Diode Laser: Edge Jerfey van Weelden 09-04-2009

General Information Most common type of laser Low cost (mass product) In 2004, 733 million compared to 131.000 other type lasers Low cost (mass product) Use electrical current to power the laser Light diode laser many different properties Power Wavelength

Semiconductor laser Semiconductor laser have a p-n junction. Recombination in juction region Resistance high in junction region Homojunction single junction of the n- and p- doped materials high heat dissipation, not practical

Structure diode laser: edge Double hetero structure Two types of semiconductors Potential barrier Edge, light emitted parallel to surface junction current through metal contact Edge cleaved

Bandedge diagram hetero structure Active region Forward bias Holes and electrons confined in active region

Properties Higher bias → higher output power Different materials semiconductor → Different wavelengths Continuous/pulsed bias → continuous/pulsed output Small size

Applications Barcode readers Pumping other lasers Laser pointers Dvd/cd-rom Dentistry (soft tissue procedures)

Recent experiment The Effects of a Diode Laser (810 nm) on Pigmented Guinea-pig Skin E.M. Procaccini, G. Riccio, M. Bellocci, C. Di Martino and G. Monfrecola 2001 Only pigmented area’s damaged absorbed by melanin treating pigmented lesions without damaging the surrounding non-pigmented organelles