Toptica has introduced its new SHG pro series of frequency-converted diode lasers, a novel CW system with an output power of 2W at 589nm. The new DL RFA SHG pro features a linewidth of less than 1MHz and a mode-hop free tuning range of more than 10GHz, and is thus well suited to laser cooling of sodium. It presents a stable and easy-to-use alternative to the intricate dye lasers used previously for this application, as these required frequent maintenance and water cooling.
The DL RFA SHG pro is based on a tunable external-cavity diode laser (ECDL) in Toptica’s proven pro design at 1,178nm. The output of the ECDL is amplified within a novel polarisation-maintaining Raman fibre-amplifier (RFA), which preserves the spectral properties of the seed laser, particularly its narrow linewidth. Subsequently, the amplifier output is frequency-doubled in the SHG pro resonator to the target wavelength of 589nm. The system features an excellent beam profile and a high long-term power and frequency stability.
The DL RFA SHG pro is ideally suited for laser cooling applications and Bose-Einstein condensation of sodium atoms, and is also of particular interest for mixed-atom systems. Special versions of the laser with output powers up to 20W are also suitable for sodium-lidar, high-resolution microscopy, or laser guide star applications. The same technology can transferred to wavelengths between 560 and 640nm (e.g. 583nm for laser cooling of erbium), or extended to frequency-quadrupled systems between 280 and 310nm (e.g. 285nm for laser cooling of magnesium).