Space Satellite-Based Optical Amplification Measurements


Lack of reliable high-speed internet access in rural regions, due to complicated logistics and the considerable costs involved to extend land-based networks to these areas, has inspired a wave of next-generation applications that will provide greater accessibility and reliability. Making use of “space laser” networks, these revolutionary solutions can relay digital traffic via low Earth orbit (LEO) satellite systems to provide low-latency, high-speed broadband services to communities typically beyond the reach of standard wireless and fiber networks.

Used in traditional optical transmission networks, the amplification technique of employing erbium-doped fiber amplifiers (EDFA) to directly amplify optical signals (without conversion to electrical signals) has now expanded to help boost laser-based signals for orbiting satellite communication networks.

Optical amplifier measurements

Optical amplifiers are primarily evaluated with gain and noise figures (NF) via an optical spectrum analyzer (OSA) to measure the optical spectra of input, using Trace A and Trace B respectively. For select applications, a polarization scrambler is placed before the OSA to reduce the effects of the OSA's polarization dependence.

Configuration of Optical Amplifier Measurement | Space Satellite Based Optical Amplification Measurements | Yokogawa Test&Measurement
Figure 1. Basic configuration of an optical amplifier measurement

To obtain accurate gain and NF, it is necessary to exclude the source spontaneous emission (SSE) of the light source being amplified. The gain and NF is then calculated for each channel of the input optical signal. As needed, analysis parameters such as channel detection and amplified spontaneous emission (ASE) level detection should be incorporated to hone results. This can be applied to dense wavelength division multiplexing (DWDM) systems as well.

Example EDFA-NF Analysis Results | Space Satellite-Based Optical Amplification Measurements | Yokogawa Test&Measurement
Figure 2. Example EDFA-NF analysis results

Pre-measurement steps

To accurately measure the characteristics of an optical amplifier, perform the following steps first:

Step 1: Optical Alignment and Wavelength Calibration

Connect the internal calibration light source out to the optical input port with a single-mode fiber. If an internal calibration light source is not present, calibrate using a single wavelength light source with stable output, such as a DFB-LD.

Step 2: Resolution Calibration

Calibrate the resolution bandwidth of an OSA to the equivalent noise bandwidth (required by IEC standards for optical amplifier measurement) using an external light source. Resolution calibration is recommended due to the filter response of an OSA not typically being rectangular. Because of this, the resolution bandwidth (defined as FWHM) differs slightly from the equivalent noise bandwidth. This step is especially effective when wavelength resolution is 0.05 nm or less (e.g., the difference becomes prominent). With an external light source, use a stabilized single-mode laser light source with an output power of -20 dBm or more, a level stability of 0.1 dBp-p or less, and output line width of 5 MHz or less.

Step 3: Absolute Power Calibration with an Optical Power Meter

Next, calibrate the absolute power reading of the OSA. For the measurement light source, use a single-wavelength light source with stable output, such as DFB-LD and calculate the power correction factor (PCF) using the formula PCF (dB) = P_OPM (dBm) - P_OSA (dBm), where P-OPM is the optical power value on the optical power meter and P-OSA is the spectral peak power value on the OSA.

Step 4: Optical Power Correction (Power Offset)

If optical connectors, splitters, or switches are inserted between the light source and the EDFA input or between the EDFA output and the OSA, researchers must compensate for those losses. After calibrating the absolute power using an optical power meter, double check if there is extra loss that causes errors in the absolute power reading. If additional losses in the input and output paths of EDFA are uncovered, adjust correction values based upon interpolation.

Analysis parameters

Depending upon EDFA analysis needs there are multiple parameters to consider. The most-commonly used include:

Signal power

Optical amp gain and NF are obtained after measuring the signal power via the optical amp (as the output light leaves the optical amp). Peak setting is typically employed because a continuous wave (CW) laser light source is used for the EDFA measurements.


