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Fiber Optic Patch Cord Insertion Loss, Return Loss Measurement
Oct 27, 2017

0 Introduction

Fiber insertion jumper is widely used in the field of optical communication and optoelectronics. Insertion loss (insertion loss) and return loss (return loss) are two important indicators of Fiber Optic Patch Cord. The insertion loss will weaken the optical power in the optical path, System sensitivity; its return loss will change the spectral width of the laser diode, introduce noise into the system, and even change the wavelength of the light source. Accurate measurement of Fiber Optic Patch Cord insertion loss, return loss indicators to meet the requirements, is to ensure that all kinds of fiber optic equipment, a prerequisite for normal work.

China AV4 produced by the AV6332 optical return loss tester using ultra-low reflection of the optical device and in-phase detection technology, you can simultaneously accurately measure the Fiber Optic Patch Cord insertion loss and return loss for single-mode fiber optic cable, optical devices The measurement of insertion loss and return loss.

1 parameter definition

Fiber Optic Patch Cord insertion loss refers to the optical signal through the Fiber Optic Patch Cord, the output optical power relative to the input optical power decibel number. The calculation formula for the insertion loss is shown in equation (1):

IL (dB) = - 10lgPout / Pin (1)

Where Pin is the input optical power and Pout is the output optical power. Insertion loss is positive, the smaller the value the better. Fiber bridge jumper loss is the optical signal through the Fiber Optic Patch Cord connection, the backward reflected light power relative to the optical power of the decibel

number. The formula for the return loss is shown in (2)

RL (dB) = -10lg Pr Pin (2)

Where Pin is the input optical power and Pr is the retroreflective optical power. Return loss is positive, the greater the value the better.

2 measurement principle

A complete return loss test system consists of the AV6332 optical return loss tester and a single mode modulated light source (eg AV38121A, AV38124A, AV38126A). AV6332 optical return loss tester and single-mode modulation light source to be connected with BNC cable to achieve in-phase detection.

AV6332 measurement Fiber Optic Patch Cord insertion loss principle is to use the instrument comes with optical power meter to measure the optical power of the reference fiber output, and the optical power meter is set to the relative measurement mode (that is, the instrument panel display 0.00dB), and then the measured fiber The jumper is connected to the reference fiber, and the output optical power of the measured fiber is measured by the above optical power meter. The display value of the instrument panel is the insertion loss of the measured Fiber Optic Patch Cord.

AV6332 measurement Fiber Optic Patch Cord return loss principle is the use of light from the reference fiber perpendicular to the air Fresnel reflection of the return loss of 14.8dB (ie, the reflection coefficient of 3.5%) as the instrument's return loss reference calibration value, and then Deduct the residual light reflection of the instrument itself, you can accurately measure the measured Fiber Optic Patch Cord (connector pair) return loss.