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Researchers in Cambridge, England (Cambridge University) in a recent journal of Applied Physics Letters (Applied Physics Letters) in the journal published about "electric and electrical tunable quantum light" (Electrically driven and Electrically tuneable quantum light sources) results, display on a single chip closely adjacent two quantum dot light emitting diodes (leds), to be able to play a tunable, all electrical quantum light effect.
In the experiment, the researchers used driven by electric stimulating emitted by the LED light source, excitation of adjacent diodes, quantum dot (QD). They can through the quantum confinement Stark effect (Stark effect), tuning from adjacent drivers diode emission wavelength of QDS.
Researchers thought is through easy to integration to the semiconductor device with photon cavity of wafer surface structure, in accordance with the requirements of the quantum computing application become entangled photon pairs.
In this paper, the researchers showed the generate electricity from the electrical tunable light source trigger resistance together method of beam of light.
To this end, the researchers on the single chip design for 16 kinds of tuning the diode structure separately. The device is composed of 180 x 210 microns plane microcavity LED, which contains a layer of indium arsenide (InAs) quantum dot layer, embedded in a Al0.75 Ga0.25 As barrier layer of 10 nm arsenide ingot (GaAs) in the quantum well.
In InAs quantum dots and quantum well above and below the growth of many distributed Bragg reflector (DBR), is used to form the half wave cavity, in order to increase the vertical launch QD light source parts, at the same time as the light from the InAs wetting layer emission levels of waveguide. DBR and from the top to the bottom DBR doped p-type and n-type respectively, form the diode structure is suitable for electric excitation.
The main idea is that the researchers' use of LED light, stimulate the adjacent diode quantum dots ". LED to run forward biased, the broadband light emitting from the InAs wetting layer by the wetting layer above and below the Bragg reflector horizontal guide.
And as part of the emitted light arrived at nearby LED, part of the light is absorbed by the wetting layer, produced by adjacent diode quantum dots in the capture of exciton, which may lead to a quantum of light emission.
The element has a p-type doped region (red), nature area (transparent) and n type doping area (blue). Driven by forward bias (left) strongly LED emission light source (shown as blue beams of light), adjacent components in quantum dots (right). Quantum dots to launch anti bunching light (green).
Due to adjacent plane microcavity anticross between matching the emission wavelength of QDS was, so to improve the upward into the collection of optical element QD emission proportion. Through changing the second diode bias, can through the effects of Stark shift conversion wavelength tuning, and the intensity of adjacent diode emission of light can be through the change the first diode voltage control.
The researchers also confirmed to tune the second diode exciton in the fine structure division, as a function of the whole field, allowing it to use such components as entangled photons of light source.
From the first diode (1) the wetting layer emission of light is absorbed wetting layer adjacent diodes, charge carriers in the diodes and through a quantum dot after ripping, a quantum light source. Wetting layer launch (left) and quantum dots (right) is the actual data, and display the wetting layer absorption is a copy of the emission data, and is only used to display the operating principle of element
In the future, the researchers hope to be able to improve the efficiency of the element, as between the different diodes give more emission directionality, may adopt one-way waveguide antenna or LED, so as to improve the efficiency of the cross coupling. In principle, a driver of LED can inspire many tunable LED.
And combined with rapid electronic components and low after the RC constant element, can through the change of diodes (1) offset by adjusting the "pump", or through changing diodes (2) the bias to adjust the wavelength, and in accordance with the requirements of entangled photons.