AQ6370B Optical Spectrum Analyzer (DISCONTINUED)

Notice: This product was discontinued on 10.12.15. See this replacement product:

Redefining Optical Spectrum Measurement Excellence!

Drastically Improves Measurement Throughput

  • Fast measurement
  • Enhanced User Interface
  • World Class Optical Performance¹
    • High wavelength resolution: 0.02 nm
  • Multimode Fiber test capability
  • DWDM 25Ghz Channel Spacing Test supported

: In the diffraction-grating-based optical spectrum analyzer industry as of July 2008

World Class Optical Performance and Flexibility*

          * In the diffraction-grating-based optical spectrum analyzer industries as of January 2006


The AQ6370B uses a newly developed high performance monochromator to achieve high wavelength resolution (0.02 nm) and wide close-in dynamic range (70 dB).
With the sharper spectral characteristics of the new monochromator, OSNR measurement of 50 GHz spacing DWDM transmission systems and EDFA evaluation with multiple wavelength sources can successfully be performed.

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Close-in Dynamic Range
70 dB at peak ±0.4 nm, resolution setting 0.02 nm (typical)


Power: +20 dBm to -90 dBm
The AQ6370B can measure optical power as high as +20 dBm, which enables direct measurement of high power sources such as optical amplifiers and pump lasers for Raman amplifiers. Measurement sensitivity can be chosen from seven categories according to test applications and measurement speed requirements.
Wavelength: 600 nm to 1700 nm
The AQ6370B covers not only telecommunication wavelengths, but also the visible light wavelength region which is used for home electronics, medical, and industrial material applications.
J009 Tm Aq6370 22J009 Tm Aq6370 23 Level sensitivity settings
NORM Hold, NORM Auto, NORM, MID, and HIGH (1, 2, and 3), that correspond to sensitivity from -60dBm through -90dBm.

High dynamic range mode settings
SWITCH mode is to obtain a better dynamic range by reducing an influence of stray-light. They are applicable in MID and HIGH mode.


The AQ6370B uses a free space input structure that can handle up to GI 62.5/125 multimode fiber. Multimode fiber is commonly used in high speed Ethernet network, such as GE-PON.
The free space input is also beneficial for measurement repeatability as insertion loss variation at the input connector is smaller than the other input type which has an optical fiber inside the monochromator.
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Sample waveform of an 850nm laser
with a multimode fiber (62.5/125mm)
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Structure of the free space
monochromator input


The AQ6370B can catch the peak power of a pulsed signal using PEAK HOLD or using an externally provided trigger to synchronize with the measured signal. It can be applied to the transmission loop testing of telecommunication systems, and also to the low power measurement at the early stage of laser chip development since it works in the high sensitivity modes.            
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Sample waveform of a pulsed light signal

Real-Time Remote Operation for Monitoring and Troubleshooting

AQ6370B Viewer (Optional Application Software)
The AQ6370Viewer is a package of the PC application softwares for AQ6370, AQ6370B, and AQ6375.
The AQ6370BViewer is designed to work with the AQ6370B Optical Spectrum Analyzer. It has the same user interface and functions as the AQ6370B so that you can easily display and analyze waveform data acquired by the AQ6370B.

Viewer Function
Trace data files saved on the AQ6370B can be retrieved and analyzed on a PC.
Note. Measurement cannot be initiated in the Viewer mode.

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Screen example of AQ6370B Viewer

Remote Control function 
The remote control allows you to set measurement conditions and to execute a measurement on AQ6370B Optical Spectrum Analyzer from anywhere on the Ethernet network. Upon completion of a measurement on AQ6370B, AQ6370B Viewer downloads and shows the updated traces.

Note. The program function is not supported. Some other restrictions may apply.



File Transfer Function
Files can be exchanged between AQ6370B and PC. Program files edited on AQ6370B Viewer can also be transferred to AQ6370B.
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PC Requirements 




  • HDD: 50 MB or more of available disk space
  • Memory: 512 MB or more




  • Windows 2000 (Service Pack 4 or later) or
  • Windows XP (Service Pack 1 or later)

*Windows 2000 and Windows XP are registered trademarks of Microsoft Corporation of the United States.





Fast Measurement
J006 Tm Aq6370 03Through newly developed monochromator, the fast electrical circuit, and the noise reduction techniques, the AQ6370B can complete a measurement faster even when measuring a steep spectrum from DFB -LD or DWDM signals, or when measuring a low power signal from a broadband light source. *
Key & Command Response
J006 Tm Aq6370 04Applying a faster microprocessor and new algorithms, key response time and command processing time is drastically reduced. AQ6370B can achieve up to one hundred times faster response*.





