Hui Yan, and Jingsong Wei, "False nonlinear effect in z-scan measurement based on semiconductor laser devices: theory and experiments," Photonics Res. 2, 51 (2014)
- Photonics Research
- Vol. 2, Issue 2, 51 (2014)

Fig. 1. Schematic of the far-field external cavity feedback influence on an LD: (a) detailed external feedback structure, (b) effective internal LD structure.

Fig. 2. Relationship among P 2 , R eff , and R 3 at different R 2 values: (a) dependence of R eff on R 3 , (b) dependence of P 2 on R 3 .

Fig. 3. Geometric simplification of laser beam propagation at different sample positions: (a) before the focal plane, (b) on the focal plane, (c) after the focal plane.

Fig. 4. Normalized reflected light power P reflect using geometrical and Gaussian optics.

Fig. 5. Scheme of the z -scan equipment and its improvement.

Fig. 6. Relationship among LD output power, P noise , and sample position z : (a) normalized P noise in z scan, (b) dependence of P noise on LD power.

Fig. 7. Detailed illustration of the effective LD output with an attenuator.

Fig. 8. Relationship of R eff 2 and P 2 with different attenuations in z scan when R 2 = 0.3 : (a) dependence of R eff 2 on R 3 , (b) dependence of P 2 on the z position.

Fig. 9. Comparison of feedback influence with different attenuation values.

Fig. 10. Reduction of feedback light influence on open-aperture z -scan measurement: (a) z -scan experimental setup, (b) transmittance with and without an opto-isolator unit, (c) T z - scan / P noise with and without an opto-isolator unit.

Fig. 11. Reduction of feedback light influence on closed-aperture z -scan measurement: (a) transmittance with and without an opto-isolator unit, (b) T z - scan / P noise with and without an opto-isolator unit.

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