Project Summary: Large-scale approaches for nanolaser optimization

The emission of light at the nanoscale is of great importance for information processing, medicine and fabrication for optical circuits. Optical circuits would improve processing speeds and decrease the energy consumption necessary to operate data centres. This is due to the manipulation of light which can carry more information at faster speeds more efficiently than electrical signals over copper.

An important element of optical circuits is the light source; in our case, we focus on semiconductor nanowires. These tiny crystals can emit signals in the form of light and due to their compact size (one tenth the thickness of a human hair) and electronic properties; they can be easily integrated with current silicon technology. However, nanowires cannot be fabricated individually; they require a process which “grows” very big quantities. So, when we want to integrate them with current technology, it is necessary to select the ones with the best light emission quality.

We have developed a technique that allows us to test thousands (from 1000 to 10,000) of these wires rapidly and gather a large amount of information from each one. This gives us the advantage of finding the top performing wires which can be isolated and retrieved for their implementation in optical circuits. Additionally, we can perform a large statistical study to find trends in nanowires performance as a function of particular characteristics. For example, one could find that longer wires tend to emit light more efficiently, or a change in its chemical composition makes them better candidates for lasers.

These findings are a good stepping stone towards the improvement of nanowire design and fabrication.

References:

New Paper – Optical Study of p-Doping in GaAs Nanowires for Low-Threshold and High-Yield Lasing

Our new work on large-scale statistical spectroscopy to optimize nanowire lasers is published today in Nano Letters. In this work, PhD student Arturo studied thousands of nanowires to identify the lowest threshold nanowire, as well as to model emission to identify the primary sources of non-radiative emission.

By quickly sorting nanowires by doping and length, he was able to demostrate sub-sets with over 90% yield and class-leading thresholds, pointing the way towards electrically injected nanolasers.

Congratulations Arturo!

nl-2018-04048u_0006
(Left) Far-field emission from a record breaking nanowire laser, emitting at room temperature and low exciation levels. (Right) Doping vs Quantum efficiency, showing two key limiting behaviours.

Reference: “Optical Study of p-Doping in GaAs Nanowires for Low-Threshold and High-Yield Lasing”, Juan Alanis et al., Nano Letters, ASAP 2018, DOI: 10.1021/acs.nanolett.8b04048