Mode locking at terahertz frequencies using a distributed Bragg reflector laser with a sampled grating.

Area of Science:

• Optoelectronics
• Laser Physics
• Terahertz Science

Background:

• Mode-locked lasers are crucial for generating ultrashort optical pulses.
• Terahertz (THz) radiation has diverse applications but requires efficient, compact sources.
• Existing THz generation methods often face challenges in reproducibility and cost.

Purpose of the Study:

• To present a highly reproducible method for producing terahertz (THz) optical pulses.
• To demonstrate the use of a novel AlGaInInP laser design for THz generation.
• To explore the potential of these compact lasers for practical applications.

Main Methods:

• Utilized a mode-locked AlGaInAs/InP laser operating at 1.55 μm.
• Incorporated a sample grating distributed Bragg reflector for frequency selectivity.
• Employed distributed reflectors to relax fabrication tolerances and ensure cavity self-adjustment.

Main Results:

• Achieved nearly transform-limited pulse trains at 640 GHz and 1.28 THz.
• Demonstrated high controllability over THz pulse generation.
• Observed consistent performance across a wide range of drive conditions.

Conclusions:

• The developed laser offers a low-cost, compact, and reproducible source of THz radiation.
• This technology is poised to enable advancements in high-speed optical communication and THz imaging.
• The laser's design ensures robust and reliable operation, facilitating widespread adoption.