Author Affiliations
1National Key Laboratory of Science and Technology on Space Microwave, China Academy of Space Technology-Xian, Xian, Shaanxi 710100, China2Key Laboratory of Space Laser Communication and Detection Technology, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, 201800, China3Beijing Institute of Tracking and Telecommunication, Beijing 100094, Chinashow less
Fig. 1. Schematic diagram of an MPSFBG
Fig. 2. Spectra of MPSFBGs with 2, 4, and 6 phase shifts. The ratios of the lengths of subgratings are (a) 1∶1∶1, 1∶1 ∶1 ∶1 ∶1, and 1∶1∶1∶1∶1∶1∶1; (b)3∶1∶3, 3∶1∶1∶1∶3, and 3∶1∶1∶1∶1∶1∶3; (c) 1∶2∶1, 1∶2.3∶2.6∶2.3∶1, and 1∶2.2∶2.6∶2.7∶2.6∶2.2∶1, respectively
Fig. 3. Simulated transmission spectra and parametric curves of MPSFBGs with different number of phase shifts when the 3 dB bandwidth of filters is 500 MHz. (a) Spectra of MPSFBGs; (b) shape factor of filter and the tolerance of phase shifts location versus the number of phase shifts of MPSFBG
Fig. 4. Bandwidth and shape factor of filter versus coupling coefficient κ of MPSFBG when the length of MPSFBG is 30 mm. (a) Bandwidth; (b) shape factor
Fig. 5. Bandwidth of filter and shape factor of filter versus coupling length l of MPSFBG
Fig. 6. Influence of process errors on the spectrum of double-phase-shifted FBG. (a) Length ratio of fiber grating; (b) phase shifts δφ
Fig. 7. Experimental principle. (a) Schematic of inscription system with the phase mask; (b) schematic diagram of MPSFBGs inscription
Fig. 8. Tolerance of phase shifts position versus the bandwidth of transmission peak
Fig. 9. Spectra of double-phase-shifted FBG prepared. (a) Without phase shift error; (b) with phase shift error
Fig. 10. Tolerance of differences between phase shifts versus bandwidth of transmission peak
Fig. 11. Spectrum of double-phase-shifted FBG with the coupling coefficient of 225 m-1 and the length of 30 mm
Fig. 12. Spectra of triple-phase-shifted FBG with different parameters. (a) Coupling coefficient of 225 m-1, the length of 30 mm, loss coefficient of 0.72 m-1; (b) coupling coefficient of 330 m-1, the length of 30 mm, loss coefficient of 1 m-1
Fig. 13. Change in the tolerance of position of phase shifts and the tolerance of differences between phase shifts versus the length of the fiber gratings. (a) Tolerance of phase shifts position; (b) tolerance of differences
Fig. 14. Loss of transmission peak versus length of the fiber gratings considering UV-induced loss
Number of phase shifts | Ratio |
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2 | 1∶2 ∶1 | 3 | 1∶2.25∶2.25∶1 | 4 | 1∶2.3∶2.6∶2.3∶1 | 5 | 1∶2.25∶2.55∶2.55∶2.25∶1 | 6 | 1∶2.25∶2.55∶2.6∶2.55∶2.25∶1 | 7 | 1∶2.2∶2.48∶2.55∶2.55∶2.48∶2.2∶1 | 8 | 1∶2.15∶2.48∶2.6∶2.63∶2.6∶2.48∶2.15∶1 |
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Table 1. Ratios of the lengths of each subgratings in the MPSFBGs