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Fibre Bragg Grating Components for Filtering, Switching and Lasing
KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. (FMI)
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Fibre Bragg gratings (FBGs) are key components for a vast number of applications in optical communication systems, microwave photonics systems, and optical sensors, etc. The main topic of this thesis is fibre Bragg grating fabrication and applications in direct microwave optical filtering, high speed switching and switchable dual-wavelength fibre lasers.

First, a brief overview is given about the photosensitivity in optical fibre, basic FBG fabrication techniques, the popular coupled-mode theory for describing fundamental characteristics of FBGs and the Transfer Matrix method for the numerical simulations of complex-structured FBGs.

An advanced FBG fabrication system based on the technique of multiple printing in fibre (with a continuous-wave source) has been used to write complex FBGs incorporating phase shifts, apodization and chirp.     

A single double-peaked superimposed grating working in reflection can be employed as a direct optical filter for millimetre-wave signals. Bit error rate measurements confirmed that the filter exhibited nearly on-off behaviour in the passband with a 3-dB bandwidth of 2 GHz for a central frequency of 20 GHz, as expected from the optical spectrum reflection. The presented technique can be used in radio-over-fibre systems or simultaneous up-conversion of ultra-wide band signals and filtering.

This thesis focused mostly on the research of two 4-cm long Hamming-apodized gratings written in side-hole fibres with internal electrodes. The temperature dependence measurements showed that the birefringence of the component increased with the temperature. Dynamic measurement has shown nanosecond full off-on and on-off switching. During the electrical pulse action, the grating wavelength was blue-shifted for the x-polarization and red-shifted for the y-polarization due to the mechanical stress. Both peaks subsequently experienced a red-shift due to the relaxation of mechanical stress and the increasing core temperature transferred from the metal in many microseconds. All the wavelength shifts of the two polarizations depend quadratically on the electrical pulse voltage and linearly on the pulse duration. Numerical simulations gave accurate description of the experimental results and were useful to understand the physics behind the birefringence switching.

Finally, two switchable dual-wavelength erbium-doped fibre lasers based on FBG feedback were proposed. In one method, an overlapping cavity for the two lasing wavelengths and hybrid gain medium in the fibre laser were introduced. Dual-wavelength switching was achieved by controlling the Raman pump power. The other method employed an injection technique and the dual-wavelength switching was controlled by the power of the injection laser. The switching time was measured to be ~50 ms. Detailed characteristics of the dual-wavelength switching in the two fibre lasers were experimentally studied and corresponding principles were physically explained.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , xvi, 91 p.
Series
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2008:14
Keyword [en]
fibre Bragg grating, photosensitivity, apodization, chirp, phase-shift, microwave optical filtering
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4896OAI: oai:DiVA.org:kth-4896DiVA: diva2:1805
Public defence
2008-10-03, room N2, Electrum 3, Isafjordsgatan 28, Kista, 10:00 (English)
Opponent
Supervisors
Note
QC 20100922Available from: 2008-09-24 Created: 2008-09-17 Last updated: 2010-09-22Bibliographically approved
List of papers
1. Direct detection of direct optically filtered millimeter-wave signals
Open this publication in new window or tab >>Direct detection of direct optically filtered millimeter-wave signals
2007 (English)In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 19, no 2-4, 233-235 p.Article in journal (Refereed) Published
Abstract [en]

Good performance of a direct optical microwave filter combined with direct detection consisting of a single superimposed grating used in reflection has been assessed through bit-error-rate (BER) measurement. In the passband with a 3-dB bandwidth of 2 GHz, the BER is below 1.2 x 10(-11), showing nearly ON-OFF behavior of the filter.

Keyword
bit-error-rate (BER) measurement, fiber Bragg gratings (FBGs), optical, microwave filtering, microwave, systems
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-16555 (URN)10.1109/lpt.2007.891195 (DOI)000245724000058 ()2-s2.0-72649106053 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
2. High-Speed Control of Fiber Bragg Gratings
Open this publication in new window or tab >>High-Speed Control of Fiber Bragg Gratings
Show others...
2007 (English)In: 2007 Bragg Gratings, Photosensitivity and Poling in Glass Waveguides (BGPP), Optical Society of America, 2007Conference paper, Published paper (Refereed)
Abstract [en]

FBGs were written in fiber with internal alloy electrodes. Nanosecond high current pulses cause metal expansion, increase birefringence and tune the gratings. High-speed wavelength switching was accomplished with potential use in Q-switching fiber lasers.

