Laser 2000

Multi-Wavelength Meter

Two versions of the 438 Multi-Wavelength Meter are available. The model 438A is the most precise, providing an accuracy of ± 0.3 pm. For less exacting test requirements, the 438B system is a lower-priced alternative with a wavelength accuracy of ± 1.0 pm.

Bristol Instruments

The fastest multi-wavelength measurement available

438 Series Multi-Wavelength Meter

  • Wavelength accuracy as high as ± 0.3 pm
  • Continuous calibration with a built-in wavelength standard
  • Measurement confidence level of ≥ 99.7%
  • Power measured to an accuracy of ± 0.5 dB
  • Automatically calculates OSNR to > 40 dB
  • Automatic reporting of SMSR
  • Fastest measurement rate of 10 Hz
  • Broad operational range of 1000 nm to 1680 nm
  • Operates with CW and modulated signals
  • Convenient touch-screen display reports measurement data in a variety of formats
  • Interfacing via SCPI using USB, Ethernet, or GPIB
  • Rugged design for manufacturing environments
  • Five-year warranty covers all parts and labour


The 438 Series Multi-Wavelength Meter from Bristol Instruments combines proven Michelson interferometer-based technology with fast Fourier transform analysis to measure the wavelength, power, and OSNR of as many as 1000 discrete optical signals.

With features such as high accuracy, measurement rate up to 10 Hz, and a broad operational range of 1000 to 1680 nm, the model 438 provides the most precise, efficient, and versatile wavelength testing of optical transceivers and WDM signals.

Reliable accuracy with continuous calibration
Continuous calibration with a built-in wavelength standard maintains the performance of the 438 Multi-Wavelength Meter over long periods of time. What’s more, every 438 system is rigorously tested with laser sources that are traceable to NIST standards.

Designed for convenience, built to last
Operation of the 438 Multi-Wavelength Meter is straightforward.

The optical signal enters the model 438 through an FC (UPC or APC) fibre optic connector on the front panel. The system’s high sensitivity results in an input power requirement as low as -40 dBm (0.1 µW). Automatic attenuation instantly adjusts the signal for optimum performance.

A convenient touch-screen display on the instrument’s front panel controls the 438 system and reports the measured wavelength, power and OSNR. Data from a specific optical channel can be displayed, or lists of data from all channels, sorted by wavelength or power, can be reported. The measurement information can also be sent to a PC using a library of SCPI commands via standard USB or Ethernet interface, or an optional GPIB interface.

Optical Spectrum Analyser software is also available to generate and display the spectrum of an optical signal to a resolution better than 10 GHz (0.08 nm). This provides the ability to analyse closely-spaced WDM channels and to determine the side-mode suppression ratio of optical transceivers.

The rugged design of the 438 Multi-Wavelength Meter provides long-term reliable operation that is backed by a five-year warranty covering all parts and labour.

Model 438A 438B
Optical Signal CW and modulated
Range Option -001: 1270 – 1680 nm (179 – 236 THz)
Option -002: 1000 – 1680 nm (179 – 300 THz)
Accuracy [1], [2], [3] ± 0.2 parts per million (± 0.3 pm at 1550 nm) ± 0.65 parts per million (± 1.0 pm at 1550 nm)
Differential Accuracy [4] ± 0.15 parts per million ± 0.5 parts per million
Minimum Resolvable Separation [3], [4] 10 GHz (equal power lines input)
Calibration Continuous – built-in stabilised single-frequency HeNe laser Continuous – built-in standard HeNe laser
Display Resolution 0.00001 nm 0.0001 nm
Units [5] nm, cm-1, THz
Calibration Accuracy ± 0.5 dB (± 30 nm from 1064, 1310, and 1550 nm)
Linearity [4] ± 0.3 dB (1000 – 1600 nm), lines above -30 dBm
Polorisation Dependence ± 0.5 dB (1000 – 1600 nm)
Display Resolution 0.01 dB
Units dBm, mW, μW
Signal-to-Noise Ratio [4], [6] > 40 dB (100 averages), ≥ 100 GHz channel spacing > 35 dB (100 averages), ≥ 50 GHz channel spacing
Side-Mode-Suppression Ratio [4] > 30 dB at ≥ 0.7 nm from peak
Optical Input Signal
Sensitivity – Single-line input -40 dBm (1270 – 1600 nm), -35 dBm (1000 – 1270 nm), -30 dBm (1600 – 1650 nm)
Sensitivity – Multiple-line input [4] 30 dB below total input power, but not less than single-line input sensitivity
Maximum Power +10 dBm, sum of all lines input (displayed level), +18 dBm, sum of all lines input (safe level)
Return Loss 35 dB (UPC connector), 50 dB (APC connector)
Maximum Number of Lines [7] 1000
Measurement Rate (Time) [8] Option -001: 10 Hz (0.1 s)
Option -002: 6 Hz (0.17 s)
Measurement Modes
Data Mode Single channel, list by wavelength table, list by power table
Delta Mode Difference of measured wavelengths from ITU grid values
Difference of measured wavelengths and powers from user-defined reference channel
Drift Mode Difference between the measured maximum and minimum values of wavelength and power
Difference between the measured current and start values of wavelength and power
Optical input 9/125 μm single-mode fibre (FC/UPC or FC/APC)
Instrument Interface Library of commands (SCPI) via USB 2.0, Ethernet, and optional GPIB
Environmental [4]
Warm-Up Time < 15 minutes None
Temperature +15°C to +30°C (-10°C to +70°C storage)
Pressure 500 – 900 mm Hg
Humidity ≤ 90% R.H. at + 40°C (no condensation)
Dimensions 89 mm x 432 mm x 381 mm
Weight 7.65 kg
Power Requirements 90 – 264 VAC, 47 – 63 Hz, 80 VA max
Warranty 5 years (parts and labour)
[1] Defined as measurement uncertainty, or maximum wavelength error, with a confidence level of ≥ 99.7%.
[2] Traceable to NIST standard (SRM 2517a).
[3] For multi-wavelength measurement, ≥ 20 GHz channel separation is required to achieve specified wavelength accuracy.
[4] Characteristic performance, but non-warranted.
[5] Data in units of nm and cm-1 are given as vacuum values.
[6] For lines above -25 dBm, 0.1 nm noise bandwidth.
[7] OSNR is reduced as the number of lines is increased.
[8] For single-line input. Multiple-line input may reduce the measurement rate.
438 Series Datasheet
438 Series OSA Software

Request a Demo

438 Series

Ask the Expert

If you’re interested in the products shown here, or have questions about something you can’t find on our website, please get in touch through the form below.

Our knowledgeable sales team will be happy to help. We can normally source exactly what you need, or work with you to come up with custom solutions.

Alternatively, just call +44 (0) 1933 461 666 and ask to speak to the Photonics team.