A quantum dot laser is a semiconductor laser that uses

quantum dot Quantum dots (QDs) are semiconductor particles a few nanometres in size, having optical and electronic properties that differ from those of larger particles as a result of quantum mechanics. They are a central topic in nanotechnology. When the q ...

s as the active laser medium in its light emitting region. Due to the tight confinement of

charge carrier In physics, a charge carrier is a particle or quasiparticle that is free to move, carrying an electric charge, especially the particles that carry electric charges in electrical conductors. Examples are electrons, ions and holes. The term is u ...

s in quantum dots, they exhibit an electronic structure similar to atoms. Lasers fabricated from such an active media exhibit device performance that is closer to gas lasers, and avoid some of the negative aspects of device performance associated with traditional semiconductor lasers based on bulk or

quantum well A quantum well is a potential well with only discrete energy values. The classic model used to demonstrate a quantum well is to confine particles, which were initially free to move in three dimensions, to two dimensions, by forcing them to occup ...

active media. Improvements in

modulation bandwidth In computing, bandwidth is the maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, data bandwidth, or digital bandwidth. This definition of ''bandwidth'' is in contrast to the field of signal p ...

lasing threshold The lasing threshold is the lowest excitation level at which a laser's output is dominated by stimulated emission rather than by spontaneous emission. Below the threshold, the laser's output power rises slowly with increasing excitation. Above thre ...

, relative intensity noise, linewidth enhancement factor and temperature insensitivity have all been observed. The quantum dot active region may also be engineered to operate at different wavelengths by varying dot size and composition. This allows quantum dot lasers to be fabricated to operate at wavelengths previously not possible using semiconductor laser technology. One challenge in the further advances with quantum dot lasers is the presence of multicarrier Auger processes which increases the nonradiative rate upon population inversion.Melnychuk, C.; Guyot-Sionnest, P.;"Multicarrier Dynamics in Quantum Dots". ''Chemical Reviews'', 121 , 4, 2021, p 2325. https://pubs.acs.org/doi/10.1021/acs.chemrev.0c00931 Auger processes are intrinsic to the material but, in contrast to bulk semiconductors, they can be engineered to some degree in quantum dots at the cost of reducing the radiative rate. Another obstacle to the specific goal of electrically-pumped quantum dot lasing is the generally weak conductivity of quantum dot films. Devices based on quantum dot active media have found commercial application in medicine ( laser scalpel,

optical coherence tomography Optical coherence tomography (OCT) is an imaging technique that uses low-coherence light to capture micrometer-resolution, two- and three-dimensional images from within optical scattering media (e.g., biological tissue). It is used for medic ...

), display technologies (projection,

laser TV Laser color television (laser TV), or laser color video display, is a type of television that utilizes two or more individually modulated optical (laser) rays of different colors to produce a combined spot that is scanned and projected across the ...

), spectroscopy and telecommunications. A 10

Gbit/s In telecommunications, data-transfer rate is the average number of bits ( bitrate), characters or symbols ( baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are mul ...

quantum dot laser that is insensitive to temperature fluctuation for use in

optical data communication Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...

s and optical networks has been developed using this technology. The laser is capable of high-speed operation at 1.3 μm wavelengths, at temperatures from 20 °C to 70 °C. It works in optical data transmission systems, optical

LAN Lan or LAN may also refer to: Science and technology * Local asymptotic normality, a fundamental property of regular models in statistics * Longitude of the ascending node, one of the orbital elements used to specify the orbit of an object in sp ...

s and metro-access systems. In comparison to the performance of conventional

strained quantum-well laser A strained quantum well laser is a type of quantum-well laser, which was invented by Professor Alf Adams at the University of Surrey in 1986. The laser is distinctive for producing a more concentrated beam than other quantum well lasers, making it c ...

s of the past, the new quantum dot laser achieves significantly higher stability of temperature. Newer, so called "Comb lasers" based on quantum dot lasers have been found to be capable of operating at wavelengths of ≥ 80 nm and be unaffected by temperatures between -20 °C and 90 °C, and allow higher accuracy with reduced fluctuations and less relative intensity noise. In development are colloidal quantum dot lasers, which would use quantum confinement to change the optical properties of the semiconductor crystals (≤ 10 nm in diameter) through solution-based rearrangements of quantum dots.

References

{{Display Technology Semiconductor lasers Quantum dots

See also

References