Novel liquid crystal photonic devices enabled by two-photon polymerization [Invited]

Area of Science:

• Photonics
• Materials Science
• Nanotechnology

Background:

• Liquid crystals (LCs) are crucial in photonic devices beyond displays, including adaptive lenses, optics, and sensors.
• Their utility stems from responsive behavior to electric fields, temperature, and light.
• Advancements in fabrication techniques enable the design of more sophisticated LC devices.

Purpose of the Study:

• To review recent advances in liquid crystal devices fabricated using two-photon polymerization (TPP)-based direct-laser writing.
• To demonstrate the capability of TPP in generating surface morphology for LC director alignment.
• To propose novel photonic device designs, such as ultra-broadband diffractive waveplates.

Main Methods:

• Description of the fundamental working principle of two-photon polymerization.
• Fabrication of surface morphologies to control LC director alignment on various substrates (planar, curvilinear, 3D volumes).
• Discussion of direct-laser writing on liquid crystal reactive mesogens.

Main Results:

• Successful demonstration of LC alignment on planar, curvilinear, and three-dimensional surfaces using TPP-generated anchoring energy.
• Proposal of a novel, ultra-broadband, twisted-nematic diffractive waveplate design.
• Overview of the current state and potential applications of direct-laser writing on LC reactive mesogens.

Conclusions:

• Two-photon polymerization is a powerful technique for fabricating sophisticated LC photonic devices.
• The method allows for precise control of LC alignment through surface morphology engineering.
• Future work needs to address challenges in fabrication yield and polymer relaxation for practical applications.