Free carrier induced dark pulse generation in microresonators

Area of Science:

• Nonlinear Optics
• Quantum Optics
• Photonics

Background:

• Microresonators are key components in nonlinear optics for generating optical frequency combs.
• Generating ultrashort optical pulses, such as dark pulses, is crucial for various applications.
• Existing methods for dark pulse generation often involve complex setups or specific laser requirements.

Purpose of the Study:

• To theoretically demonstrate a novel mechanism for dark pulse excitation in normal dispersion microresonators.
• To explore the role of free carrier dispersion and absorption in dark pulse formation.
• To investigate the feasibility of generating dark pulses using a fixed-frequency laser.

Main Methods:

• Theoretical modeling of dark pulse excitation in microresonators.
• Exploiting free carrier dispersion and absorption effects arising from multi-photon absorption (three- and four-photon regimes).
• Investigating the influence of external reverse bias on free carrier lifetime.

Main Results:

• Demonstrated a novel mechanism for dark pulse generation in normal dispersion microresonators.
• Showcased dark pulse generation in both three- and four-photon absorption regimes.
• Confirmed the feasibility of direct dark pulse generation with a fixed-frequency laser.
• Analyzed the temporal and spectral dynamics of the generated dark pulses.

Conclusions:

• Established a reliable and simplified method for dark pulse generation in microresonator systems.
• Paved the way for simplified controlling and tuning techniques for dark pulse and Kerr microcomb generation.
• Highlighted the potential of free carrier effects in designing advanced optical pulse generation schemes.