Efficient second harmonic generation in nanophotonic GaAs-on-insulator waveguides

Area of Science:

• Photonics
• Materials Science
• Quantum Optics

Background:

• Nonlinear frequency conversion is vital for next-generation optical systems.
• Portable metrology and quantum networks require highly efficient second-order nonlinear devices.
• Nanophotonic waveguides offer intense nonlinear interactions for enhanced device performance.

Purpose of the Study:

• To demonstrate high-efficiency second harmonic generation (SHG) in GaAs-on-insulator waveguides.
• To optimize waveguide design for efficient modal phase-matching and minimize propagation loss.
• To investigate the potential for integrated photonic devices in quantum applications.

Main Methods:

• Fabrication of GaAs-on-insulator waveguides using optimized wafer-bonding.
• Minimization of propagation loss and surface-state absorption.
• Design of waveguide geometry for modal phase-matching and tolerance to fabrication variations.

Main Results:

• Achieved unprecedented SHG efficiency of 40 W^-1 in a single-pass device.
• Demonstrated efficient conversion of a 2.0 µm pump to a 1.0 µm signal over 2.9 mm.
• Observed wide signal bandwidth (148 GHz) and tunable operation over a 45 °C range.

Conclusions:

• GaAs-on-insulator waveguides provide a highly efficient platform for nonlinear frequency conversion.
• The demonstrated device enables integrated self-referenced frequency combs and entangled photon pair generation.
• High uniformity fabrication on 76 mm wafers indicates scalability for practical applications.