Measuring IL & RL

AN-147 Mechanical Shock Testing for Insertion Loss and Return Loss of Optical Connectors and Components

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by Kate Torrence
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AN-147 Mechanical Shock Testing for Insertion Loss and Return Loss of Optical Connectors and Components

Overview

 Shock monitoring allows us to evaluate the performance and connectivity of a mated pair of optical connectors through shock events. Many solutions require an optical power meter with an analog output (optical-to-electrical converter) and a sampling device, such as an oscilloscope, to digitally capture and analyze the transient signal. Such solutions require calibration practices to ensure the sampling device and analog signal accurately represent the optical signal levels. The OP740 and supporting software combines this functionality into an all-in-one solution with no need for an external capturing device or excessive focus on calibration.

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AN-146 Analyzing Dynamic Fiber Optic Components Using the OP740: Optical Switches

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by Kate Torrence
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AN-146 Analyzing Dynamic Fiber Optic Components Using the OP740: Optical Switches

Overview

 The OP740 can be used to capture dynamic optical signals. In this example, the OP740 will be used to monitor the switching behavior of two types of optical switches: Mechanical and MEMs based.

AN-146 Figure 1 OP715 + OP720 + OP740 illustration

Figure 1: High-speed multichannel Optical Power Meter and two optical switches.

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AN-145 Measuring ILRL and Verifying Polarity

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by Kate Torrence
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  AN-145 Measuring Insertion Loss and Return Loss and Verifying Polarity

Overview

Polarity testing and Insertion Loss (IL) testing are crucial steps in the production and assessment of multi-stranded fiber optic cables. With certain setups, IL can be measured while verifying polarity.

The IL test measures the amount of light lost when traveling through the DUT en route to the detector. A test setup that uses a multichannel source and multichannel power meter evaluates the light paths of a multifiber device under test (DUT) one at a time. If any of the fibers are crossed or broken, light does not reach the OPM on the expected channel resulting in dark values. Using an Insertion Loss and Return Loss (RL) meter as the source instrument and a multichannel power meter as the detector allows for 3-in-1 IL, RL, and polarity evaluation.

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AN-143 Insertion Loss and Return Loss Testing of Short Cables and Assemblies (including TOSA and cassettes)

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by Alex Test
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AN-143 Insertion Loss and Return Loss Testing of Short Cables and Assemblies (including TOSA and cassettes)

Overview

As fiber optic infrastructure and components are designed more densely and more compactly, patch cords, cassettes, and optical subassembly cables have followed suit by becoming shorter and shorter. These short cables, which can sometimes be just 20cm in length, present certain problems for testing return loss (RL). Most RL meters, whether pulse-based or Optical Continuous Wave Reflectometer (OCWR) based, have difficulty accurately measuring the return loss of these cables. Often, the return loss from the back connector of the device under test interferes with the measurement of the front connector.

MTP saver cable
Figure 1: Short MTP®/MPO - MTP®/MPO cable
AN143 Cassette
Figure 2: LC breakout cassette
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AN-117 Measuring Insertion Loss and Return Loss of Hybrid Cables in OPL-MAX

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by Kate Torrence
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AN-117 Measuring Insertion Loss and Return Loss of Hybrid Cables in OPL-MAX

Overview

Obtaining connector-level insertion loss (IL) and return loss (RL) for hybrid cables is complicated by the different connector types on either end of the cable. Hybrid cables cannot simply be flipped to test the reverse direction when the reference and device under test (DUT) connectors are no longer compatible. A test setup comprised of the OP940 IL and RL Meter with two detectors, the OP725 Benchtop Optical Switch, and OPL-Max Application Software solves the compatibility issue and allows for hybrid cable testing with high speed, accuracy, and repeatability.

*Details on how to perform these measurements through the front panel of the OP940 can be found in Application Note AN-111 Measuring Insertion Loss and Return Loss on Hybrid Cables.

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AN-116 Performing ILRL Measurements Using a Single-Channel OP940

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by Alex Test
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AN-116 Performing Insertion Loss and Return Loss Measurements Using a Single-Channel OP940

Overview

OptoTest’s OP940 allows operators to test Insertion Loss and Return Loss of fiber optic cables accurately and efficiently. Once Insertion Loss and Return Loss references are completed, the unit will automatically update test results on the screen in real-time.

Performing a Reference Measurement

Return Loss Reference

The OP940 references Return Loss by searching for the first large reflection in the reference cable. After such a reflection is found, measurements begin at a distance from the front panel to the unmated end of the cable. It is recommended that an unmated PC connector be used for RL reference (for more information see our White Paper) and that the number of connections between the front panel and the reference connector be minimized to reduce loss and reflectors to the OP940 front panel. The open PC connector should yield approximately 14dB reflection.

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AN-111 Measuring Insertion Loss and Return Loss on Hybrid Cables

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by Alex Test
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AN-111 Measuring IL/RL on Hybrid Cables

Overview

Testing simplex cables with unmatched connector types poses difficulties because the cable cannot simply be turned around to test the reverse direction. While hybrid bulkheads (SC-FC, ST-FC, etc.) are one option that can solve the problem with only minor issues, in some circumstances hybrid bulkheads will not provide sufficiently accurate measurements. SC-LC cables are one such example. SC-LC bulkheads have high loss and poor repeatability and, as a result, they should not be used in the testing process. Using an OP940 with two detector ports coupled with an OP725 will allow the operator to accurately test hybrid cables of all configurations with the highest accuracy possible.

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AN-128 Ensuring Accurate Return Loss Measurement

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by Alex Test
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AN-128 Ensuring Accurate Return Loss Measurement

Overview

As fiber optic networks move towards higher data rates and lower loss, connectors with increased performance (low insertion and return loss) have become the standard.  Return loss requirements on connectors have begun to approach the physical limitations of the polishing process and, as such, any error in the measurement can cause poor connectors to pass or good connectors to fail.

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AN-112 Testing Insertion Loss and Return Loss on Ribbon Fiber Fanouts with OPL-MAX

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by Alex Test
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AN-112 Testing Insertion Loss and Return Loss on Ribbon Fiber Fanouts with OPL-MAX

Overview

Measuring Insertion Loss and Return Loss on Ribbon Fiber Fanouts, like the MTP® to LC cable shown in figure 1 below, can be a streamlined process when using the right equipment and automation software.

For the methods described in this Application Note, only a multichannel IL/RL Tester (OP940) fitted with large area detector (RIN) or integrating sphere (OP-SPHR) is needed. This setup can greatly reduce testing time and inaccuracies caused by additional reference cables and multiple detectors. For even further efficiency in testing, using OPL-MAX software will automate and store all test results.

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AN-140 RL Testing for APC Terminated Cables using the OP940 Front Panel

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by Alex Test
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AN-140 SRL Testing for APC Terminated Cables using the OP940 Front Panel

Overview

The OP940 was designed as an upgrade to the existing OP930 product line. One of the many additional features is the ability to reference to an angle polished connector through the front panel of the unit. The new feature works by searching for small reflections that the unit would normally bypass. If, after following the instructions below, the unit is unable to reference to the APC connector on the reference cable, it is advised to employ the methods detailed in AN-114 RL Testing for APC Terminated Cables.

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