Because amplified spontaneous emission (ASE) generated by an optical amplifier is superimposed on the output light, it is important to measure this noise component separately in optical amplifier evaluation. Optical amplifier analysis identifies the ASE component using the curve fitting and interpolation methods.

  • ASE algorithm Use the ASE power calculation algorithm with the defined range of ASE data used for interpolation.
  • Fitting algorithm Optical amplifier analysis identifies the ASE component using the curve fitting and interpolation methods. In addition, the curve fitting method and analysis conditions can be set according to the actual spectrum, so the gain and NF can be obtained accurately.
  • NF calculation Calculating NF involves equations that use the refraction index, speed of light, Planck’s constant, gain value, and ASE power. NF formulas from the IEC 61290-10-4:2007 spec are shown below.
  • Resolution bandwidth When selecting the most suitable measurement method that ensures an accurate NF value, always refer to the operations manual and/or supporting technical documents for the OSA in use.


EDFA-NF analysis compliance to IEC 61290-10-4:2007

IEC-based calculations for optical amplifier test methods using multichannel parameters (interpolated source subtraction with an OSA) utilize optical power (dBm), optical frequency (Hz), and frequency resolution (Hz) for EDFA analysis.


Automated EDFA Test

An EDFA auto-test system can easily be established in conjunction with Grid TLS, optical attenuator, and optical switches. This system does not require manual reconfiguration of optical paths and adjustments of EDFA input power, and that improves measurement throughput and avoids human error. AQ2200 series is a modular system suitable for building such a system.

Screen Shot 2016 03 28 At 10.43.25 AM
Example of automated EDFA test configuration



The general amplifier gain and NF measurement principles are well-established for traditional land-based optical networks that use fiber as the transmission medium. With the push for greater accessibility and more reliable and affordable networking services, EDFA analysis algorithms with optical amplifiers have shown to be directly applicable in free-space applications as well. The tried-and-true technologies and test methods that revolutionized long-haul optical transport networks in decades past are once again pioneering communications with cutting-edge laser-based orbiting satellite networks.

Related Industries

Related Products & Solutions

AQ2200-112 LS Module (DFB, 1/2 channels)

  • AQ2200-112 Light source module
  • High output level stability performance
  • AQ2200 Multi-Application Test System

AQ2200-131/132 Grid TLS Module (C/L band, 1-channel / 2-channel)

High Stability reference laser light sources for DWDM channel measurements. The one or two channel modules are part of an integrated optical device testing solution for the AQ2200 series frame controller platform.

AQ2200-212 Sensor Module (800 to 1700 nm)

The AQ2200-212 is single channel sensor module with an analog output port.

AQ2200-215 Sensor module (high Power up to +30dBm, 970 to 1660 nm)

Ideal for measuring output power of transmission equipment and optical fiber amplifiers.

AQ2200-222 Dual Sensor Module (800 to 1700 nm)

Increase your testing power and capability with the AQ2200-222 sensor module.

AQ2200-232 Optical Sensor Head (Large diameter detector, 800 to 1700 nm), AQ2200-242 Optical Sensor Head (Large diameter detector, 400 to 1100 nm), AQ2200-202 Interface Module (2-channels)

  • AQ2200-232 Optical Sensor Head (Large diameter detector, 800 to 1700 nm)
  • AQ2200-242 Optical Sensor Head (Large diameter detector, 400 to 1100 nm)
  • AQ2200-202 Interface Module (2-channels)
  • High performance optical sensor heads and interface module 

AQ2200-312 Optical Attenuator module

  • AQ2200-312 Variable Optical Attenuator Module from Yokogawa Test&Measurement 
  • Small, lightweight variable optical attenuator providing low insertion loss
  • SM, GI50, and GI62.5 fiber optic attenuator types available

AQ2200-332 Optical Attenuator module

With built-in optical power meter for monitoring power
Compact and lightweight optical variable attenuator.
SM, GI50 and GI62.5 optical fiber models available.

