Laser breakthrough to boost applications in cutting-edge tech

A breakthrough in laser technology from the University of Glasgow could pave the way for more compact, cost-effective, and easily manufactured optical and quantum devices. Researchers have developed a narrow-linewidth laser on a single microchip, achieving the highest performance ever recorded for its class of semiconductor lasers.

The new system, dubbed the ‘topological interface state extended laser with optical injection locking’ (MOIL-TISE), marks a significant advance in monolithic distributed feedback (DFB) laser technology. It produces laser light with a linewidth of just 983Hz — far narrower and purer than the MHz-range linewidths typical of current monolithic DFB lasers. This level of spectral purity is crucial for applications requiring highly stable beams with minimal frequency fluctuation.

Historically, achieving such performance required hybrid integration and bulky external components, which limited the practicality of these systems for on-chip applications. The MOIL-TISE laser overcomes these limitations by integrating all components on a single indium phosphide chip, fabricated at the University’s James Watt Nanofabrication Centre.

Dr Xiao Sun, first and corresponding author of the study, said: “The University of Glasgow is unique in the UK in that it is possible to take a project like this from an initial idea to a fully-featured prototype without leaving our campus. The James Watt Nanofabrication Centre enabled us to design, fabricate and test our MOIL-TISE system, dramatically accelerating the research process.”

Micro-ring resonator
The chip’s design divides it into three regions, each with a distinct optical phase, ensuring even light distribution. A micro-ring resonator integrated into the chip allows internal light recycling, which stabilises the laser’s performance and contributes to its exceptionally narrow linewidth.

Professor Lianping Hou, co-corresponding author from the James Watt School of Engineering, highlighted the system’s versatility, said: “Our MOIL-TISE laser makes three significant breakthroughs and improvements in this field. It is the first monolithic device of its kind, with every component integrated on a single chip. It can create a laser with remarkable frequency purity, the highest-ever achieved in a monolithic distributed feedback laser of this kind. It is also capable of easily switching between optical phases, a property required in the quantum key distribution systems which will underpin the unbreakable encryption and communication devices of the future.”

The research was supported by the University’s Critical Technologies Accelerator (CTA), funded through the Glasgow City Region’s Innovation Accelerator programme. The team’s findings are detailed in the paper ‘Narrow-linewidth monolithic topological interface state extended laser with optical injection locking’, published in Science Advances.