Long-reach 60-GHz MMWoF link with free-running laser diodes beating

Area of Science:

• Optical communications
• Wireless networking
• Signal processing

Background:

• Millimeter-wave over fiber (MMWoF) links are crucial for high-bandwidth wireless access.
• Traditional MMWoF systems often require complex local oscillator (LO) setups, increasing cost and complexity.
• Achieving stable and high-speed data transmission over extended fiber links remains a challenge.

Purpose of the Study:

• To demonstrate a novel local-oscillator-free MMWoF link operating at the 60-GHz band.
• To enable high-speed data transmission over long-reach fiber and free-space links.
• To simplify MMWoF system architecture by eliminating the need for LOs and dual-mode carriers.

Main Methods:

• Utilizing mutually incoherent laser carriers for optical heterodyne millimeter-wave generation.
• Employing a wavelength-locked colorless laser diode (CLD) modulator for direct data encoding.
• Implementing square-law power envelope detection at the receiver for self-down-conversion.

Main Results:

• Successful transmission of 16.5-Gbit/s 32-QAM OFDM data over 50 km of single-mode fiber and 3 m of free space.
• Achieved a bit error rate of 3.8 × 10⁻³, error vector magnitude of 12%, and SNR of 18.4 dB.
• Demonstrated multi-channel capability, supporting 11 DWDM channels at 16.5 Gbit/s per channel.

Conclusions:

• The proposed MMWoF architecture effectively eliminates the need for local oscillators, simplifying system design.
• The system exhibits immunity to carrier frequency fluctuations and clock jitter, ensuring stable down-conversion.
• This technology offers a promising solution for future high-capacity, cost-effective wireless access networks and DWDM-PON applications.