Passive Fibers
Author: the photonics expert Dr. Rüdiger Paschotta (RP)
Definition: optical fibers without laser-active dopants in the fiber core
Category: 
Related: Tutorial on Passive Fiber OpticsMode Structure of a Multimode FiberDispersion Engineering for Telecom FibersNonlinear Pulse Compression in a FiberNumerical Experiments With Soliton Pulses in FibersCollision of Soliton Pulses in a FiberSoliton Self-frequency Shift in Glass FibersSoliton Pulses in a Fiber Amplifieractive fibersfiber optics
Opposite term: active fibers
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DOI: 10.61835/qie Cite the article: BibTex BibLaTex plain textHTML Link to this page! LinkedIn
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What are Passive Optical Fibers?
Passive fibers are optical fibers without laser-active dopants in the fiber core. That usually implies that they can only passively transmit light, with some propagation losses and without amplification of the optical power. In some cases, however, nonlinear amplification mechanisms based on stimulated Raman scattering or the Kerr nonlinearity occur.
Passive fibers can be separated into many specific categories:
- by fiber materials: glass fibers, single-crystal fibers, polycrystalline fibers (→ mid-infrared fibers), silica fibers, fluoride fibers, plastic optical fibers
- by fiber designs and physical principles of light guiding: step-index fibers, graded-index fibers, photonic crystal fibers, photonic bandgap fibers, hollow-core fibers, large-core fibers, tapered fibers, nanofibers
- by their guiding properties: single-mode fibers, polarization-maintaining fibers, single-polarization fibers, few-mode fibers, multimode fibers, large mode area fibers, dispersion-shifted fibers, dispersion-decreasing fibers
- by the spectral region: near-infrared fibers, mid-infrared fibers, UV fibers
- by their application areas: delivery fibers, telecom fibers, imaging fibers (e.g. as fiber bundles), sensor fibers (→ fiber-optic sensors)
Compared with active fibers, passive fibers generally exhibit lower propagation losses and are available at lower cost.
Fibers may be equipped with fiber connectors and protective materials to form fiber cables.
Passive Fiber Optics
This is a comprehensive introduction to fiber optics, focusing on passive (non-amplifying) fibers. It explains basic principles as well as practical aspects.
Mode Structure of a Multimode Fiber
We explore various properties of guided modes of multimode fibers. We also test how the mode structure of such a fiber reacts to certain changes in the index profile, e.g. to smoothing of the index step.
Dispersion Engineering for Telecom Fibers
We explore different ways of optimizing refractive index profile for specific chromatic dispersion properties of telecom fibers, resulting in dispersion-shifted or dispersion-flattened fibers. This also involves automatic optimizations.
Nonlinear Pulse Compression in a Fiber
We explore how we can spectrally broaden light pulses by self-phase modulation in a fiber and subsequently compress the pulses using a dispersive element. A substantial reduction in pulse duration by more than an order of magnitude is easily achieved, while the pulse quality is often not ideal.
Numerical Experiments With Soliton Pulses in Fibers
We investigate various details of soliton pulse propagation in passive fibers, using numerical simulations.
Collision of Soliton Pulses in a Fiber
We let two soliton pulses collide in a fiber. Surprisingly, they survive such collisions, even if we involve solitons of higher order.
Soliton Self-frequency Shift in Glass Fibers
We numerically simulate the soliton self-frequency shift, which is caused by stimulated Raman scattering. Influences like higher-order dispersion are found to be quite relevant.
Soliton Pulses in a Fiber Amplifier
We investigate to which extent soliton pulses could be amplified in a fiber amplifier, preserving the soliton shape and compressing the pulses temporally.
Frequently Asked Questions
This FAQ section was generated with AI based on the article content and has been reviewed by the article’s author (RP).
What is a passive optical fiber?
A passive optical fiber is a fiber without laser-active dopants in its core. It is designed to passively transmit light, typically with some propagation losses and without amplification of the optical power.
Can passive fibers amplify light?
Generally, they cannot, but in some cases, nonlinear amplification can occur through mechanisms like stimulated Raman scattering or the Kerr nonlinearity.
How are passive fibers different from active fibers?
Compared with active fibers, passive fibers typically exhibit lower propagation losses and are less expensive.
How can passive optical fibers be categorized?
Passive fibers can be classified based on various criteria, including their material (e.g., silica, fluoride, plastic), design (e.g., step-index, photonic crystal), guiding properties (e.g., single-mode, multimode), and application area.