Optical parametric generation of a mid-infrared continuum in orientation-patterned GaAs

Area of Science:

• Nonlinear Optics
• Mid-Infrared Photonics
• Semiconductor Materials

Background:

• Generating ultrabroadband mid-infrared (MIR) light sources is crucial for various spectroscopic and sensing applications.
• Traditional methods often involve complex setups or limited spectral ranges.
• Orientation-patterned semiconductors offer a promising platform for efficient nonlinear optical processes.

Purpose of the Study:

• To demonstrate the generation of an ultrabroad MIR continuum using optical parametric generation (OPG).
• To investigate the performance of orientation-patterned gallium arsenide (OP-GaAs) for MIR continuum generation.
• To characterize the spectral bandwidth, efficiency, and threshold of the OPG process.

Main Methods:

• Employed single-pass optical parametric generation (OPG) in an all-epitaxially-grown OP-GaAs crystal.
• Utilized picosecond pulses (1 ps) with energies up to 2 microJ and wavelengths between 3.1-3.3 microm for pumping.
• Characterized the generated spectrum using optical measurements, determining the bandwidth at 20 dB below the peak.

Main Results:

• Achieved an ultrabroad MIR continuum spanning over an octave, from 4.5 to 10.7 microm (measured at -20 dB).
• Observed a low OPG threshold of 55 nJ pump energy.
• Demonstrated a high slope efficiency of 51% near threshold and a maximum external conversion efficiency of 15%.

Conclusions:

• OP-GaAs is a highly effective material for generating ultrabroad MIR continua via OPG.
• The demonstrated OPG process offers a compact and efficient method for MIR light generation.
• The generated ultrabroadband MIR spectrum has significant potential for advanced spectroscopic and photonic applications.