Diode Laser Systems Emitting in the Blue and UV Spectral Range

Diode laser based light sources with an emission in the blue and UV spectral range are developed for Raman spectroscopy using two concepts. The laser emission of a distributed feedback (DFB) diode laser at 976 nm is frequency converted to 488 nm. These compact excitation light sources are realized using microoptical components for portable Raman systems.
In order to address the UV spectral range commercial available diode lasers at 445 nm are used as gain media in an external laser cavity. This wavelength stabilized emission is ideally suited for frequency doubling.

SHG microsystem light source at 488 nm
SHG microsystem light source at 488 nm

Functional principle

The emission of a wavelength stabilized diode laser is focused into a crystal for non-linear frequency conversion using microoptics. For an efficient generation of laser radiation in the visible spectral range a waveguide crystal is used. This provides 50 mW at 488 nm using moderate optical power of a DFB laser. The light source is mounted on a conduction cooled package with a footprint of 25 mm x 25 mm.

Applications

  • Excitation light sources for Raman spectroscopy and Shifted Excitation Raman Difference Spectroscopy – SERDS

Wavelength

  • 488 nm (SHG)
  • 445 nm (ECDL)

Technology and Mounting

  • Semiconductor structures with MOVPE
  • Laser structures with internal gratings
  • Active alignments on a micro-optical bench
  • Non-linear frequency conversion
  • Diode laser in external cavity

Typical data

  • SHG microsystem light source with 50 mW at 488 nm and 25 % conversion efficiency
  • ECDL with 400 mW at 445 nm

The development of these diode lasers is funded by the Einstein Foundation Berlin in the project HautScan (funding period: 01.08.2012 - 31.07.2015).