Electrically smoothing gain-switched optical pulses from a semiconductor laser diode.

Area of Science:

• Optics and Photonics
• Semiconductor Device Physics

Background:

• Gain-switched semiconductor laser diodes (LDs) typically produce optical pulses with a first-spike (FS) component and a quasi-steady-state (QSS) component.
• The FS component acts as spike noise, which can compromise stability and accuracy in sensing and detection applications.

Purpose of the Study:

• To develop and demonstrate a technique for smoothing optical pulse shapes from gain-switched LDs.
• To effectively eliminate or suppress the FS component without requiring post-processing.

Main Methods:

• Utilizing a stepped electric pulse technique to drive gain-switched semiconductor LDs.
• Employing rate-equation calculations to model and understand the underlying physics of the pulse shaping mechanism.

Main Results:

• The stepped electric pulse effectively eliminates or suppresses the FS component of the optical pulse.
• Rate-equation calculations validated the experimental findings, highlighting the role of a pre-pump phase.
• The pre-pump adjusts carrier density to near-threshold levels, suppressing FS generation and enabling faster transition to QSS mode.

Conclusions:

• The stepped electric pulse pump is a feasible and convenient method for smoothing optical pulse shapes from gain-switched semiconductor LDs.
• This technique enhances pulse quality for applications demanding high stability and accuracy, such as sensing and detection.