There is a great variety of different semiconductor lasers, spanning wide parameter regions and many different application areas:

• Small edge-emitting laser diodes generate a few milliwatts (or up to 0.5 W) of output power in a beam with high beam quality. They are used e.g. in laser pointers, in CD players, and for optical fiber communications.

• External cavity diode lasers contain a laser diode as the gain medium of a longer laser cavity. They are often wavelength-tunable and exhibit a small emission linewidth.

• Both monolithic and external-cavity low-power levels can also be mode-locked for ultrashort pulse generation.

• Broad area laser diodes generate up to a few watts of output power, but with significantly poorer beam quality.

• High-power diode bars contain an array of broad-area emitters, generating tens of watts with poor beam quality.

• High-power stacked diode bars contain stacks of diode bars for the generation of extremely high powers of hundreds or thousands of watts.

• Surface-emitting lasers (VCSELs) emit the laser radiation in a direction perpendicular to the wafer, delivering a few milliwatts with high beam quality.

• Optically pumped surface-emitting external-cavity semiconductor lasers (VECSELs) are capable of generating multi-watt output powers with excellent beam quality, even in mode-locked operation.

• Quantum cascade lasers operate on intraband transitions (rather than interband transitions) and usually emit in the mid-infrared region, sometimes in the terahertz region. They are used e.g. for trace gas analysis.