Integrated GaN photonic circuits on silicon (100) for second harmonic generation

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Semiconductor Devices

Background:

• Silicon photonics is limited by its centrosymmetric crystal structure, hindering second-order nonlinear optical effects.
• Gallium nitride (GaN) possesses strong second-order optical nonlinearity (χ2) and a wide transparency window.
• Heterogeneous integration offers a pathway to combine the advantages of different materials on a single platform.

Purpose of the Study:

• To demonstrate second-order optical nonlinearity in a silicon-based architecture.
• To achieve efficient and tunable second harmonic generation (SHG) using integrated GaN.
• To explore the potential of this platform for on-chip optical wavelength generation.

Main Methods:

• Heterogeneous integration of single-crystalline GaN on silicon (100) substrates.
• Fabrication of GaN microrings engineered for dual resonance at 1560 nm and 780 nm.
• Measurement of the second-order nonlinear susceptibility (χ2) and SHG efficiency.

Main Results:

• Demonstrated efficient, tunable second harmonic generation at 780 nm.
• Measured a high nonlinear susceptibility (χ2) of up to 16 ± 7 pm/V.
• Confirmed the dual resonance capability of the engineered GaN microrings.

Conclusions:

• Heterogeneously integrated GaN on silicon enables on-chip second-order optical nonlinearity.
• The platform is suitable for efficient, tunable SHG and other χ2-based frequency conversion processes.
• This approach provides a viable route for generating optical wavelengths from near-UV to far-infrared on-chip.