30 Gbit/s PAM4 transmission using an 8-GHz directly modulated multi-section laser

Area of Science:

• Photonics and Optical Communications
• Semiconductor Lasers
• Fiber Optic Networks

Background:

• Directly modulated lasers are crucial for optical communication systems.
• Achieving high data rates over extended fiber links requires lasers with low noise and chirp.
• Master-slave laser configurations offer potential for improved performance.

Purpose of the Study:

• To characterize a novel directly modulated multi-section laser with a master-slave configuration.
• To evaluate the laser's performance for optical access network applications.
• To demonstrate the laser's capability for high-speed data transmission.

Main Methods:

• Characterization of amplitude and phase noise.
• Measurement of relative intensity noise (RIN) and 3-dB linewidth.
• Demonstration of data transmission using Pulse Amplitude Modulation (PAM4 and PAM8).
• Testing transmission over various single-mode fiber lengths (25 km, 50 km, 75 km).

Main Results:

• Relative intensity noise (RIN) around -150 dB/Hz.
• 3-dB linewidth of approximately 3 MHz.
• Successful unamplified 30 Gbit/s C-band transmission over 25 km and 50 km using PAM4.
• Successful amplified 30 Gbit/s PAM4 and PAM8 transmission over 75 km.
• Chirp reduction achieved through external injection locking.

Conclusions:

• The novel laser demonstrates excellent noise and linewidth performance.
• External injection locking effectively reduces chirp, enhancing transmission capabilities.
• The laser is suitable for high-speed optical access networks, supporting 30 Gbit/s transmission over 75 km.