All-optical amplitude-phase transmultiplexing of RZ-OOK and RZ-BPSK to RZ-QPSK by polarization-insensitive XPM using...

Area of Science:

• Optical Communications
• Nonlinear Optics
• Semiconductor Waveguides

Background:

• High-speed optical communication systems require efficient multiplexing techniques.
• Polarization sensitivity remains a challenge in optical signal processing.
• AlGaAs waveguides offer potential for nonlinear optical applications.

Purpose of the Study:

• To demonstrate polarization-insensitive phase-transmultiplexing (PI-PTM) for the first time.
• To convert two 10-Gb/s signals into a 20-Gb/s RZ-QPSK signal.
• To investigate the performance in a passive, birefringent AlGaAs waveguide.

Main Methods:

• Utilized polarization-insensitive cross-phase modulation (PI-XPM).
• Employed a passive, birefringent AlGaAs waveguide.
• Input signals: 10-Gb/s RZ-OOK pump and 10-Gb/s RZ-BPSK probe.
• Output signal: 20-Gb/s RZ-QPSK.

Main Results:

• Successfully demonstrated PI-PTM for the first time.
• Achieved conversion of two 10-Gb/s signals to a 20-Gb/s RZ-QPSK signal.
• Measured pre-amplified receiver sensitivity penalties for DQPSK-detection: ≈ 2.5 dB (in-phase) and ≈ 4.9 dB (quadrature).
• Penalties were relative to an FPGA-precoded RZ-DQPSK baseline under specific conditions (≈ 12 nm pump-probe detuning, scrambled probe polarization, off-axis pump launch).

Conclusions:

• Polarization-insensitive phase-transmultiplexing is feasible in AlGaAs waveguides.
• The demonstrated technique shows promise for future high-capacity optical networks.
• Further optimization may reduce receiver sensitivity penalties.