[Paper Review] High Pressure Gases in Hollow Core Photonic Crystal Fiber:A New Nonlinear Medium

Mohiudeen Azhar, G. K. L. Wong+3 more|arXiv (Cornell University)|Oct 12, 2012

Photonic Crystal and Fiber Optics12 references3 citations

TL;DR

This paper proposes using high-pressure noble gases (e.g., argon) in kagome-style hollow-core photonic crystal fibers as a highly tunable, low-loss nonlinear medium. By pressurizing the gas from 1 to 150 bar, the effective Kerr nonlinearity increases over 100-fold, reaching 15% of bulk silica, while group velocity dispersion becomes widely tunable without Raman scattering, enabling clean, controlled studies of nonlinear effects like soliton-dispersive wave interactions with a fixed-frequency laser.

ABSTRACT

The effective Kerr nonlinearity of hollow-core kagome-style photonic crystal fiber (PCF) filled with argon gas increases over 100 times when the pressure is increased from 1 to 150 bar, reaching 15 % of that of bulk silica glass, while the zero dispersion wavelength shifts from 300 to 900 nm. The group velocity dispersion of the system is uniquely pressure-tunable over a wide range while avoiding Raman scattering : absent in noble gases and having an extremely high optical damage threshold. As a result, detailed and well controlled studies of nonlinear effects can be performed, in both normal and anomalous dispersion regimes, using only a fixed-frequency pump laser. For example, the absence of Raman scattering permits clean observation, at high powers, of the interaction between a modulational instability side-band and a soliton created dispersive wave. Excellent agreement is obtained between numerical simulations and experimental results. The system has great potential for the realisation of reconfigurable supercontinuum sources, wavelength convertors and short-pulse laser systems.

Motivation & Objective

• To develop a reconfigurable, low-loss nonlinear medium for all-optical signal processing.
• To overcome limitations of solid-core fibers, such as Raman scattering and fixed dispersion, in high-power nonlinear experiments.
• To enable precise, pressure-tunable control of group velocity dispersion across normal and anomalous regimes.
• To facilitate clean observation of complex nonlinear effects, such as soliton-dispersive wave interactions, without background noise from Raman scattering.
• To demonstrate a platform suitable for supercontinuum generation, wavelength conversion, and ultrafast pulse systems.

Proposed method

• Filling kagome-style hollow-core photonic crystal fibers with noble gases (e.g., argon) at pressures from 1 to 150 bar.
• Measuring the effective Kerr nonlinearity as a function of gas pressure using a fixed-wavelength pump laser.
• Monitoring the zero-dispersion wavelength shift from 300 nm at 1 bar to 900 nm at 150 bar.
• Employing numerical simulations based on the nonlinear Schrödinger equation to model pulse propagation and nonlinear dynamics.
• Using a fixed-frequency laser to excite nonlinear effects across both normal and anomalous dispersion regimes.
• Leveraging the high optical damage threshold and absence of Raman scattering in noble gases to enable high-power experiments.

Experimental results

Research questions

• RQ1 Can gas pressure in hollow-core photonic crystal fibers be used to actively tune the group velocity dispersion over a wide range?
• RQ2 How does increasing gas pressure affect the effective Kerr nonlinearity in hollow-core PCFs?
• RQ3 Can nonlinear effects such as modulational instability and soliton formation be observed cleanly without Raman background in noble gas-filled fibers?
• RQ4 To what extent does the system's nonlinearity approach that of bulk silica glass under high pressure?
• RQ5 Can this platform enable reconfigurable supercontinuum generation and wavelength conversion with a single-frequency laser source?

Key findings

• The effective Kerr nonlinearity of argon-filled kagome PCF increases over 100 times when pressure is raised from 1 to 150 bar.
• At 150 bar, the effective nonlinearity reaches 15% of that of bulk silica glass, enabling strong nonlinear interactions.
• The zero-dispersion wavelength shifts from 300 nm at 1 bar to 900 nm at 150 bar, enabling tuning across both normal and anomalous dispersion regimes.
• Raman scattering is absent in noble gases, allowing clean observation of nonlinear interactions such as soliton-dispersive wave coupling at high powers.
• Excellent agreement is observed between experimental results and numerical simulations based on the nonlinear Schrödinger equation.
• The system demonstrates strong potential for reconfigurable supercontinuum sources, wavelength converters, and short-pulse laser systems.