As core components of modern optoelectronic technology, the accuracy of a laser’s wavelength and power parameters directly affects application performance and safety. Whether in industrial processing, medical aesthetics, LiDAR, or optical communications, precise testing of wavelength and power is the foundation for ensuring performance.
I. Definition of Laser Wavelength and Power
Laser wavelength refers to the peak wavelength corresponding to the maximum power in the laser radiation spectrum, commonly expressed in nanometers (nm). It determines the color of the laser and its interaction characteristics with materials. Laser power refers to the radiant energy output per unit time. For continuous‑wave lasers, it is commonly expressed in watts (W) or milliwatts (mW) and is the core indicator of laser “intensity”. For pulsed lasers, in addition to average power, parameters such as pulse energy, peak power, and pulse width must also be considered.
II. Testing Standards Framework
Laser testing must comply with a series of domestic and international standards to ensure accuracy and mutual recognition:
Wavelength testing standards:
ISO 13695:2004 – Optics and photonics – Lasers and laser‑related equipment – Test methods for the spectral characteristics of lasers – specifies measurement methods for peak wavelength, center wavelength, spectral bandwidth, and other parameters. This has been adopted as a national standard project in China.
GB/T 15313‑2008 – Laser radiation power and energy measuring instruments – specifies performance requirements for power meters.
Power testing standards:
ISO 11554:2017 – Optics and photonics – Lasers and laser‑related equipment – Test methods for laser beam power, energy and temporal characteristics – covers multiple parameters for continuous‑wave and pulsed lasers.
IEC 60825‑1:2014 – Safety of laser products – includes verification requirements for power and wavelength in safety classification.
In addition, domestic group standards such as T/CVIA 134‑2024 provide detailed specifications for power and wavelength testing methods for semiconductor lasers.
III. Testing Methods and Procedures
1. Power testing methods
Power testing typically uses a laser power meter for direct measurement, in conjunction with a current source and temperature control system. The test steps include: setting up the test setup, aligning the laser and power meter so the beam spot falls within the effective area of the receiver, setting the operating current, and reading the power value after the laser reaches stable operation. For comprehensive performance evaluation, a P‑I‑V (power‑current‑voltage) curve is also plotted to calculate key parameters such as threshold current, slope efficiency, and electro‑optical conversion efficiency.
2. Wavelength testing methods
Wavelength testing mainly uses an optical spectrum analyzer (OSA) or a wavemeter. After coupling the laser into the spectrometer, the scanning parameters are set according to the spectral range of the laser under test, and the wavelength vs. relative spectral intensity distribution is recorded. The wavelength corresponding to the peak intensity is the peak wavelength. For high‑precision wavelength testing, a wavemeter based on Fizeau interferometer technology can achieve wavelength accuracy of ±0.0001 nm. Wavelength stability testing requires continuous recording of wavelength changes over a specified period to evaluate the RMS and peak‑to‑peak values of fluctuations.
3. Standard test procedure
A standard testing procedure generally includes: requirement communication and solution customization → sample preparation and instrument calibration → testing according to standard methods → data analysis and report issuance. Strict environmental temperature control is required during testing, and instruments must be calibrated and within their validity period, with accuracy at least four times better than the error of the measured parameter.
IV. Significance of Testing
Accurate wavelength and power testing is the core of laser quality control. It is critical for laser product safety certification (e.g., IEC 60825 eye safety classification) – wavelength and power directly determine the laser‘s safety class. Moreover, power stability and wavelength stability testing ensure the reliability and consistency of laser equipment in applications such as industrial processing, medical surgery, and optical communications.
V. Professional Testing Body: Shenzhen Zhongwei Inspection
Shenzhen Zhongwei Inspection Technology Co., Ltd. (CTNT) is a professional laser product testing and certification body in South China. The company holds CNAS and CMA accreditations and operates an internationally recognised laboratory. It has more than 70 laser‑related authorised standards and over 120 testing capability parameters, with a measurement power range covering pW to 5 kW and pulse measurement down to the picosecond level.
The company’s services include: laser wavelength testing, power testing, beam quality factor (M²) testing, pulse width testing, as well as laser performance parameter evaluation and laser eye safety certification. With over ten years of experience in laser testing and a track record of serving more than 10,000 customers, it provides one‑stop testing and certification services for industrial, medical aesthetic, LiDAR, research, and other fields.
