All-fiber sixth-harmonic generation of deep UV

Area of Science:

• Nonlinear Optics
• Fiber Optics
• Photonics

Background:

• Generating deep ultraviolet (DUV) light efficiently is crucial for various scientific and industrial applications.
• Traditional methods for DUV generation often involve complex bulk optics and limited material choices.
• Silica glass, a common optical material, has a low third-order nonlinear susceptibility, posing challenges for efficient nonlinear processes.

Purpose of the Study:

• To demonstrate a fully fiberized system for deep ultraviolet (DUV) generation.
• To achieve efficient harmonic generation from a 1550 nm laser source using cascading nonlinear processes.
• To overcome the limitations of silica glass's low nonlinear susceptibility.

Main Methods:

• Simulated and experimentally demonstrated cascading second- and third-harmonic generation (SHG and THG).
• Utilized a periodically poled silica fiber and an optical sub-micron diameter fiber.
• Harnessed intermodal phase matching in optical microfibers and a permanent nonlinear susceptibility (χ(2)) induced via thermal poling.

Main Results:

• Achieved efficient deep ultraviolet (DUV) generation from a 1550 nm laser source.
• Demonstrated successful cascading of second- and third-harmonic generation within the fiberized system.
• Observed efficient nonlinear processes despite the inherent low third-order nonlinear susceptibility of silica glass.

Conclusions:

• A fully fiberized system can effectively generate deep ultraviolet (DUV) light through cascaded nonlinear processes.
• Intermodal phase matching in microfibers combined with thermally poled silica enables efficient harmonic generation.
• This approach offers a viable pathway for DUV generation in compact and robust fiber-based systems.