Characterizing power-dependent chirp dynamics of DML based on a time lens

Area of Science:

• Photonics
• Optical Communications
• Laser Physics

Background:

• Directly modulated lasers (DMLs) are crucial for short-reach optical interconnects.
• Chirp and chromatic dispersion (CD) in standard single-mode fiber (SSMF) cause signal distortion, limiting bandwidth.
• Accurate characterization of DML chirp dynamics is essential for system performance.

Purpose of the Study:

• To experimentally demonstrate a time-lens-based method for discriminably characterizing DML chirp coefficients.
• To dynamically observe DML chirp behavior concerning optical power and time.
• To quantify the adiabatic chirp coefficient (κ) and linewidth enhancement factor (α).

Main Methods:

• Development and implementation of a time-lens-based experimental setup.
• Discriminable measurement of chirp coefficients (κ and α) in DMLs.
• Dynamic observation of chirp characteristics under varying optical power and time.

Main Results:

• Achieved measurement ranges of up to 19.9 for α and 51 GHz/mW for κ.
• Demonstrated dynamic observation of DML chirp dynamics.
• Validated the method with a DML driven by 1.33 GHz electrical signals and optical powers from 1.2 mW to 3.6 mW.

Conclusions:

• The time-lens method provides accurate and dynamic characterization of DML chirp coefficients.
• This technique is vital for mitigating signal distortion and improving bandwidth in optical interconnects.
• The demonstrated measurement ranges are significant for practical DML applications.