Final answer:
Quantum dot semiconductor lasers differ from conventional semiconductor lasers in that they use nano-sized quantum dots that allow for finer emission control and improved brightness and stability. These lasers can excite all colors with the same wavelength and have a longer lifetime, offering benefits in biological research and other high-stability applications.
Step-by-step explanation:
The main differences between a semiconductor laser and a quantum dot semiconductor laser, in addition to size, involve their operating principles and the materials used. A semiconductor laser, commonly a diode laser, operates by passing a current through a silicon-based material, which excites electrons to produce laser light. This type of laser typically has a continuous output in the milliwatt range. On the other hand, a quantum dot semiconductor laser utilizes nano-sized crystals, known as quantum dots, which are embedded in another semiconductor nanocrystal. These dots act as potential wells for electrons, offering improved brightness and stability compared to conventional materials.
Quantum dots allow for the excitation of all colors with the same incident wavelength, and they feature a longer lifetime than conventional phosphors. They are also more stable and brighter than organic dyes, making them advantageous for applications requiring high stability and brightness over long periods, such as cell studies in biological research. Essentially, quantum dot lasers can provide finer control over the emission properties due to their size-dependent energy levels and have the potential for lower threshold currents and improved modulation speeds in comparison to conventional semiconductor lasers.