Second-harmonic-generation-based technique for examining laser diode wavelength dynamics in the μs to ms range

Area of Science:

• Optics and Photonics
• Laser Physics
• Spectroscopy

Background:

• Accurate wavelength measurement is crucial in optics and photonics.
• Existing techniques have limitations in resolution (nanometers) or measurement speed (kHz).
• Fast wavelength dynamics of laser diodes are not well-characterized with current methods.

Purpose of the Study:

• To present a novel, versatile technique for measuring fast wavelength dynamics of laser diodes.
• To achieve high resolution and high measurement rates for wavelength analysis.
• To enable investigation of phenomena like mode-hop behavior during pulsed operation.

Main Methods:

• Utilized second-harmonic generation (SHG) for wavelength measurement.
• Employed a nonlinear crystal and photodetectors for signal detection.
• Focused on a simple yet highly versatile experimental setup.

Main Results:

• Demonstrated a wavelength resolution of 0.7 picometers (pm).
• Achieved a measurement rate in the megahertz (MHz) range.
• Successfully captured wavelength changes of a laser diode during a single pulse.

Conclusions:

• The SHG-based technique offers significant improvements in both wavelength resolution and measurement speed.
• This method overcomes limitations of existing wavelength measurement devices.
• The technique is suitable for studying rapid spectral changes in laser diodes, such as mode hops.