Synthetic complex superresolving pupil filter based on double-beam phase modulation

Area of Science:

• Optical Engineering
• Nanotechnology
• Laser Physics

Background:

• Reducing reflected stray light is crucial for high-resolution laser direct writing.
• Conventional complex superresolving pupil filters (CCSPF) often involve amplitude modulation, which can be inefficient.
• Phase-only filters offer a promising alternative for improved light manipulation.

Purpose of the Study:

• To develop a synthetic complex superresolving pupil filter utilizing phase-only modulation.
• To establish the equivalence between the proposed phase-only filter and CCSPFs.
• To demonstrate the effectiveness of the new filter for creating small focal spots in laser direct writing.

Main Methods:

• Designing a synthetic complex superresolving pupil filter using two phase plates.
• Replacing amplitude modulation with equivalent phase modulation.
• Establishing the theoretical equivalence between the proposed filter and CCSPFs for general designs.
• Conducting experimental validation.

Main Results:

• The proposed filter effectively reduces reflected stray light.
• Experimental results show a main lobe width of 0.86 times the Airy spot size.
• The filter enables the generation of a smaller focal spot compared to conventional methods.

Conclusions:

• The developed phase-only synthetic complex superresolving pupil filter is effective for laser direct writing.
• The filter achieves a sub-Airy spot size, enhancing resolution.
• This approach offers an efficient method for stray light reduction and superresolution imaging.