As communication channel counts continue to escalate—evolving from the initial 40 wavelengths to currently over 800—the demand for precise wavelength measurement and calibration of tunable lasers has intensified. Since every wavelength requires calibration via a wavelength meter, fast and accurate wavelength testing technology has become essential.

The Semight Instruments FWM8612 Wavelength Meter utilizes Fizeau interferometer technology, integrating a temperature-stabilized interferometer, a multi-stage composite interference cavity, and a linear array CCD detector. Unlike traditional wavelength meters based on Michelson interferometers, the FWM8612 features an all-solid-state architecture with no mechanical moving parts. This design ensures high measurement precision (typical value ±0.5 pm) while achieving a wavelength refresh rate of up to 1 kHz. When combined with external triggering and fast power detection capabilities, the FWM8612 can precisely capture synchronous transient changes in both wavelength and power.

Semight FWM8612 Core Features

• High Wavelength Accuracy:

  Typical accuracy is ±0.5 pm (approx. ± 0.33 ppm). This outperforms standard wavelength meters (such as the Bristol 438B, Yokogawa AQ6150, and Keysight 86120B/C series) and is comparable to the industry's highest precision wavelength meters (0.3 pm), making it suitable for strict wavelength calibration and metrology scenarios.

• High Resolution:

  Achieves a wavelength resolution of 0.1 pm (approx. 12.5 MHz).

• All-Solid-State High-Speed Measurement:

  With no mechanical moving parts and a refresh rate of 1 kHz, the device is ideal for transient wavelength and power testing. This significantly enhances testing efficiency for iTLA, DBR, and coherent communication modules.

• Broadband Testing Capability:

  Supports precise wavelength measurement of 96 GBaud modulated optical signals.

• Advanced Analysis Functions:

  Includes support for wavelength drift testing and the display of maximum/minimum values.

• Flexible Triggering & Synchronization:

  Supports both internal and external triggering (5V TTL). FPGA-based implementation ensures synchronous acquisition of wavelength and power data, allowing for synergistic operation with precision Source Measure Units (SMUs) to guarantee data accuracy.

• Excellent Compatibility:

  Supports SCPI standard commands and is compatible with mainstream instrument control protocols (e.g., Keysight, Yokogawa).

• Wide Applicability:

  Suitable for wavelength and power testing of various optical device formats, including CoC, TOSA, and Modules.

Typical Application Scenarios

Scenario 1: Single Sampling Mode

In single sampling mode, the FWM8612 achieves a sampling rate of up to 200 Hz. This is 20 to 100 times faster than traditional wavelength meters based on Michelson interferometers. It maintains power accuracy better than 0.5 dB with repeatability less than 0.02 dB.

FWM8612 Single Sampling Mode Test Results

Scenario 2: Internal Trigger Sampling Mode

The device includes a built-in trigger signal generator supporting a measurement rate of up to 1000 Hz. This mode is effective for monitoring optical switch changeover cycles and stability, as well as capturing transient wavelength and power variations in tunable lasers.

FWM8612 Internal Trigger Sampling Mode

Scenario 3: External Trigger Sampling Mode

Supporting 1000 Hz external trigger sampling, this mode is designed for the synchronous measurement of tunable laser scanning spectra, ModeMap scanning, and channel calibration. It is also suitable for the synchronous monitoring of wavelength and power in pulsed lasers.

FWM8612 External Trigger Sampling Mode

FWM8612 Tunable Laser Mode Map Test

Scenario 4: Broadband Operating Mode

Traditional wavelength meters are typically designed to calibrate and test unmodulated, narrow linewidth lasers. They face significant challenges when measuring the precise wavelength of spectra broadened by high-speed modulation (e.g., 96 GBaud modulation resulting in a bandwidth of up to 96 GHz).

Common multi-wavelength meters (such as the Keysight 86122C or Yokogawa AQ6151B) often struggle to maintain accuracy when the modulation linewidth exceeds 2.5 GHz. Through system optimization, the FWM8612 achieves precise wavelength measurement for broadband modulated signals, such as 400G QAM16 (96 GBaud), delivering superior performance in long-term stability tests compared to traditional equipment.

Unmodulated Laser Signal Spectrum [Left] vs. 

Modulated Laser Spectrum Broadening [Right]

Conclusion

With its high precision, rapid measurement speed, and exceptional stability, the Semight Instruments FWM8612 provides a reliable measurement solution for tunable laser calibration, high-speed modulated signal testing, and optical device R&D, fully meeting the testing demands of current and future high-speed optical communication systems.