Place, publisher, year, edition, pages
Optical Society of America, 2007
Series
Optics InfoBase Conference Papers, ISSN 2162-2701
Keyword
Fiber lasers, Glass, Light sensitive materials, Photosensitivity, Q switching, Waveguides, Alloy electrodes, High-current pulse, In-fiber, Wavelength-switching
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-24685 (URN)2-s2.0-84898788502 (Scopus ID)978-155752847-6 (ISBN)1557528470 (ISBN)
Conference
Bragg Gratings, Photosensitivity, and Poling in Glass Waveguides, BGPP 2007, Quebec City, Canada, 2 September 2007 through 2 September 2007
Note

QC 20100922

Available from: 2010-09-22 Created: 2010-09-22 Last updated: 2015-04-16Bibliographically approved
3. Nanosecond switching of fiber Bragg gratings
Open this publication in new window or tab >>Nanosecond switching of fiber Bragg gratings
Show others...
2007 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 15, no 22, 14948-14953 p.Article in journal (Refereed) Published
Abstract [en]

A FBG was written in a two-hole fiber with internal alloy electrodes. Nanosecond high current pulses cause metal expansion, increase birefringence and tune the gratings with a response time of 29 ns. This short length, low loss, all-spliced high-speed wavelength switching devices described here has potential use in Q-switching fiber laser.

Keyword
side-hole fiber, transverse stress, birefringence, temperature, pressure, sensor
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-17131 (URN)10.1364/OE.15.014948 (DOI)000251223400070 ()2-s2.0-35948943175 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
4. Physics of electrically switched fiber Bragg gratings
Open this publication in new window or tab >>Physics of electrically switched fiber Bragg gratings
2008 (English)In: 2008 Conference on Quantum Electronics and Laser Science Conference on Lasers and Electro-Optics, CLEO/QELS, 2008, 580-581 p.Conference paper, Published paper (Refereed)
Abstract [en]

The physics of electrically switched FBGs was studied in fibers with internal electrodes. Wavelength shifts due to mechanical effects (nanoseconds) and heat (milliseconds) depend quadratically on the electrical pulse voltage and linearly on pulse duration.

Keyword
Electron optics, Quantum electronics, Electro-optics, Laser science, Pulse duration
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-24686 (URN)000260498400291 ()2-s2.0-84898618013 (Scopus ID)
Conference
Conference on Lasers and Electro-Optics, CLEO 2008, San Jose, CA, United States, 4 May 2008 through 9 May 2008
Note

QC 20100922

Available from: 2010-09-22 Created: 2010-09-22 Last updated: 2016-12-20Bibliographically approved
5. Birefringence switching of Bragg gratings in fibers with internal electrodes
Open this publication in new window or tab >>Birefringence switching of Bragg gratings in fibers with internal electrodes
2008 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 16, no 11, 8229-8235 p.Article in journal (Refereed) Published
Abstract [en]

A fiber Bragg grating was written in a side-hole fiber with internal metal alloy electrodes. The initial geometrical birefringence of this fiber gives rise to two Bragg resonances separated by 43 pm. Nanosecond risetime current pulses of up to 23 A were applied to the metal electrode, which heated and expanded rapidly. This caused mechanical stress in the fiber on a nanosecond scale, resulting in a negative shift of the Bragg wavelength peak for the fast axis mode, and positive but smaller shift for the slow axis mode. The fast change increased the peak separation to similar to 143 pm, corresponding to an increase in birefringence from 4.0 x 10(-5) to 1.3 x 10(-4). Both peaks subsequently experienced a red-shift due to the relaxation of mechanical stress and the increasing core temperature transferred from the metal in many microseconds. Simulations give accurate description of the experimental results.

