Researchers from the University of Twente's MESA+ research institute and the photonics company LioniX International have developed the world's most narrowband diode laser on a chip. This laser represents a breakthrough for the fast-growing field of photonics, bringing applications like 5G mobile Internet and far more accurate GPS measurements closer. Research leader Professor Klaus Boller presented the research results during a scientific conference at Laser World in Munich.
"We are slowly reaching the boundaries of what's possible with electronics." says Boller. "That is why scientists and the private sector are committed to photonics. This involves the deployment of photons (light particles) for transporting and processing data."
"For photonic chips to function as efficiently as possible, it's important to be able to properly control the light signals. This means that all the light particles being transmitted should have the same frequency and therefore the same colour. The University of Twente researchers have developed a minuscule laser on a chip with a maximum linewidth (the maximum uncertainty in frequency) of just 290 Hertz. That means this is the most accurate laser on a chip that has ever been created - and by a factor of ten".
The newly-developed laser is tunable, which means that users can choose the colour of the laser themselves, within a broad spectrum range.
More accurate monitoring of vital infrastructure
René Heideman of LioniX International has been closely involved in the project. "These next generation lasers will allow for much better accuracy in metrology systems, and for next generation navigation! Secondly, we hope it will allow for the next generation Ultra Dense WDM. The new laser will bring several important applications within reach, such as controlling smart movable antennae on 5G base-stations bringing about major savings in energy consumption. We can also expect more accurate GPS systems and smart sensors for monitoring the structural integrity of buildings and bridges."
"LioniX International has developed the narrow linewidth tunable laser based on a hybridly integrated external cavity laser. The concept uses state-of-the-art Photonic Integrated Circuit technology and has distinctive advantages including, high-power capability, ultra narrow line width, as well as broadband tuning. It is all packed into a small size."
"It is going to be possible to manufacture smaller yet very high power lasers inside the TriPleX platform. This is not possible with InP alone. Yet, this is turning out to be essential for a lot of applications such as Optical Beam Forming Networks, RF analog links for the new 5G networks. We will create hybrid lasers in other wavelength regimes as well, by using other gain material, and we intend to use the same type of combination to create swept source light sources."
LioniX International is already selling a commercial version of this laser on a chip, which has already been sold to a variety of customers already.
The hybrid laser as created for Klaus Boller's group is the next step, and not yet commercially available, although it could be manufactured in series as the market demands: its linewidth is better than 1 kHz, typically just 290 Hz.
External cavity tunable laser
The main concept is shown in the figure below: A gain section PIC is hybridly attached to a tunable reflector PIC creating an external cavity laser. The gain section creates the first mirror and the necessary gain, the silicon nitride (Si3N4) based TriPleX™ PIC acts as a tunable wavelength dependent mirror.
Additional application specific functions can be integrated on the same TriPleX™ PIC to create custom features.
Towards other applications
Another advantage of this approach is that the technology can be used in other than C-band applications. Gain section PICs are available in ranges in the VIS, NIR and MIR as well. TriPleX™ operates over a broad bandwidth of 405 to 2350 nm.
Photonics in Twente
The research was carried out by Youwen Fan and Klaus Boller of the Laser Physics and Nonlinear Optics department at the University of Twente MESA+ research institute, Applied Nanophotonics, in collaboration with Ruud Oldenbeuving, Chris Roeloffzen, Marcel Hoekman, Dimitri Geskus, and René Heideman of the company LioniX International.