VSL Optical Gain Measurement System
MVSLOGMS-266
VSL Optical Gain Measurement System MVSLOGMS-266
 
This measurement system uses the variable stripe length (VSL) method to evaluate the modal optical gain and lasing threshold of epitaxial wafers and laser bars for semiconductor lasers.
A 266 nm pulsed ultraviolet laser (pulse width: 3–5 ns, repetition rate: 10–15 Hz) is used as the excitation source, efficiently photoexciting the sample with high-peak-power ultraviolet pulses. The excitation stripe length can be set continuously with a manual variable slit, and the image of the variable slit is precisely transferred onto the sample surface by an imaging lens and an ultraviolet objective lens in a dedicated ultraviolet microscope optical system.
The length and width of the excitation stripe are calibrated in advance using a stage micrometer and a UV CCD camera. In addition, the irradiation energy at each stripe length is measured with a power meter, and the correlation between stripe length and irradiation energy is obtained, enabling highly quantitative VSL measurements.
Amplified spontaneous emission (ASE) emitted from the sample edge is observed in real time with the UV CCD camera through the ultraviolet microscope, while the ASE spectrum is measured with a spectrometer. The peak intensity (relative intensity) is determined from the ASE spectrum acquired at each stripe length, and the modal optical gain is calculated by analyzing the relationship between stripe length and ASE peak intensity. The lasing threshold can also be evaluated by measurements at varying excitation intensities.
The 266 nm ultraviolet laser has a high photon energy of approximately 4.66 eV, making it suitable for evaluating the optical gain of wide-bandgap semiconductor laser materials, such as GaN-, AlGaN-, and ZnO-based materials. This system is ideal for research and development of semiconductor laser materials, optimization of epitaxial growth conditions, laser structure design, and quality evaluation.

■Features
1. Modal optical gain measurement by the variable stripe length (VSL) method
2. Photoexcitation with a 266 nm pulsed ultraviolet laser (3–5 ns, 15 Hz)
3. Continuously variable excitation stripe length with a manual variable slit
4. Precise transfer of the stripe image by ultraviolet microscope optics
5. Calibration of excitation stripe dimensions with a stage micrometer and a UV CCD camera
6. Calibration of irradiation energy with a power meter
7. Observation of ASE from the laser bar facet with a UV CCD camera
8. ASE spectrum measurement with a spectrometer
9. Calculation of modal optical gain by analyzing stripe length versus ASE peak intensity (relative value)
10. Evaluation of the lasing threshold at varying excitation intensities

■Specifications
Measurement Method Variable stripe length (VSL) method
Excitation Wavelength 266 nm
Irradiation Optics 1 mm × 0.01 mm stripe irradiation optics (variable stripe length)
Optics for observing the irradiated stripe
Measurement Optics UV-visible PL measurement microscope
Spectroscopic System Wavelength range: 200–850 nm
Resolution: 0.952 nm (theoretical value)
Observation System Sensor type: CCD
Optical format: 1/2-type
Effective pixels: 1392 (H) × 1040 (V)

■Image of the Emission Point
Image of the emission point

■Images of the Irradiated Stripe
Image of the irradiated stripe 1 Image of the irradiated stripe 2 Image of the irradiated stripe 3

*Specifications and appearance are subject to change without notice for product improvement.