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Bristol Instruments 428 Series Multi-Wavelength Meter

Test your WDM signals with the confidence that results from reliable accuracy.

Bristol Instruments provides a family of optical wavelength meters and multi-wavelength meters designed specifically for the testing of WDM lasers and WDM systems. Absolute laser wavelength is measured to an accuracy as high as ± 0.3 pm. This performance is guaranteed by continuous calibration with a built-in wavelength standard and is traceable to NIST standards. Straightforward operation and rugged design satisfy the needs of both the R&D scientist and the manufacturing engineer.

Bristol Instruments 428 Series Multi-Wavelength Meter
Multi-wavelength, CW and modulated signals


In order to fully characterize WDM components and transmission systems, the 428 Series Multi-Wavelength Meter simultaneously measures wavelength, power, and OSNR of up to 1000 discrete optical signals. Wavelength is measured to an accuracy as high as ± 0.3 pm, power is measured to an accuracy of ± 0.5 dB, and OSNR is calculated to greater than 40 dB. In addition, optical spectrum analyzer software is included to generate and display a high-resolution spectrum of the optical signal under test.

  • » Simultaneously measures wavelength and power of up to 1000 optical signals
  • » Absolute wavelength measured to an accuracy as high as ± 0.3 pm
  • » Continuous calibration with a built-in wavelength standard
  • » Measurement confidence level of >99.7%
  • » Traceable to NIST standards
  • » Power measured to an accuracy of ± 0.5 dB
  • » Automatic calculation of OSNR to >40 dB
  • » Optical spectral analysis with resolution of 10 GHz
  • » Measurement time of 0.25 s
  • » Input power requirement of -40 dBm
  • » Operation with CW and modulated signals
  • » SCPI interface via USB 2.0, Ethernet, or GPIB
  • » Rugged design for manufacturing environments

Simultaneous wavelength, power, and OSNR measurement
The 428 Multi-Wavelength Meter combines proven Michelson interferometer-based technology with fast Fourier transform analysis. This results in the ability to measure the wavelength and power of up to 1000 discrete optical signals. Wavelength is measured to an accuracy as high as ± 0.3 pm and power is measured to an accuracy of ± 0.5 dB. In addition, the 428 system automatically calculates OSNR to greater than 40 dB.

Reliable accuracy with continuous calibration 
Two versions of the 428 Multi-Wavelength Meter are available. The model 428A is the most accurate, measuring wavelength to ± 0.3 pm. For less exacting test requirements, the model 428B is a lower-priced alternative with a wavelength accuracy of ± 1.0 pm. The wavelength accuracy of the 428 system is maintained over long periods of time because it is continuously calibrated with a built-in HeNe laser wavelength standard. In order to achieve the highest accuracy, the model 428A uses a single-frequency HeNe laser that is stabilized using a precise balanced longitudinal mode technique. A standard HeNe laser is used as the wavelength reference in the model 428B. The result is a measurement confidence level of 3-sigma. To verify this performance, every 428 system is rigorously tested with laser sources that are traceable to an NIST standard.

High-resolution spectral analysis 
To provide the most complete analysis of the WDM signal, special Optical Spectrum Analyzer Software is included with the 428 Multi-Wavelength Meter. This software measures the spectrum of the optical input signal to a resolution of better than 10 GHz resulting in the ability to easily discriminate between closely spaced WDM channels. The software operates on a PC running under Windows and data generated by the 428 system is transferred using a USB or Ethernet interface.

Designed for productivity and convenience
Operation of the 428 Multi-Wavelength Meter is straightforward. The optical signal enters the model 428 through an FC (UPC or APC) fiber-optic connector on the front panel. The system’s high sensitivity results in an input power requirement of only 0.1 µW (-40 dBm). Automatic electronic gain control instantly adjusts the photodetector signal for optimum performance. The controls of the 428 system are user-friendly and conveniently located on the front panel along with the measurement display. The wavelength, power, and OSNR data can be reported in a variety of formats. Data from a specific optical channel can be displayed, or lists of data from all channels, sorted by wavelength or power, can be displayed. The measurement information can also be sent to a PC using a standard USB or Ethernet interface, or an optional GPIB interface. Finally, the 428 system is packaged in a rugged chassis (bench top or rack-mounted) for use in typical laboratory or manufacturing environments.


MODEL 428A 428B
LASER TYPE CW and modulated
WAVELENGTH RANGE 1270 – 1650 nm (182 – 236 THz)
WAVELENGTH ACCURACY ± 0.3 pm  ± 1.0 pm
MINIMUM RESOLVABLE SEPARATION 10 GHz, equal power lines input
CALIBRATION Continuous with built-in
stabilized single-frequency HeNe laser
Continuous with built-in
standard HeNe laser
POWER ACCURACY ± 0.5 dB (± 30 nm from the 1310 and 1550 nm)
SIGNAL-TO-NOISE RATIO >40 dB with 100 averages, 100 GHz channel spacing
>35 dB with 100 averages, 50 GHz channel spacing
MINIMUM INPUT -40 dBm (1270 – 1600 nm, -30 dBm (1600 – 1650 nm)
MEASUREMENT MODES Single channel, list by wavelength table, list by power table
Delta wavelength from ITU grid, delta wavelength/power from reference channel
Maximum, minimum, drift (max-min) of wavelengths and powers over time
Current, start, drift (current-start) of wavelengths and powers over time
OPTICAL INPUT 9/125 μm single-mode fiber (FC/UPC or FC/APC)
INSTRUMENT INTERFACE SCPI via USB, Ethernet, and optional GPIB (LabVIEW examples provided)