Mode converter for high power, higher-order mode optical fiber amplifiers
AssigneeOFS Fitel, LLC
InventorJeffrey W Nicholson
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Abstract
A mode converter for use with a higher-order mode (HOM)-based fiber amplifiers takes the form of axicon-based configuration that is able to convert high power (tens of mW and higher) optical signals propagating in higher-order mode form into a diffraction-limited beam without experiencing the nonlinear effects (such as self-phase modulation) that are found when using a long-period grating (LPG) to create a diffraction-limited beam by performing mode conversion. The axicon may comprise a bulk optic device, a fiber-based device, or a GRIN-based configuration (where the refractive index profile of the GRIN element is formed to create a diffraction-limited signal).
Claims26
An optical system for providing conversion of a higher-order mode optical signal into a diffraction-limited beam, the optical system comprising:
- an optical waveguide for supporting the propagation of a higher-order mode optical signal;
- an axicon-based mode converter coupled to the output of the optical waveguide, the axicon-based mode converter including an axicon lensing element and a magnifying element, the magnifying element disposed between the optical waveguide and the axicon lensing element and the axicon lensing element formed to exhibit optical characteristics such that when the higher-order mode optical signal from the optical waveguide is applied as an input to the axicon-based mode converter, the axicon element performs mode conversion in a manner that creates a diffraction-limited output signal.
An HOM fiber-based optical transmission system, comprising:
- a section of doped HOM fiber including an input endface for receiving an optical signal to be amplified and an output endface for emitting the amplified optical signal;
- a long-period grating (LPG) coupled to the input endface of the doped HOM fiber for providing mode conversion between input signals propagating in a fundamental mode and a selected higher-order mode of the doped HOM fiber;
- and
- an axicon-based mode converter coupled to the output endface of the doped HOM fiber, the axicon-based mode converter including an axicon lensing element and a magnifying element, the magnifying element disposed at the input to the axicon lensing element and the axicon lensing element formed to exhibit optical characteristics such that the axicon-based mode converter transforms the selected higher-order mode optical signal at the output of the doped HOM fiber into a diffraction-limited output signal.
Dependencies are inferred from the claim text.