Blue laser versus red laser

Blue laser has mostly replaced the use of red laser in the area of data storage. At the beginning, the first types of blue lasers had many disadvantages. Initially, they were only gas lasers, which needed high currents and produced a huge amount of heat, therefore needing strong cooling.

After that, the first types of semiconductor blue lasers (or blue laser diodes) had a very short life (several hundred hours at the most), even if they worked at a very low temperature (needing almost absolute zero values - 00K - to work properly). But further development solved all these issues.

While the red and infrared lasers are usually based on GaAs (gallium arsenide), in case of blue lasers, the InGaN (indium gallium nitride, which has a violet color) and GaN (gallium nitride, which has a true-blue color) based ones are preferred .

The ZnSe (zinc selenide) based laser was gradually excluded from research, because of its high resistivity, high energy consumption and very small efficiency. The most efficient technology of building blue-lasers is using InGaN quantum wells to form the active medium.

The best known example of blue laser applications in storage data is the Blue-ray disc. The Blue-ray disc (or BD or BRD or Blu-ray) is an optical disc storage medium, which was designed to enhance the standard DVD format. If the standard DVD(Digital Video Disc) and CD (Compact Disc) use a red laser (for which the emitting light has a wavelength of 650nm and 780nm respectively), the BD uses a blue laser (with light emitting at a wavelength of 405nm).

The blue laser gave a higher data storage capacity and speed in case of Blu-ray disc (almost ten times bigger than DVD). The blu-ray was in competition with the HD DVD (High-Definition/Density DVD, which was also used for data storage and high-definition video and is now practically a defunct high-density optical disc format).

Even if both of these were capable of higher quality video and audio playback, and had rather equivalent levels of visual and audio quality (because both shared the same methods of encoding media onto disks with each other), the difference between them is consisting mainly in internet integration, usage control and enforcement, interactive capabilities and storage size. In case of the latter, a dual-layer Blu-ray holds 50 GB, while a HD DVD holds 30 GB at the most.

This, together with lower costs and better read/write speeds made Blu-ray the eventual winner of the competition with classical, red laser based data storage disks.