Photonic jet subwavelength etching using a shaped optical fiber tip

Area of Science:

• Photonics
• Laser Material Processing
• Nanofabrication

Background:

• Photonic jets (PJs) are highly directional, low-divergence beams generated by subwavelength dielectric structures.
• Conventional methods for generating PJs often rely on microspheres, which can be challenging to manipulate and integrate into processing systems.
• Subwavelength etching is crucial for advanced microelectronics and nanotechnology, requiring high precision and resolution.

Purpose of the Study:

• To demonstrate the generation of photonic jets (PJs) using a shaped optical fiber tip.
• To utilize these PJs for achieving subwavelength etchings on silicon wafers.
• To explore the feasibility of using a more manageable optical fiber system for PJ applications in laser processing.

Main Methods:

• A shaped-tip multimode silica optical fiber (100/140 μm) was employed to generate PJs.
• A near-infrared (1064 nm) Nd:YAG laser (30 W, 100 ns pulse duration) was used as the light source.
• The laser power was attenuated, requiring only 10% of the maximum output, and experiments were conducted in ambient air.
• Etching patterns on a silicon wafer were analyzed to determine feature sizes.

Main Results:

• Photonic jets were successfully generated in the vicinity of the shaped optical fiber tip, eliminating the need for microspheres.
• Subwavelength etchings with lateral feature sizes close to half the laser wavelength were achieved on silicon wafers.
• The process demonstrated efficient etching using a significantly reduced laser power (10% of 30 W).

Conclusions:

• Shaped optical fibers can effectively generate photonic jets for laser-based material processing.
• This technique offers a novel and practical approach for achieving high-resolution, subwavelength etchings.
• The use of optical fibers for PJ generation presents significant advantages for manipulation and broader application in industrial and scientific fields.