Poling-free integrated second-order nonlinear optics with evaporated organic thin films

Area of Science:

• Integrated photonics
• Nonlinear optics
• Materials science

Background:

• Second-order nonlinear photonics is crucial for advanced classical and quantum technologies.
• Existing materials face challenges in combining high nonlinear performance with scalable, CMOS-compatible fabrication.
• Vapor-deposited organic thin films offer potential for high nonlinearities without electric field poling.

Purpose of the Study:

• To demonstrate functional photonic devices using spontaneously oriented organic thin films.
• To overcome the speculative nature of translating these films into practical applications.
• To achieve efficient second-harmonic generation in integrated waveguides.

Main Methods:

• Fabrication of strip-loaded waveguides using vapor-deposited organic thin films.
• Harnessing the film's giant birefringence (Δn ≈ -0.2) for phase-matching.
• Utilizing TE00 to TM00 mode conversion for high modal overlap.

Main Results:

• Demonstration of phase-matched second-harmonic generation in strip-loaded organic waveguides.
• Achieved conversion efficiency comparable to thin-film lithium niobate devices.
• Established the viability of spontaneously oriented organics for nonlinear photonic integration.

Conclusions:

• Spontaneously oriented organic thin films are a promising material class for integrated photonics.
• These materials enable the integration of second-order nonlinear functionalities on diverse substrates.
• The demonstrated approach overcomes previous limitations in organic nonlinear photonics.