A quantum dot laser is a

semiconductor laser The laser diode chip removed and placed on the eye of a needle for scale A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with e ...

that uses

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

s as the

active laser medium The active laser medium (also called gain medium or lasing medium) is the source of optical gain within a laser. The gain results from the stimulated emission of photons through electronic or molecular transitions to a lower energy state from a h ...

in its light emitting region. Due to the tight confinement of charge carriers 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 laser A gas laser is a laser in which an electric current is discharged through a gas to produce coherent light. The gas laser was the first continuous-light laser and the first laser to operate on the principle of converting electrical energy to a lase ...

s, 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 occupy ...

active media. Improvements in modulation bandwidth,

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 t ...

relative intensity noise Relative intensity noise (RIN), describes the instability in the power (physics), power level of a laser. The noise term is important to describe lasers used in fiber-optic communication and LIDAR remote sensing. Relative intensity noise can be gen ...

, 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 A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fir ...

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 medical ...

), 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 mu ...

quantum dot laser that is insensitive to temperature fluctuation for use in optical data communications 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 LANs and metro-access systems. In comparison to the performance of conventional strained quantum-well lasers 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

. 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