The Comb That Can Detect Exoplanets And Diseases

Minimal optical dipsticks - microcams - can be used to detect exoplanets, keep track of our health and make the internet more energy efficient. Now researchers from Chalmers are presenting an innovative micro-comb that can contribute to advanced technology solutions becoming a reality.

The micronucleus can be described as an optical tuning fork, or a light ruler. It is created using a laser and an optical microresonator. The light circulates in a small resonant box and forms a comb that emits a myriad of colors - or frequencies. These are separated with great accuracy, as are the markings on a ruler.

In a recently published article in prestigious Nature Photonics, eight Chalmers researchers describe a new type of micro comb on a chip, where they use two microresonators instead of one. The innovation makes it possible to increase energy efficiency ten times, compared with today's leading technology. The comb is also both adjustable and possible to mass produce.

And - What makes our new results important is that they offer a unique combination of different long-awaited properties in terms of efficiency, energy efficiency and precision, says Óskar Bjarki Helgason, doctoral student at the Department of Microtechnology and Nanoscience at Chalmers and the scientific article's lead author.

Wide areas of use
Since almost all optical measurements can be connected to light frequencies in some way, the micro comb can be useful in many different contexts in the future. For example, it could be used to reduce energy use in data centers for fiber optic communication systems and thus make the Internet more energy efficient. The cam can also be useful in self-driving vehicles by being able to measure distances with high precision. It could also calibrate measuring instruments in space observatories used to try to detect planets outside our solar system, so-called exoplanets.

Extremely accurate atomic clocks and mobile apps that can keep track of our health are other exciting areas where the micro comb opens up new possibilities. For example, it could analyze our exhaled air to detect diseases at an early stage.

Can provide answers to questions that have not been asked yet
The new chip-based micro-comb is so small that it fits on the end of a hair, but Chalmers researchers are not the first to present micro-combs on a chip. The new thing is that they use two microresonators, which means that they can overcome several known limitations in the research field.

- In order for technology to be able to take the step from the lab to society, the micro-comb needs to be integrated with other technology solutions. This is a major engineering challenge that is probably five to ten years ahead. It requires large investments, but I am sure we will get there. The most exciting uses can also be the ones we have not even thought of yet! For example, what can we do with ten micro-combs that we cannot do with one? says Victor Torres Company, which leads the research project at Chalmers.

The scientific article is written by Óskar B. Helgason, Francisco R. Arteaga-Sierra, Zhichao Ye, Krishna Twayana, Peter A. Andrekson, Magnus Karlsson, Jochen Schröder and Victor Torres Company at the Department of Microtechnology and Nanoscience at Chalmers.

The research has been carried out at Chalmers and has been funded through research grants from the European Research Council and the Swedish Research Council

More about: Frequency combs and micro combs

• A frequency comb is a special light source where the transmitted frequencies / colors are evenly distributed. It acts much like a ruler of light, where the markers set the frequency scale over a part of the electromagnetic spectrum, from ultraviolet to infrared. The location of the markers, or the teeth of the comb, can be linked to a known reference and therefore acts as a measuring stick.
• The first frequency comb saw the light of day in the late 90's and the revolutionary measurement method was awarded the Nobel Prize in Physics in 2005.
• A micro comb is a more modern technology that does not require position-locked lasers. With only one laser source, it can generate light pulses at very high speeds.
• Micro combs have several advantages that make them interesting for different technical applications. They are extremely small, energy efficient, adaptable and possible to mass produce. They are also distinguished by having a very large frequency distance between the markers / teeth, usually between 10 and 1000 GHz (gigahertz), which opens up possibilities for new areas of use.