Researchers the world round are working to develop optical chips, where light can be controlled with nanostructures.
These could be used for future circuits based on light (photons) instead of electron - that is photonics instead of electronics. But it has proved to be impossible to achieve perfect photonic nanostructures: they are inevitably a little bit imperfect.
The nanolaser is based on the disorder in the pattern of holes in the photonic crystal. The light source is built into the photonic crystal itself, which is clear as glass and when the light hits a hole it is reflected and is channeled into the so-called waveguide, the crystal's middle lane. But the light is thrown back and forth in the photonic crystal and due to imperfections is intensified and spontaneously turns into laser light.
Credit: Quantum Photonics, Niels Bohr Institute
Now researchers at the Niels Bohr Institute in collaboration with DTU have discovered that imperfect nanostructures can offer entirely new functionalities. They have shown that imperfect optical chips can be used to produce 'nanolasers', which is an ultimately compact and energy-efficient light source. The results are published in the scientific journal Nature Nanotechnology.
The researchers are working with extremely small photonic crystal membranes - the width of the membrane is 25 micrometer (1 micrometer is one thousandth of a millimeter), and the thickness is 340 nanometers (1 nanometer is one thousandth of a micrometer). The crystals are made of the semiconducting material gallium arsenide (GaAs).
A pattern of holes are etched into the material at a regular distance of 380 nanometers. The holes have the function of acting as built-in mirrors that reflect the light and can thus be used to control the spread of the light in the optical chip. The researchers have therefore tried to achieve as perfect a regular structure of holes as possible to control the light in certain optical circuit.
Unavoidable disorder exploited
But in practice it is impossible to avoid small irregularities during the manufacture of the optical chips and this can be a big problem, as it can result in the loss of light and therefore reduced functionality. Researchers at the Niels Bohr Institute have now turned the problem of imperfections into an advantage.
"It turns out that the imperfect optical chips are extremely well suited for capturing light. When the light is sent into the imperfect chip, it will hit the many small irregular holes, which reflect the light in random directions. Due to the frequent reflections, the light is spontaneously captured in the nanostructure and cannot escape. This allows the light to be amplified, resulting in surprisingly good conditions for creating highly efficient and compact lasers," explains Peter Lodahl, professor and head of the Quantum Photonic research group at the Niels Bohr Institute at the University of Copenhagen.
Experiment with built-in light
The researchers in Quantum Photonics at the Niels Bohr Institute, led by Professor Peter Lodahl and Associate Professor Søren Stobbe, designed the photonic crystal and carried out the experimental studies in the research group's laboratories.
The light source is integrated into the photonic crystal itself and is comprised of a layer of artificial atoms that emit light (the basic component of light is photons). The photons are sent through the crystal, which is clear as glass and has a pattern of tiny holes. When a photon hits a hole it is reflected and channeled into the so-called waveguide, which is a 'photon track' that can be used to guide the photons through the photonic crystal. However, due to the imperfect holes the light will be thrown back and forth in the waveguide of the photonic crystal, intensifying it and turning it into laser light.
The result is laser light on a nanometer scale and the researchers see great potential in this.
The dream of a quantum Internet
"The fact that we can control the light and produce laser light on a nanometer scale can be used to create circuits based on photons instead of electrons, thus paving the way for optical quantum communication technology in the future. With built-in laser sources, we will be able to integrate optical components and it allows for the building of complex functionalities. Our ultimate dream is to build a 'quantum internet', where the informations is coded in individual photons," explain Peter Lodahl and Søren Stobbe, who are excited about the results, which show that the unavoidable disorder in optical chip is not a limitation and can even be exploited under the right conditions.
For further information contact:
Gertie Skaarup | idw - Informationsdienst Wissenschaft
Suzaku, Herschel link a black-hole 'wind' to a galactic gush of star-forming gas
26.03.2015 | NASA/Goddard Space Flight Center
Tiny Bio-Robot Is a Germ Suited-Up with Graphene Quantum Dots
25.03.2015 | University of Illinois at Chicago
In an experiment at the Department of Energy's SLAC National Accelerator Laboratory, scientists precisely measured the temperature and structure of aluminum as...
The IPH presents a solution at HANNOVER MESSE 2015 to make ship traffic more reliable while decreasing the maintenance costs at the same time. In cooperation with project partners, the research institute from Hannover, Germany, has developed a sensor system which continuously monitors the condition of the marine gearbox, thus preventing breakdowns. Special feature: the monitoring system works wirelessly and energy-autonomously. The required electrical power is generated where it is needed – directly at the sensor.
As well as cars need to be certified regularly (in Germany by the TÜV – Technical Inspection Association), ships need to be inspected – if the powertrain stops...
When an earthquake hits, the faster first responders can get to an impacted area, the more likely infrastructure--and lives--can be saved.
The Atlantic overturning is one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards. Also known as the Gulf Stream system, it is responsible for the mild climate in northwestern Europe.
Scientists now found evidence for a slowdown of the overturning – multiple lines of observation suggest that in recent decades, the current system has been...
Because they are regularly subjected to heavy vehicle traffic, emissions, moisture and salt, above- and underground parking garages, as well as bridges, frequently experience large areas of corrosion. Most inspection systems to date have only been capable of inspecting smaller surface areas.
From April 13 to April 17 at the Hannover Messe (hall 2, exhibit booth C16), engineers from the Fraunhofer Institute for Nondestructive Testing IZFP will be...
25.03.2015 | Event News
19.03.2015 | Event News
17.03.2015 | Event News
26.03.2015 | Trade Fair News
26.03.2015 | Trade Fair News
26.03.2015 | Life Sciences