TIA-455-200 ✓ Most Recent [ Active ]

Introduction

Intent

This Standard specifies a procedure for the measurement of the insertion loss of a fiber optic interconnection on single mode, highly linearly birefringent optical fiber, i.e. either polarization-maintaining fiber (PMF) or polarizing fiber (PZF). The connector can be mounted on the PMF/PZF pigtail of a component or part of a cable assembly. Insertion loss, as used in this Standard, is the measured attenuation of the interconnection, expressed in decibels. The method described in this Standard is the PMF/PZF equivalent of ANSI/TIA/EIA-455-171 Method D with the insertion loss reported as a positive number.

Definitions

For the purposes of this Standard, the following definitions apply.

Birefringence.

The property of a material in which orthogonal light polarizations have different indices of refraction, which cause the light at those polarizations to travel at different speeds (also referred to as the fast and slow axes). Linearly birefringent fiber maintains linear polarization states along the length of the fiber. Unstable birefringence in standard single-mode fiber causes the states of polarization to behave in an unpredictable way. Polarization-maintaining fibers are a special class of single-mode fibers with a highly birefringent waveguide structure that maintain the polarization states across the length of the fiber.

Polarizer/Analyzer.

An optical element designed to transmit light of a single polarization state -- most commonly, a linear state. When a polarizer is placed at the output of an optical system, it is called an analyzer.

Extinction.

The ratio of the optical power passed in the transmitted polarization state to the power passed in the orthogonal polarization state. The extinction of a polarizing element is measured with unpolarized light incident.

Polarization Crosstalk.

The ratio of the power that crosses over to the initially unexcited polarization state to the power that remains in the initially excited state (both powers measured at the element’s distal end). The polarization crosstalk of a birefringent element is measured with polarized light, aligned to be parallel to either of the element’s principal axes, incident.

Polarization-Maintaining Fiber (PMF).

A class of highly linearly birefringent single-mode fiber, unlike the common variety of low birefringence, single-mode fiber used in telecommunication networks. PMF is used to guide linearly polarized light from point to point, that is, to ensure that polarization does not change with distance. the birefringence of commercial PMF is stress-induced by placing the core between or within glass elements of different physical composition, or by forming a non-round core.

Polarizing Fiber (PZF).

A highly birefringent optical fiber in which only one polarization state is propagated with low attenuation.

Principal Optical Axes.

Those optical axes for which the speed of light in a linearly birefringent material is a maximum or a minimum.

Slow Axis. The optical axis of a PMF or PZF which is aligned to the stress rods (as in PANDA or Bow-tie fiber), the stress region (as in Oval stress region fiber), or the major axis of an elliptical core fiber. For PMF to be actually polarization maintaining, linearly polarized light must be aligned with one of the axes, commonly the slow axis. By convention, the anti-rotation key of the connector should be aligned with the slow axis as defined in FOCIS-4A and to be followed for other connector types.

Device Under Test (DUT).

The specimen, or device, under test.

Laser Diode (LD).

Optical power source incorporating a typically coherent laser diode as its basic emitting device.

Light-Emitting Diode (LED).

Optical power source incorporating a noncoherent light-emitting diode as its basic emitting device.