Photonic Integrated Circuits (PICs) — chips that manipulate light instead of electrons, enabling high-bandwidth, low-power data communication and sensing by integrating optical components on semiconductor substrates.

Why Photonics?

• Electrical wires: Bandwidth limited by RC delay, power grows with distance and data rate
• Optical: Speed of light, no RC delay, bandwidth independent of distance
• At >100 Gbps per lane, optics becomes more efficient than copper

Key Components on a PIC

• Waveguide: Guides light on-chip (analogous to a wire for electrons)
• Modulator: Converts electrical signal to optical signal (E/O)
• Photodetector: Converts optical back to electrical (O/E)
• Multiplexer/Demultiplexer: Combine/split multiple wavelengths (WDM)
• Coupler/Splitter: Combine or divide optical power

Silicon Photonics

• Use standard CMOS fabs to build optical components in silicon
• Silicon is transparent at telecom wavelengths (1310/1550 nm)
• Co-package with electronics for minimum latency
• Providers: Intel, Cisco (Acacia), Broadcom, GlobalFoundries

Applications

• Data center interconnects (400G, 800G, 1.6T Ethernet)
• AI cluster networking (GPU-to-GPU communication)
• LiDAR for autonomous vehicles
• Biosensors and medical diagnostics

Photonics is transitioning from fiber optics into the chip — it's the technology that will enable the next order-of-magnitude increase in data center bandwidth.