels. This could help communication systems accommodate rapidly growing data traffic while limiting their energy consumption.”

While such applications would benefit from compact, reconfigurable frequency comb sources that can be manufactured at scale, current sources are still mostly based on multi-platform integration, since monolithic frequency comb sources can face limitations in bandwidth and coherence. In addition, frequency combs face a long-standing trade-off between bandwidth and flexibility: broadband frequency combs are challenging to tune, while reconfigurable frequency combs are limited in bandwidth.

Programmable source

With COMBYNE, Marin-Palomo intends to develop a programmable optical frequency comb source on a monolithic platform by harnessing the nonlinear dynamics of mutually coupled semiconductor lasers. “The core idea is to turn the interaction between lasers into an advantage,” Marin-Palomo said. “We want to understand those interactions deeply enough to engineer them.”

The project will study networks of coupled semiconductor lasers and investigate how their collective dynamics can be used to engineer a reconfigurable optical frequency comb. It will connect fundamental laser physics, photonic-chip design and high-speed communication experiments. Marin-Palomo’s team will first identify and understand useful dynamical regimes, then translate those findings into integrated photonic devices. The most promising concepts will subsequently be tested using high-speed data signals.

The ERC Starting Grant will enable Marin-Palomo to establish a dedicated COMBYNE team at VUB B-PHOT and to develop the models, integrated photonic devices and experiments required for the project. “Receiving this award gives us the opportunity to build a dedicated team, develop the idea fully and explore the new research directions that emerge along the way,” said Marin‑Palomo.