Tunable single-frequency diode lasers consist of a laser diode and a frequency selective element like a grating, which controls the emission frequency. TOPTICA offers diode laser systems with an external grating (ECDL) as well as systems with a frequency-selective element integrated within the semiconductor structure itself (DFB diodes). These systems are available for individual wavelengths between 369 nm and 3500 nm, and provide tunable, narrow-linewidth emission.