Keyword
side-hole fiber, pressure
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-17581 (URN)10.1364/OE.16.008229 (DOI)000256469900070 ()2-s2.0-44649114560 (Scopus ID)
Note

QC 20100525

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
6. High-speed switching in fibres with electrodes
Open this publication in new window or tab >>High-speed switching in fibres with electrodes
Show others...
2007 (English)In: ICTON 2007: Proceedings of the 9th International Conference on Transparent Optical Networks, Vol 1, 2007, 232-233 p.Conference paper, Published paper (Refereed)
Abstract [en]

Fibres with holes are provided with metal electrodes that fill the entire cross-section of the holes. Refractive index change and birefringence result from applying high current pulses for time intervals in the nanosecond range. High-speed polarization rotation and fibre Bragg grating wavelength tuning can be accomplished. Such electrically driven components are totally spliced with low insertion loss. They have no moving parts, are < 10 cm long and can be used in fibre laser cavities for Q-switching.

Keyword
fibre component, microstructured fibre, internal electrodes, high-speed switching, electrical control, fibre lasers
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-24688 (URN)10.1109/ICTON.2007.4296076 (DOI)000250511100063 ()2-s2.0-44649162764 (Scopus ID)1-4244-1249-8 (ISBN)
Note
QC 20100922Available from: 2010-09-22 Created: 2010-09-22 Last updated: 2010-09-22Bibliographically approved
7. Switchable dual-wavelength Raman erbium-doped fibre laser
Open this publication in new window or tab >>Switchable dual-wavelength Raman erbium-doped fibre laser
2006 (English)In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 42, no 4, 202-204 p.Article in journal (Refereed) Published
Abstract [en]

A fibre Bragg grating feedback fibre laser with both Raman and erbium-doped fibre pumps is proposed. Dual-wavelength switching is achieved by controlling the power of the Raman pump. The characteristics of the dual-wavelength switching are studied experimentally, and the mechanism is explained physically.

Keyword
ring laser, cavities
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-15541 (URN)10.1049/el:20064019 (DOI)000236219700009 ()2-s2.0-32944459024 (Scopus ID)
Note

QC 20100525

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
8. Some switchable dual-wavelength fibre lasers based on fibre Bragg grating feedback
Open this publication in new window or tab >>Some switchable dual-wavelength fibre lasers based on fibre Bragg grating feedback
2006 (English)In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6351, U864-U872 p.Article in journal (Refereed) Published
Abstract [en]

Two methods to achieve dual-wavelength switching in a fibre laser are proposed and two corresponding switchable dual-wavelength fibre lasers based on fibre Bragg grating (FBG) feedback are demonstrated in this paper. In one proposed fibre laser, both Raman and Erbium-doped fibre (EDF) pumps are employed and the dual-wavelength switching is achieved by controlling the power of the Raman pump. In the other proposed fibre laser, an injection technique is used and the dual-wavelength switching is realized by controlling the power of the injection laser. The detailed behavior of the dual-wavelength switching in the two fibre lasers is experimentally studied and the principle is explained physically.

Keyword
switchable, dual-wavelength, fibre Bragg grating, fibre laser
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-24689 (URN)10.1117/12.688319 (DOI)000243501300080 ()
Note
QC 20100922Available from: 2010-09-22 Created: 2010-09-22 Last updated: 2017-12-12Bibliographically approved
9. Tunable and injection-switchable erbium-doped fiber laser of line structure
Open this publication in new window or tab >>Tunable and injection-switchable erbium-doped fiber laser of line structure
2007 (English)In: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 49, no 4, 765-768 p.Article in journal (Refereed) Published
Abstract [en]

A tunable and injection-switchable erbium-doped fiber (EDF) laser is proposed based on a line structure formed by a fiber Sagnac loop reflector and an fiber Bragg grating (FBG). Wavelength switching is achieved by controlling the power of the tunable injection laser. The self-seeded wavelength corresponding to the Bragg wavelength of the FBG can be tuned by, for example, heating the FBG, and the injection wavelength can be tuned over a wide range of about 50 nm. The characteristics of the wavelength switching for different levels of the EDF pump power and different wavelengths of the injection laser are studied experimentally. The present fiber laser has the advantages of tunability, stability, low amplified spontaneous emission noise, and high injection efficiency when compared with a fiber ring laser. Rapid wavelength switching is expected and the transient switching response of the laser is also studied.

Keyword
tunable, injection, switchable, line structure, erbium-doped fiber laser, high-birefringence fiber, ring laser, grating cavities, cascaded fiber
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-16455 (URN)10.1002/mop.22262 (DOI)000244964500007 ()2-s2.0-34047195304 (Scopus ID)
Note

QC 20100525

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved

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CiteExportLink to record
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