Home/Technical Glossary/Direct Diode Laser Direct Diode Laser A direct diode laser (DDL), as the name implies, is a laser originating from diodes without amplification in a crystal such as Nd:YAG. Since it is direct, the diode laser has a very simple construction and high conversion efficiency. It is MUCH more efficient than an Nd:YAG laser. The typical operating wavelength of a direct diode laser is 915 nm. Direct diode lasers are ideal for laser soldering and plastic laser welding applications.