Improving grating duty cycle uniformity: amplitude-splitting flat-top beam laser interference lithography.

Area of Science:

• Optics and photonics
• Materials science
• Nanofabrication

Background:

• Grating fabrication is crucial for diffraction control.
• Duty cycle uniformity is a key parameter affecting grating performance.
• Conventional methods face limitations in uniformity and energy efficiency.

Purpose of the Study:

• To develop an improved grating fabrication technique for enhanced duty cycle uniformity.
• To analyze the relationship between beam irradiance and grating duty cycle uniformity.
• To demonstrate a practical system for large-area, uniform grating manufacturing.

Main Methods:

• Developed an amplitude-splitting flat-top beam interference lithography technique.
• Investigated the impact of exposure beam irradiance on duty cycle uniformity.
• Experimentally realized the fabrication system with controlled irradiance.

Main Results:

• Grating duty cycle nonuniformity is maintained below ±2% when beam irradiance nonuniformity is less than 20%.
• Experimental system achieved an incident beam irradiance nonuniformity of 21%.
• Fabricated gratings exhibited a full-aperture duty cycle nonuniformity of less than ±3%.

Conclusions:

• Amplitude-splitting flat-top beam interference lithography significantly improves grating duty cycle uniformity.
• The technique offers reduced energy loss compared to conventional apodization methods.
• This method is highly suitable for large-area, cost-effective manufacturing of uniform gratings.