J006 Tm Aq6370 05ETHERNET provides up to one hundred times faster data transfer speed than the GP-IB data transfer*.  
J006 Tm Aq6370 06USB provides up to ten times faster data recording/retrieving speed to a removable memory device than the floppy disk*.
J006 Tm Aq6370 06GP-IB provides up to ten times faster data transfer speed than the conventional GP-IB*.  

*In comparison with AQ6317 series optical spectrum analyzer.



Expedites Development of Automated Test Systems


The AQ6370B is equipped with GP-IB, RS-232C, and Ethernet (10/100BASE) interfaces to be connected with an external PC for remote access and building an automated test system. It is compatible with a standardized programming language and supports AQ6317 commands for easy programming. Macro Program is a useful built-in function for making a simple auto test program.



The SCPI is an ASCII text based standard code and format that conforms to IEEE-488.2. The standard remote commands of the AQ6370B are compatible with SCPI. It can be used with most computer test languages and test application software.

The AQ6317 series is Yokogawa's best-selling optical spectrum analyzer. Since there are so many existing users all over the world, the AQ6370B supports private remote programming codes and formats of the AQ6317 series to make it easier for users to upgrade their current test environment.

Note. some commands may not be compatible due to changes in specifications and functions.
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Image of OSA upgrading on the existing test system



Macro programming enables user to easily create test procedures by recording the user's actual key strokes and parameter selections. One program can contain up to two hundred program lines, and programs can be called as subroutines to make the main program simple. Moreover, macro programs can control external equipment through Ethernet, RS-232C and GP-IB port (GP-IB2). Therefore, an external PC is not required to build a simple auto test system.

LabVIEW® is a popular test application software. Yokogawa can provide users with LabVIEW drivers for the AQ6370B.

Note. LabVIEW is a U.S. registered trademark of National Instruments.

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Example of a simple auto test system with Macro program

Enhances User Friendliness


The AQ6370B inherits front panel operation and function key assignments from our conventional models that are proven intuitive and easy to use by our multitude of users.

J008 Tm Aq6370 11Parameter entry window
appears on the screen with the entry keys for
mouse operation when a parameter is selected.
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Front panel keys

You can easily operate the AQ6370B with only a mouse instead of the front panel keys. Measuring conditions displayed on the trace screen can be changed directly by the mouse pointer. The keyboard is useful for entering labels and file names.
J008 Tm Aq6370 12The functions of panel keys appear by clicking right mouse button. J008 Tm Aq6370 13
Direct parameter entry
Arrow pointer transforms into finger pointer when you move it to parameters.

Trace zoom makes it possible to change display conditions, such as center wavelength and span, by clicking and dragging the mouse to select the designated area to enlarge. No need to make another sweep to refresh the display conditions anymore. The analysis function can be performed in the enlarged area.
J008 Tm Aq6370 14 Overview Window
Once the trace is zoomed in, the overview window appears and shows the entire trace. By dragging the zoomed area border in this window with the mouse, the display area in the main trace window can be modified.
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In the Analysis Screen, traces can also be zoomed. When a line item on the analysis result table is selected, the display area is automatically shifted and the corresponding signal is centered in the display area. This makes it easier to verify the accuracy of the analyzed data.

Facilitates Frequent Data Handling



J008 Tm Aq6370 17The AQ6370B has a 128 MB user area in the internal memory that can save test setups, waveforms, analysis results, and macro program files. It is large enough to save more than five thousand traces.
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Thumbnail file preview makes it easy to find a particular file out of thousands of files. (The Thumbnail file preview function also works with an external memory.)
J008 Tm Aq6370 19The AQ6370B has two USB 1.1 compatible interfaces. They support large size removable memory devices such as Flash ROM and hard disk drives (HDD). Removable static memory of more than 1 GB and USB compatible external HDDs of more than 40 GB in capacity are commercially available. (as of January 2006)
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Advantageous Functions


The waveform can automatically be judged to PASS or FAIL against specified conditions. Using Template function upper and/or lower limits for the assessment can be set and measured waveform can automatically be compared. It is an effective way to reduce time and human error in assessment, especially for production line tests.
The template data can be created and stored in the AQ6370B. It can be edited using a spread sheet on an external computer as well.

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Thirteen types of built-in analysis functions for popular applications can be selected by using Analysis function key on front panel or by mouse operation.
The functions automatically perform designated analyses and provide results. The results can be saved in a storage device.
  • WDM analysis (OSNR)
  • WDM-NF analysis (EDFA)
  • DFB-LD analysis
  • Filter analysis, etc.
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Tm Aq6370 31 Analysis Parameter Window
All parameters for an individual analysis are displayed in a dialog box for easy setup.