AQ2200-411 Optical Switch Module (1 x 4/1 x 8)

  • AQ2200-411 Optical Switch Module 
  • Superior switching reproducibility
  • Compact optical switches
  • SM, GI50 and GI62.5 optical fiber models available

AQ2200-412 Optical Switch Module (1 x 16)

  • AQ2200-412 Optical Switch Module
  • Superior switching reproducibility
  • Compact
  • SM & GI50 optical fiber models available

AQ2200-421 Optical Switch Module (1 x 2/2 x 2)

  • AQ2200-421 Optical Switch Module
  • Superior switching reproducibility
  • Compact optical switches
  • SM, GI50 and GI62.5 optical fiber models available

AQ2211 Frame Controller (3 Slots)

  • AQ2211 Frame Controller
  • Multi application testing system
  • Hot-swapping capability
  • Remote monitoring and control
  • Even easier with Ethernet support

AQ2212 Frame Controller (9 Slots)

  • AQ2212 Frame Controller
  • Multi application test system
  • Two frame controller platforms
  • Select best platform size for intended measurement applications

AQ6360 Telecom Production 1200 - 1650 nm and 700 - 1700 nm

  • AQ6360 optical analyzer
  • Cost-effective optical spectrum analyzer
  • Diffraction grating technology
  • Ideal for optical device manufacturing

AQ6370D Telecom Optical Spectrum Analyzer 600 - 1700 nm

  • AQ6370D Optical Spectrum Analyzer
  • Popular TELECOM wavelength Range of 600nm to1700nm
  • Ideal model for Telecommunications applications for single-mode and multi-mode optics


AQ6373B Visible Wavelength Optical Spectrum Analyzer 350 - 1200 nm

  • Dedicated SHORT wavelength Range of 350nm to1200nm
  • Accurately measure visible spectrum of 380nm to 780nm
  • Bio-sciences and beyond
  • Measuring 1064nm Nd:YAG, DPSS Laser sources

AQ6374 Wide Range Optical Spectrum Analyzer 350 – 1750 nm

  • AQ6374 Wide Range Optical Spectrum Analyzer
  • Covers wavelengths from 350 to 1750 nm
  • Visible lights (380 to 780 nm) and telecommunication wavelengths

AQ6375B Long Wavelength Optical Spectrum Analyzer 1200 - 2400 nm

High Performance LONG WAVELENGTH
The AQ6375B is a bench-top optical spectrum analyzer covering the long wavelengths, 1200 to 2400 nm, with the added benefits of gas purging input ports / output ports, a built-in cut filter for high order diffracted light, and a novel double speed mode which increases the sweep speed up to 2 times compared to the standard sweep mode.

AQ6376 Three Micron Optical Spectrum Analyzer 1500 - 3400 nm

MWIR WAVELENGTH with internal gas purge and cut filter
The AQ6376 is the latest version of our bench-top optical spectrum analyzer extending the wavelength coverage well beyond the NIR range of our previous models into the MWIR region from 1500 to 3400 nm.
Popular applications include the detection of gases such as carbon oxides (COx), nitrogen oxides (NOx), and hydrocarbon gas (CxHy) for environmental studies.

AQ6380 Highest Performance 1200 - 1650 nm and 900 - 1650 nm

AQ6380 OSA: 5 pm (0.624 GHz) high wavelength resolution, ±5 pm accuracy, 65 dB wide close-in dynamic range, 80 dB high stray light suppression

Modular Manufacturing Test System

A modular test platform with a wide selection of modules allows optimal configuration of test solutions for optical component and network systems manufacturing.

Optical Spectrum Analyzers

Measures the power intensity of light across different wavelengths in the electromagnetic spectrum.

Optical Test Equipment

  • Yokogawa optical test equipment solutions to measure optical components/systems
  • Serves demand for high capacity fiber lines and new component technologies

Precision Making