Second-harmonic radiation from an AlGaAs laser and its application for absorption spectroscopy

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Laser diodes are crucial light sources.
• Nonlinear optical phenomena, like second-harmonic generation (SHG), can enhance laser capabilities.
• Exploring SHG in compact laser diode systems is of interest for novel applications.

Purpose of the Study:

• To investigate the feasibility and characteristics of second-harmonic radiation generation from commercial laser diodes.
• To determine the temperature dependence of the conversion efficiency for this process.
• To explore potential applications of the generated second-harmonic radiation.

Main Methods:

• Experimental observation of second-harmonic radiation from multiple commercial laser diodes.
• Measurements conducted across a temperature range of 130 K to 310 K.
• Characterization of spectral width and conversion efficiency.
• Application of the generated radiation as a spectroscopic light source.

Main Results:

• Second-harmonic radiation with picowatt power was successfully generated from milliwatt-output laser diodes.
• No significant temperature dependence was observed for the conversion efficiency.
• The spectral width of the second-harmonic radiation was found to be limited by the fundamental laser diode's spectral width.
• The internal second-harmonic radiation was utilized to observe absorption lines of potassium and aluminum.

Conclusions:

• Commercial laser diodes can serve as sources for internal second-harmonic generation.
• The conversion efficiency is largely independent of temperature within the tested range.
• This SHG process offers a viable route for developing compact spectroscopic light sources.