Semiconductor lasers

Invented in the 1960s, semiconductor lasers - or, to be more precise, semiconductor laser diodes - have now reached a level of technological maturity that guarantees their ubiquitous use in a wide range of applications. While fiber communications were initially the main driving force behind their development, other applications such as reading and storing information on optical discs (CDs, DVDs) or optical pumping of power lasers have taken over.

This maturity is the fruit of spectacular progress in both the design and adaptation of structures to their intended application, and in the mastery of their production technology, not forgetting the "packaging" aspect, which is a major factor in their cost.

Thanks to our expertise in thin-film semiconductor manufacturing, we can now produce p-n junction diodes covering emission wavelengths ranging from blue, for future high-resolution DVD players and recorders (Blu-ray Disc or HD DVD standards), to near-infrared (1.5 µm) for long-distance optical communications.

A wide range of structures (edge-emitting ribbon lasers, surface-emitting VCSEL lasers) and oscillating structures, Fabry-Perot cavities or grating cavities (DFB), offer a wide variety of choices for applications. Threshold currents, emission powers, energy yields, radiation patterns and spectral purity are all properties that can be optimized by configuring the structure's geometric parameters and material compositions.

Packaging the laser in an enclosure containing the electrical and optical interfaces with the external environment is also vital to facilitate its implementation in its system environment. Today, this involves the development of miniature modules integrating several electronic modulation and emission control functions. Standardization initiatives currently underway on these modules are contributing to a significant reduction in their cost.

Last but not least, these lasers continue to benefit from the results of major research and development projects that have improved performance, created new functions and opened up new applications.

This dossier presents the state of the art of these laser sources. Some theoretical aspects are recalled, while others refer the reader to previous books or dossiers published by Techniques de l'Ingénieur.