The AQ6370B has seven individual traces for measurement data. Some traces can be used for calculations (two-trace subtraction and addition), MAX/MIN hold, averaging, and curve fitting.



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Enhanced Curve Fit Function
The Curve fit function is an approximation technique to exclude an influence of noise and/or signal overlapping on the waveform. Curve fit method can be chosen from Gaussian, Lorenz, 3rd Poly, 4th Poly, and 5th Poly. Curve fit can be applied to an individual trace. Fitting area can be set by line markers (L1 and L2).
Analysis mode
When WDM or WDM-NF analysis is executed, one of the curve fit methods is used for a baseline measurement. The curve fit method can be specified in the parameter window of each analysis.
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Example of curve fitting in selected areas
Noise level of amplified WDM signal can be estimated by using the curve fit in selected areas, even if noise between signals cannot be seen due to a limit of signal separation performance.
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Marker fitting
The fitting curve can also be applied to the marker positions set by user. For example, this can be used to measure a modulated signal spectrum.
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Front Panel
The AQ6370B adopts a universal type optical connector system for optical input and calibration output enabling direct coupling to major optical connector types.
The connectors can be replaced by users.
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NA Conversion Adapter

  • 735383-A001, A002 numerical aperture conversion adapters
  • Half numerical aperture of optical fiber 
  • AQ6370 series optical spectrum analyzers' free-space optical input structure 

If you have products currently in China that require calibration or repair, you may either return them to your local Yokogawa service center or the Yokogawa China Service & Repair Center.   Please be advised that ...


The AQ637X Optical Spectrum Analyzer has a feature called Auto Offset that it performs every 10 minutes. What this feature does is zero out the OP amps in the OSA to ensure constant level accuracy. This feature will however, stop the OSA ...


For the AQ6373 Optical Spectrum Analyzer you can use a maximum 800 micron core fiber that must be terminated in a standard FC connector.   For the AQ6375 and AQ6370 series OSA you can use a maximum 200 micron core fiber which, ...

  • It is possible to convert an AQ6370 Optical Spectrum Analyzer Binary file to ASCII .CSV file using the AQ6370 Viewer Software? 
  • Different AQ637X series OSA Viewer software will load specific binary file extensions.

The AQ6370C Optical Spectrum Analyzer was developed in accordance with the IEC standard: WG4 (IEC 61280-1-3) Test procedures for general communication subsystems -Central wavelength and spectral width measurement. We cannot guarantee the RMS ...


The remote viewer may not start if the screen resolution is too low.  Adjust the screen resolution to 1024 by 768 pixels (or larger) then restart the software.​


Yes, the AQ6370 Optical Spectrum Analyzer Viewer Software is compatible with Windows 7 32-bit and 64-bit. Note: Please make sure the correct USB driver is installed for either Windows 7 32-bit or 64-bit.


Level Accuracy:Level Accuracy is a tolerance to the true value of measured value, when a standard level is measured with a standard wavelength. Level Linearity:Level Linearity is the width of error dispersion ...


No, unfortunately due to the number of current fiber combinations, we do not stock optical fibers. There are many companies that specialize in optical fiber cords.


The resolution is controlled by 3 factors: Input Slit Detraction Grating  Output Slit The resolution setting controls the output slit disk. This disk has a fixed number of slits in it. Since the setting only control ...


The maximum input power that the AQ6370B Optical Spectrum Analyzer can measure for pulsed light measurements is +20dBm per resolution at full span, per channel. Keep in mind that this limit is applicable to an averaged power of pulsed light, ...


If the AQ637X series Optical Spectrum Analyzer is already running and you attempt to connect an external display, the OSA will not automatically detect the external display. The OSA will need to be re-booted before it can recognize and ...

  • AQ637X Optical Spectrum Analyzer sanitation procedure
  • Restore settings to defaults with parameter initialization



Please download the attached application note for instructions on how to make High Bit Rate Modulated OSNR Measurement for the AQ6319 and AQ6370 series Optical Spectrum Analyzer..


If you are performing wavelength calibration using the instrument's built-in light source, the warning message is an indication that the monochromator needs to be repaired. Please visit our Contact site to locate ...


The AQ6370 OSA cannot load and re-display the data saved by an AQ6370B. However, the AQ6370 Viewer software can display the data saved by both instruments. Also please note that the AQ6370B OSA can load and re-display ...


Wavelength accuracy: Wavelength accuracy is a tolerance to the true value of a measured value when the standard wavelength is measured.  Wavelength repeatability:Wavelength repeatability is the stability of ...

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