AQ6375B 2017-10-04T15:11:30+00:00

AQ6375B – Optical spectrum analyzer

High Performance LONG WAVELENGTH optical spectrum analyzer

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.

Key feature summary

  • Long wavelength range: 1200 to 2400 nm
  • Gas purging ports to reduce water vapor effects
  • Built-In cut filter for high order diffracted light
  • Double Speed Mode to further enhance fast measurement speed
  • High sensitivity down to -70 dBm
  • High resolution to 0.050 nm
  • Wide close-in dynamic range (55dB)
  • Fast auto-calibration
  • Free space optical input for maximum flexibility, low maintenance, and high reliability
  • Applicable to single-mode and multimode fibers
  • Excellent performance for environmental gas sensing Laser Spectroscopy
  • Indispensable tool for R&D and manufacturing of optical devices in the wavelength range from telecom band to 2.4µm

Items Specifications
Wavelength range *1 1200 to 2400 nm
Span *1 0.5 nm to 1200 nm (full span), and 0 nm
Wavelength accuracy *1, *2, *5 ±0.05 nm (1520 to 1580 nm), ±0.10 nm (1580 to 1620 nm), ±0.50 nm (Full range)
Wavelength repeatability *1, *2 ±0.015 nm (1 min.)
Wavelength resolution setting *1, *2 0.05, 0.1, 0.2, 0.5, 1 and 2 nm
Minimum sampling resolution *1 0.002 nm
Number of sampling 101 to 50001, AUTO
Level sensitivity setting NORM_HOLD, NORM_AUTO, NORMAL, MID, HIGH1, HIGH2 and HIGH3 (Only High dynamic mode (/CHOP) in HIGH1-3)
Level sensitivity *2, *3, *4, *6 -70 dBm (1800 to 2200 nm), -67 dBm (1500 to 1800 nm, 2200 to 2400 nm), -62 dBm (1300 to 1500 nm) (Sensitivity: HIGH3)
Maximum input power *2, *3 +20 dBm (Per channel, full wavelength range)
Maximum safe input power *2, *3 +25 dBm (Total input power)
Level accuracy *2, *3, *4, *8 ±1.0 dB (1550 nm, input level: -20 dBm, Sensitivity: MID, HIGH1-3)
Level linearity *2, *3 ±0.05 dB (Input level: -30 to +10 dBm, Sensitivity: HIGH1-3) Polarization dependence *2, *3, *8 ±0.1 dB (1550 nm)
Dynamic range *1, *2 45 dB (Peak ±0.4 nm, resolution: 0.05 nm), 55 dB (Peak ±0.8 nm, resolution: 0.05 nm)(1523 nm, Sensitivity: HIGH1-3)
Applicable fiber SM, GI (50/125 µm, 62.5/125 µm)
Optical connector Optical input : AQ9447 ( ) Connector adapter (option) required. Calibration output: AQ9441 ( ) Universal adapter (option) required. ( ) Connector type FC or SC
Built-in calibration light source Wavelength reference source (for optical alignment and wavelength calibration)
Sweep time *1, *6, *7 NORM_AUTO: 0.5 sec, NORMAL: 1 sec, MID: 10 sec, HIGH1: 20 sec
Warm-up time Minimum 1 hour (After warming up, optical alignment adjustment with built-in light source is required.)

*1: Horizontal scale: Wavelength display mode.
*2: With 9.5/125 µm single mode fiber, after 2 hours of warm-up, after optical alignment with built-in
reference light source, when the purge gas is not used.
*3: Vertical scale: Absolute power display mode, Resolution setting: ≥ 0.1 nm.
*4: With 9.5/125 µm single mode fiber (B1.1 type defined on IEC60793-2, PC polished, mode field
diameter: 9.5 µm, NA: 0.104 to 0.107).
*5: After wavelength calibration with built-in reference light source, Sampling resolution: ≤ 0.003 nm,
Sensitivity: MID, HIGH1-3
*6: Pulse light measurement mode: OFF.
*7: Span: ≤ 100 nm, Number of sampling: 1001, Average number: 1.
*8: Temperature condition changes to 23 ±3°C at 0.1 nm resolution setting.

Purge feature

Due to the high resolution and sensitivity of the AQ6375B, it can actually detect the presence of water molecules in the air. The water vapor is detected in the upper Near-IR wavelength region and could overlap with or mask the spectral characteristics of the actual device under test in that particular region.

By continuously supplying a pure purge gas such as nitrogen to the monochromator through the ports on the back panel, the AQ6375B can reduce the influence of water vapor absorptions and provide more reliable and accurate measurements than ever before.

Built-in cut filter for high order diffracted light

Due to the diffractive technology used, the monochromator in some circumstances could generate high order diffracted light, which appears at wavelengths equal to the integral multiple of input wavelengths.

