Enhanced nonlinear interaction in a microcavity under coherent excitation

Area of Science:

• Photonics
• Nonlinear Optics
• Materials Science

Background:

• High quality factor (Q) and small mode volume photonic crystal microcavities offer significant field enhancement for nonlinear interactions.
• Pulsed excitation in nonlinear microcavities causes frequency shifts due to nonlinear refractive index changes, limiting coupling efficiency and interaction duration.
• Preserving light localization throughout pulsed excitation is crucial for maximizing intra-cavity nonlinear effects.

Purpose of the Study:

• To experimentally demonstrate coherent excitation of a nonlinear microcavity for enhanced intra-cavity nonlinear interaction.
• To investigate the nonlinear behavior of a Silicon-based microcavity using tailored chirped pulses.
• To control intra-cavity light-matter interactions and nonlinear dynamics in microcavity-based optical devices.

Main Methods:

• Experimental demonstration of coherent excitation in a nonlinear microcavity.
• Utilized Silicon-based microcavities.
• Employed tailored positively chirped pulses for excitation and compared with Fourier-transform limited pulses.

Main Results:

• Achieved a factor of 2.5 increase in free carrier density generated by two-photon absorption using chirped pulses compared to Fourier-transform limited pulses.
• Observed an extended frequency blue-shift of the cavity resonance, reaching 19 times the linear cavity bandwidth.
• Demonstrated enhanced intra-cavity nonlinear interaction throughout the pulsed excitation.

Conclusions:

• Coherent excitation is an effective strategy to overcome limitations in pulsed nonlinear microcavity dynamics.
• Tailored chirped pulses significantly enhance nonlinear effects, such as free carrier generation and resonance frequency shifts.
• This approach offers a promising route for controlling and optimizing light-matter interactions in advanced optical devices.