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Sub-picometer resolution for validating tightly spaced optical channels
Keysight XP2-class wavelength meters provide fast, accurate, and traceable wavelength measurements of dense wavelength division multiplexing (DWDM) signals for calibrating tunable transmitter lasers. Featuring high resolution and repetition rate, our wavelength meters are designed to meet the stringent demands of R&D labs, manufacturing lines, and calibration environments where absolute wavelength accuracy is critical. With wide wavelength coverage and sub-picometer resolution, Keysight wavelength meters ensure compliance with International Telecommunication Union (ITU) grids, minimize drift-related errors, and accelerate tuning and validation tasks. Select the wavelength meter you need based on the wavelength range and absolute wavelength accuracy level you require. Choose one of our popular configurations or configure one specific to your application.
Sub-picometer accuracy
Achieve ultra-fine wavelength resolution with absolute accuracy down to ±0.2 ppm, ideal for tightly spaced ITU channel validation and fine spectral tuning.
Fast update rates
Real-time wavelength display and fast measurement speeds enable closed-loop laser tuning and high-throughput manufacturing workflows.
Broad wavelength coverage
Covers multiple optical wavelength ranges across C, L, and O bands to support diverse applications from optical communications to photonics.
Traceable calibration
Factory-calibrated to international standards with long-term stability and low drift to provide you confidence in every wavelength measurement.
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Wavelength range
1270 nm to 1650 nm, 700 nm to 1650 nm
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Absolute wavelength accuracy
± 0.2 ppm to ± 1 ppm
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Measurement cycle time
0.3 s to 0.6 s
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Minimum resolvable line separation
5 GHz to 15 GHz
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Best power accuracy
± 0.5 dB to ± 0.6 dB
Most popular configurations
XP2-class Wavelength Meter, multi-wavelength support
XP2-class Wavelength Meter, multi-wavelength support
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Frequently asked questions
A wavelength meter is a high-precision optical instrument used to measure the central wavelength of laser sources or broadband light emitters. It operates by capturing the incoming optical signal and analyzing its interference pattern. The instrument then calculates the wavelength, often with sub-picometer accuracy, based on this interference pattern. Some wavelength meters also provide real-time measurements of power, wavelength drift, and mode stability.
These tools are essential for applications where laser wavelength accuracy, spectral stability, and ITU grid alignment are critical, such as in DWDM (Dense Wavelength Division Multiplexing) systems, tunable laser source calibration, and optical component validation. Modern wavelength meters are typically factory-calibrated and offer traceability to international standards to ensure long-term measurement accuracy and confidence.
Wavelength meters are used across a wide range of optical test applications in both R&D and manufacturing environments. Common use cases include:
- Tunable laser calibration: Ensure the laser source is tuned to the correct wavelength for telecom, photonics, or quantum applications.
- DWDM channel verification: Validate that each channel in a DWDM system complies with standardized ITU-T grid spacing, often with sub-picometer resolution.
- Spectral tuning and validation: Measure and adjust the output of optical transmitters, modulators, or photonic integrated circuits (PICs) during test and alignment.
- Long-term wavelength stability monitoring: Track laser drift over time in environments requiring continuous performance, such as metrology labs or quantum experiments.
In each of these use cases, a wavelength meter ensures spectral precision, system compliance, and device repeatability, which are critical for high-speed optical communication and photonic systems.
When selecting a wavelength meter, the best choice depends on how precisely and how quickly you need to characterize your light source. Here are the most important specifications to consider, and how each one affects performance in optical test and measurement environments:
- Wavelength range: Make sure the meter supports the spectral band your lasers or optical sources operate in. For telecom and datacom testing, look for coverage across the C-band (1530–1565 nm), L-band (1565–1625 nm), or even the full 1260–1650 nm window. If you're working in other regions, ensure the model includes those wavelengths. Choosing the correct range ensures full compatibility with your light sources and avoids signal clipping or undetected drift.
- Wavelength accuracy: For high-density WDM systems, narrow linewidth lasers, or applications requiring ITU-grid compliance, high accuracy is essential. Greater accuracy improves alignment, tuning precision, and long-term reliability of your system.
- Measurement cycle time: Also referred to as measurement speed or update rate, this determines how quickly the instrument provides a new wavelength reading. In dynamic test environments or automated production lines, faster cycle times enable real-time tuning, laser locking, or in-process pass/fail checks without slowing down your workflow.
- Resolvable line separation: This defines the instrument’s ability to distinguish two closely spaced spectral lines. A wavelength meter with fine resolvable line separation can differentiate closely spaced DWDM channels or detect multiple modes in multi-line laser sources. This is particularly important for spectral purity analysis and verifying modulated signals.
- Power accuracy: Many wavelength meters also report absolute optical power. This ensures meaningful power readings, especially when integrating wavelength and power data in a feedback control loop.
- Calibration traceability: For any application that requires compliance, traceability, or long-term measurement confidence, it’s essential to choose a meter with factory calibration traceable to international standards like NIST. Traceable calibration supports quality assurance, regulatory audits, and measurement repeatability across teams or labs.
By evaluating these core specifications, you can select a wavelength meter that aligns precisely with your optical testing requirements whether you're working in telecom system integration, tunable laser development, quantum optics, or production test of photonic components.