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Vladimir G Lemberg, Daryl Wong, Saidur Rahaman, Hong Fu; A Novel Femtosecond Laser Platform enabled by Hollow Core Photonics Crystal Fiber. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5766.
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© ARVO (1962-2015); The Authors (2016-present)
Femtosecond lasers have been increasingly and widely used in various ophthalmic surgical procedures. The use of conventional optical fiber based beam delivery for ultrashort laser pulses are limited due to the optical fibers dispersion. The purpose of this study is to explore the new opportunities to build flexible beam delivery based on the recent advances in development of the hollow-core photonic crystal fibers.
In this study we evaluated the properties of Kagome hollow-core photonic crystal fiber PMC-C-Yb-7C to be used to deliver the ultrashort femtosecond laser pulses to the target tissue. We demonstrated feasibility to build tabletop and handheld flexible beam configurations and performed variety of the corneal cuts. We used modular approach to achieve flexibility and mechanical stability. In the tabletop version the low NA fiber output laser beam (pulse duration 150 fs, wavelength 1030 nm, repetition rate 10 MHz) was re-collimated and delivered to the scanning system with high numerical aperture (NA 0.6) focusing objective. We also demonstrated the feasibility of the ophthalmic surgical handpiece with the dual axis scanning MEMS mirror and variable focus objective.
The design of the fiber coupling module with the variable NA optical system allowed us to achieve the high (more than 94%) coupling efficiency. We chose the Kagome type hollow-core photonic crystal fiber with close to zero dispersion (~1 fs/nm/meter) and (less than 2.5%) transmission losses at 1030 nm wavelength and was able to deliver the femtosecond laser pulses with virtually no pulse width broadening and low transmission losses (attenuation of -0.05 dB per meter at 1030 nm). We were able to perform variety of the corneal cuts (corneal flap, intrastromal cut and lenticule extraction) using the flexible delivery configuration.
The unique properties of the air-core photonic crystal fibers (close to zero dispersion at the design wavelength, absence of Fresnel reflections from the fiber-end faces, high damage threshold and low transmission and bend losses) allowed us to developed and demonstrated tabletop and handheld flexible beam delivery configurations for the novel femtosecond laser technologies.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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