By cutting incoming light below 1150 nm with the built-in filter, the AQ6375B drastically reduces the influence of high order diffracted light on the measurement. Thus, the measured data are always reliable and replicate the real signal under test.

Double speed mode

Increases the sweep speed up to 2 times compared to the standard sweep mode, with only a 2 dB penalty to the standard sensitivity value.

Long Wavelength Range: from 1200nm to 2400nm

AQ6375B-acq-dynx320The AQ6375B covers not only the wavelength span used in communications, but also the 2µm region which is used for environmental sensing, medical, biology and industrial applications.

High Sensitivity: down to -70dBm

The AQ6375B can measure optical power from +20dBm down to -70dBm thanks to its high-dynamic and very low noise components and circuits used for photo detection. This enables precise measurements of both high power and low power sources.

Measurement sensitivity can be chosen among 7 values according to the measurement speed required by the specific test to be performed.

The picture to the right shows the spectrum of a white light source (yellow) and the background noise of AQ6375B (purple).

High Resolution & Wide Dynamic Range

The AQ6375B uses a double-pass monochromator structure to achieve high wavelength resolution (0.05 nm) and wide close-in dynamic range (55 dB). Thus, closely allocated signals and noise can be separately measured.

The picture to the right shows the measured HeNe Laser (1523 nm), Close-in Dynamic range: @ peak±0.8 nm

High speed Measurement


With a proprietary sweep technique the AQ6375B achieves a much faster sweep speed than conventional measurement systems, which use a monochromator. Max. sweep time is only 0.5 sec. for 100 nm span.

Fast command processing and data transfer

Applying a fast microprocessor, the AQ6375B achieves very fast command processing speed and Ethernet interface provides up to 100 times faster data transfer speed than GP-IB.

Fast auto-calibration

The AQ6375B has a built-in reference light source for wavelength calibration and optical alignment of the monochromator components, allowing it to deliver always-accurate measurements. The calibration and alignment process takes less on the unit take than 2 minutes and is fully automatic.

NOTE: The wavelength calibration can also be performed by using an external reference source.

Free-Space Optical Input

AQ6375B-connectorx120The AQ6375B uses a free-space optical input structure, i.e. no fiber is mounted inside the instrument.

This smart solution is:
•WORRY-FREE, as no internal fiber can be scratched or get dirty
•MAINTENANCE-FREE, as no internal fiber has to be cleaned
•VERSATILE, as the instrument accepts both /PC and /APC connectors
•DUAL PURPOSE, as the instrument accepts both Single-Mode and Multi-Mode fibers without being affected by the high insertion loss from MM-SM fibers matching

A complete suite of connection interfaces

For the first time, the AQ6375B is now equipped with Gas Purging Input and Output ports for the first time along with a suite of electrical interfaces (GP-IB, RS-232, USB, RJ-45 Ethernet, SVGA video output, analog (voltage) output, trigger input & output) which allow the user to easily operate it locally in the lab as well as remotely.

Front View

Optical interfacesAQ6375B-connectorsx150

The AQ6375B adopts a universal type optical connector system for optical input and calibration output enabling direct coupling to major optical connectors (FC, SC or ST). The connectors can be replaced by users.

USB interfaces

2 ports are available on the front panel, supporting keyboard, mouse, memory stick and external HDD.

Note: USB ports can’t be used for instrument’s remote control. For this purpose the instrument has an Ethernet RJ45 port on its back panel.

Rear View



See the AQ6375B brochyre for more information.

Model Suffix Description
AQ6375B Optical Spectrum Analyzer
Spec code -10 Standard model
Built-in light source -L1 Wavelength reference source
Factory installed options
/FC AQ9447(FC) Connector Adapter For Optical Input
/SC AQ9447(SC) Connector Adapter For Optical Input
/RFC AQ9441(FC) Universal Adapter For Calibration Output
/RSC AQ9441(SC) Universal Adapter For Calibration Output

Optional Accessories:

Model Suffix Description
735371 AQ6370 Viewer (For all the AQ6370 series models)
810804602 AQ9447 Connector Adapter
Connector type -FCC FC type
Connector type -SCC SC type
813917321 AQ9441 Universal Adapter
Connector type -FCC FC type
Connector type -SCC SC type
735383 -A001 NA Conversion Adapter (for GI50/125 μm)
-A002 NA Conversion Adapter (for GI62.5/125 μm)
751535 -E5 19 inch Rack mount kit

AQ6375 Optical Spectrum Analyzer   3:08 min   Note: this video is for the AQ6375, the latest model is the AQ6375B


Testing for CO2 Gas using the AQ6375 OSA   3:21 min


Webinar – Introduction to Optical Spectrum Analyzers   51:36 min


Optical Spectrum Analyzer Applications   2:05 min


AQ6375B User Manual

For more information, see Yokogawa product page.