Manufacturing high-efficiency, high damage threshold diffraction gratings with lift-off processing
- Cornell Univ., Ithaca, NY (United States); Lawrence Livermore National Lab., CA (United States)
High-efficiency, high damage threshold diffraction gratings fabricated out of multilayers of dielectric materials are needed for the application of chirped-pulse amplification (CPA) in the Petawatt Laser Project. The underlying multilayers are deposited onto a flat substrate by standard e-beam evaporation. The grating structures themselves, however, can either be etched into a plane layer or deposited between a photoresist grating mask which is subsequently lifted off. The latter procedure, although more easily applied to large apertures, requires high-aspect ratio, vertical sidewall photoresist grating masks with, preferably, an overhanging structure to facilitate liftoff. By varying factors in each processing step, sample gratings were fabricated and then characterized. Using a high-contrast profile photoresist (AZ7710), we have been able to create grating masks with both vertical sidewalls and high-aspect ratios (>4.5). We have also had some encouraging preliminary results in making overhanging structures by including a pre-development hlorobenzene soak in the processing steps. Once these samples are deposited with an oxide and the grating masks lifted off to create the final grating, a more definitive processing method can be developed based on the results.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 576735
- Report Number(s):
- UCRL-ID--114972-5; ON: DE97009099
- Country of Publication:
- United States
- Language:
- English
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