CMOS-integrated GaN LED array for discrete power level stepping in visible light communications

Area of Science:

• Optoelectronics
• Integrated Photonics
• Digital Communications

Background:

• Micro-light-emitting diode (LED) arrays are crucial for optical communication systems.
• Achieving discrete optical output power levels is essential for efficient data modulation.
• Existing CMOS-integrated solutions require further development for advanced modulation schemes.

Purpose of the Study:

• To demonstrate a CMOS-integrated micro-LED array capable of generating discrete optical output power levels.
• To assess the linearity and data transmission capabilities of the micro-LED array.
• To explore the potential of the array for pulse amplitude modulation (PAM) and orthogonal frequency division multiplexing (OFDM).

Main Methods:

• Fabrication of a 16 × 16 individually addressable micro-LED array on a CMOS platform.
• On-off control of pixels using parallel logic signals.
• Driving selected groups of LEDs to produce discrete optical power levels for data transmission.
• Performance evaluation using PAM and OFDM, including linearity assessment and error-free transmission tests.

Main Results:

• Demonstrated error-free data transmission at 200 Mb/s using 4-pulse amplitude modulation (PAM) at 100 MSamples/s.
• Achieved 150 Mb/s with 8-PAM, requiring encoding to mitigate receiver baseline wander.
• Experimental proof-of-concept for discrete-level orthogonal frequency division multiplexing (OFDM) with a spectral efficiency of 3.96 bits/s/Hz.

Conclusions:

• The CMOS-integrated micro-LED array effectively generates discrete optical power levels suitable for high-speed data transmission.
• The array supports advanced modulation techniques like PAM and OFDM, demonstrating its versatility.
• This technology shows promise for future optical communication systems requiring integrated, high-performance light sources.