AQ6370 Optical Spectrum Analyzer (DISCONTINUED)

Notice: This product was discontinued on 10.03.31. See this replacement product:

The AQ6370 is Yokogawa's high speed and high performance Optical Spectrum Analyzer for characterization of optical communications system and optical components. Thirteen built-in optical viewer analysis functions and seven trace calculations for popular applications can be utilized with a simple function key. Yokogawa continues to provide you quality products that simplify your business practices.

AQ6370 Optical Viewer Benefits

Yokogawa's AQ6370 performs with the flexibility and simplicity you desire in an Optical Spectrum Analyzer.

World Class Optical Performance & Flexibility*
High wavelength resolution: 0.02 nm
Wide close-in dynamic range
Single Mode and Multimode fiber test capability, via the same optical input:up to GI 62.5/125nm.
Pulsed light measurement capability

Improves Measurement Throughput
Fast measurement
Fast data transfer and storage

Expedites Development of Automated Test Systems
Supports GP-IB, RS-232C, and Ethernet interfaces
Compatible with SCPI and supports AQ6317 series remote commands
Built-in simple macro programming function

 Enhances User Friendliness
Supports mouse and keyboard operation (USB & PS/2)
Trace zoom capability

Facilitates Frequent Data Handling
Large internal user memory (5000+ traces)
 Supports USB 1.1 compatible large external storage devices

Includes Wavelength Calibration Source*
In the diffraction-grating-based optical spectrum analyzer industry as of January 2006



J006 Tm Aq6370 02New High Sensitivity ModeThrough newly developed noise reduction techniques, the AQ6370 can complete a measurement faster even with a high sensitivity setting. This is imperative when measuring weak signals. A new sensitivity mode make sit up to five times faster*.



J006 Tm Aq6370 03 Seamless Sweep
With an improved gain control system in the electrical amplifier circuit, sweep speed has been increased for the signals which require multiple amplifier gain settings to complete an entire trace. The new system achieves up to ten times faster sweep*.

J006 Tm Aq6370 04Quick Key ResponseApplying a faster microprocessor and new algorithms, key response time and initial hardware setup time before a sweep is drastically reduced. The new system achieves 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 06GP-IBprovides up to ten times faster data transfer speed than the conventional GP-IB*.

J006 Tm Aq6370 06USBprovides up to ten times faster data recording/retrieving speed to a removable memory device than the floppy disk*.



J006 Tm Aq6370 07With the increased number of data sampling points (max 50,001), the AQ6370 can measure a wider wavelength range (span) with higher resolution. Single sweep can complete the test that took three sweeps in the past*.



* In comparison with AQ6317 series optical spectrum analyzer.



Expedites Development of Automated Test Systems

The AQ6370 is equipped with two 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.


SCPI is an ASCII text based standard code and format that conforms to IEEE-488.2. The standard remote commands of the AQ6370 are compatible with SCPI. It can be used with most computer test languages and test application software.


The ANDO AQ6317 series is Yokogawa’s best-selling optical spectrum analyzer. Since there are so many existing users all over the world, the AQ6370 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 the 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 AQ6370.
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 AQ6370 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.

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Front Panel Keys

Parameter entry window
appears on the screen with the entry keys for
mouse operation when a parameter is selected.


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You can easily operate the AQ6370 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.

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The functions of panel keys appear by clicking right mouse button. The functions of panel keys appear by clicking right mouse button.

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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.



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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 AQ6370 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 previewmakes it easy to find a particular file out of thousands of files. (The Thumbnail file preview function also works with an external memory.)






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The AQ6370 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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World Class Optical Performance and Flexibility*

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


The AQ6370 uses a double-pass monochromator structure to achieve high wavelength resolution (0.02 nm) and wide close-in dynamic range (70 dB). Thus, closely allocated signals and noise can be separately measured. 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
70dB at peak ± 0.4nm, resolution setting 0.02nm (typical)



Power: +20 dBm to -90 dBm
The AQ6370 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 AQ6370 covers not only telecommunication wavelengths, but also the visible light wavelength region which is used for home electronics, medical, and industrial material applications.



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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;

Modes used to obtain a better dynamic range by reducing an influence of stray-light. They are applicable in MID and HIGH mode.




The AQ6370 uses a free space input structure that can handle up to GI 62.5/125 multimode fiber on the same interface that supports single mode 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 AQ6370 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

Optional Application Software

AQ6370Viewer is PC application software designed to work with Yokogawa's AQ6370 Optical Spectrum Analyzer. It has exactly the same user interface and functions as the AQ6370 so that you can easily display and analyze waveform data acquired by the AQ6370.

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Remote control function

The remote control allows you to control AQ6370 Optical Spectrum Analyzer from anywhere on the Ethernet network. This gives you the sensation of setting measurement conditions and analysis parameters, and executing measurement on an actual unit. Because of fast data transfer speed of Ethernet, measurement data can be updated in real time. It is useful for diagnosis of trouble in production lines, periodical observation of long term tests in the lab, and other applications. Note: the data update speed varies depending on network performance and conditions.

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Image of remote access via Ethernet using the remote control function of AQ6370 Viewer

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 AQ6370. It can be edited using a spread sheet on an external computer as well.

Pas Fail Auto Test


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.




13 Auto Test


  • WDM Analysis (OSNR)
  • WDM-NF Analysis (EDFA)
  • DFB-LD Analysis
  • Filter Analysis etc.

Analysis Paramter Window


All parameters for an individual analysis are displayed in a dialog box for easy setup.


13 Auto Test 1


The AQ6370 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.

7 Trace Cal 1

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.


7 Trace Cal 2


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.

7 Trace Cal 3

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.
7 Trace Cal 4







The AQ6370 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.

Front Panel


Front Panel 2


Rear Panel

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 
Application Note

Simplified EDFA testing


To accurately measure pulsed light using an optical spectrum analyzer (OSA), it is necessary to understand the characteristics of the OSA and select the appropriate measurement method and settings.


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 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 ...


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 ...


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 ...


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 ...


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 ...


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 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.​

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



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 ...


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 ...


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.


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..


The Chopped Light mode is used: To increase measurement level sensitivity by cutting the high frequency noise To detect only the light that the LS emitted, effective for free space measurement. In free space ...

Product Overviews


    The AQ6370 Optical Spectrum Analyzer is Yokogawa's high speed and high performance Optical Spectrum Analyzer for characterization of optical communications system and optical components. Thirteen built-in analysis functions and seven trace calculations for popular applications can be utilized with a simple function key. Yokogawa continues to provide you quality products that simplify your business practices.

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