Non-invasive characterization of cascaded SOAs on InP-based photonic integrated circuits

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Semiconductor Device Physics

Background:

• Semiconductor Optical Amplifiers (SOAs) are crucial for optical switching networks, offering loss compensation and fast reconfiguration.
• Characterizing individual SOAs in integrated circuits is difficult without adding components that increase power consumption.
• Optimizing SOA chain performance requires accurate gain response data for each amplifier.

Purpose of the Study:

• To develop a non-invasive pre-monitoring technique for N-cascaded SOAs on Indium Phosphide (InP) chips.
• To assess SOA gain and inter-stage path losses without disrupting the optical network.
• To enable feasible and non-disruptive characterization of SOAs in photonic integrated circuits (PICs).

Main Methods:

• Utilizing each SOA as both an optical amplifier (OA) and photodetector (PD) by considering both forward and backward light propagation.
• Experimentally demonstrating the method on a PIC with 3-cascaded SOAs within an optical neural network chip.
• Retrieving inter-SOA losses and noise response to derive SOA gain curves.

Main Results:

• Successfully demonstrated non-invasive characterization of cascaded SOAs on a PIC.
• Experimental results accurately retrieved inter-SOA losses and noise.
• Obtained SOA gain curves showed excellent agreement with reference measurements (<1.0 dB gain error, <1.5 dB noise error).

Conclusions:

• The proposed non-invasive method provides accurate characterization of cascaded SOAs.
• This technique effectively measures SOA gain and path losses, crucial for network optimization.
• The results facilitate automated, non-invasive screening of SOAs in large-scale PICs and packaged devices.