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| 2. |
- Petermann, Ingemar, et al.
(författare)
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Fabrication of advanced fiber Bragg gratings by use of sequential writing with a continuous-wave ultraviolet laser source
- 2002
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 41:6, s. 1051-1056
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel scheme based on sequential writing for fabrication of advanced fiber Bragg gratings. As opposed to earlier sequential methods this technique uses a cw UV laser source and allows for very precise control and repetitivity of the formation of the gratings. Furthermore it is possible to use high average irradiances without destroying the fiber, resulting in considerable reduction in fabrication time for complex gratings. The method has been applied to several test gratings, which proved its versatility and quality.
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| 3. |
- Petermann, Ingemar, et al.
(författare)
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Fibre Bragg characterization with ultraviolet-based interferometric side diffraction
- 2003
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Ingår i: Journal of Optics. A, Pure and applied optics. - : IOP Publishing. - 1464-4258 .- 1741-3567. ; 5:5, s. 437-441
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Tidskriftsartikel (refereegranskat)abstract
- The interferometric side diffraction method for fibre Bragg grating characterization is evaluated using a set-up with an ultraviolet interrogation beam. In its present configuration, the reproducibility errors are 2-5% for the index and typically 10degrees-20degrees for the phase profile. The reflection spectra of chirped test gratings have been successfully reproduced with the aid of the acquired phase and refractive index envelope data. It is verified that the power of the interrogating beam, within some limits, is unimportant as regards the phase reproducibility, and the importance of relating the analysis to the fabrication parameters of the grating under investigation is stressed.
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| 4. |
- Petermann, Ingemar, 1972-
(författare)
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Fibre Bragg Gratings : Characterization, Realization and Simulation
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main topic of this thesis is realization and characterization of fibre Bragg gratings. A novel versatile grating fabrication technique is developed and a number of gratings are realized, showing the potential of the system. Arbitrarily-shaped gratings are sequentially imprinted in the fibre by a moving interference pattern created with a continuous-wave ultraviolet (UV) source. This scheme allows for a very good control and stability of the grating shape, which is also shown experimentally. As opposed to most other present fabrication techniques, the proposed method offers a total control over the grating parameters by software, enabling simple implementation of new designs. Different kinds of error sources when stitching long gratings are identified and investigated regarding impact on the final grating result. Another important question within this field is how to characterize gratings. We propose a new characterization method based on optical low-coherence reflectometry (OLCR). A new interferometer design allows for simple simultaneous detection of the reflection response from two different points in the interrogated grating, so that differential measurements can be performed. The advantage of this is that the sensitivity to noise caused by e.g. thermal fluctuations in the system is substantially reduced. Several test gratings have been investigated and a very good agreement to the expected results is noted. A second characterization technique using interferometric detection of the side diffraction from the grating under test is investigated both theoretically and experimentally. With aid of two-dimensional theory for wave propagation, it is shown that there is a linear relation between the detected phase and modulation depth and the corresponding grating properties. The technique is evaluated with a novel scheme of implementation where the UV source provided in a fabrication setup is used assource for the side probe. This approach results in a very simple implementation and opens for an integration of the characterization and fabrication systems. Finally, a tuning method for transmission filters based on local heating of linearly chirped fibre Bragg gratings is analysed and further developed to allow for fully software-controlled operation. The potential of this technique is illustrated by some promising initial experimental results.
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| 5. |
- Petermann, Ingemar, et al.
(författare)
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Limitations of the interferometric side diffraction technique for fibre Bragg grating characterization
- 2002
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Ingår i: Optics Communications. - 0030-4018 .- 1873-0310. ; 201:4-6, s. 301-308
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Tidskriftsartikel (refereegranskat)abstract
- We make a quantitative investigation of the interferometric side diffraction technique for characterization of fibre Bragg gratings. As opposed to more commonly used non-interferometric alternatives, this method also allows for determination of the grating's distributed phase. It is shown that for weak gratings the detected power and phase are directly proportional to the amplitude and phase of the refractive index modulation in the fibre. While the phase measurement is only limited by the amount of noise present, the relation between modulation amplitude and detected power becomes non-linear when using small probe beam wavelengths and gratings with a modulation depth Deltan approximate to 10(-3) and above. This behavior is inherent to the side diffraction and thus care has to be taken when performing apodization measurements on very strong gratings. The sensitivity to noise is briefly discussed and using a crude estimate for the noise level. the theory indicates that this method is suitable down to a grating modulation depth of at least Deltan approximate to 10(-5).
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| 6. |
- Petermann, Ingemar, et al.
(författare)
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Stitch error effect on group-delay ripple for long chirped fiber Bragg gratings
- 2005
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 44:20, s. 4375-4383
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Tidskriftsartikel (refereegranskat)abstract
- Different sources of stitch errors are identified and simulated in a 200 mm. long chirped grating. In each case, the effect on the group-delay ripple and transmission spectrum is investigated. The anticipated response in a typical 10 Gbit/s transmission system is specifically considered. From the simulations, it is clear that information about error source and magnitude can be gained directly from the transmission spectrum.
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| 7. |
- Petermann, Ingemar, et al.
(författare)
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Tunable and programmable optical bandpass filter
- 2007
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Ingår i: Journal of Optics. A, Pure and applied optics. - : IOP Publishing. - 1464-4258 .- 1741-3567. ; 9:11, s. 1057-1061
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a novel tunable and programmable optical bandpass filter with a transmission peak less than 5 pm wide that is tunable over 18.5 nm. The number of transmission windows within the stop band, as well as each window's position and strength, is set by applying a heat profile to a chirped fibre Bragg grating with the aid of a thermal printer head comprising a 640 pixel array. It is shown that the width of a transmission peak formed by local heating is mainly determined by the refractive index modulation depth and chirp rate and not by the width of the heated region.
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