A semiconductor mirror exhibiting only induced absorption is used to stabilize a ghz repetition rate active harmonically mode locked fiber laser, improving supermode suppression by eliminating pulse dropouts. Paper v mode locked ytterbium fiber laser tunable in the 9801070 nm spectral range, l. Paper vi 140mhz stretched pulse ytterbium fiber laser. Laser dynamics of a modelocked thuliumholmium fiber laser. A mode locked fiber laser can provide pulse rates and pulse widths suitable for these high bandwidth applications. Finding and investigating alternative low dimensional structures to evaluate their suitability to modelock the fiber laser. In addition to the modelocked fiber laser, a cw and a qswitched fiber lasers were also designed. The phenomena were studied and explained in this dissertation.
Mode locked pulses in passive coherent beam combining fiber laser arrays. The main characteristics of this laser are the singlewavelength tunable operation, multiwavelength tunable operation, and multiwavelength switchable operation. Pdf we performed an experimental investigation on a qswitched, mode locked laser based on the combination of passive q switching and active mode. Widely tunable multiwavelength thuliumdoped modelocked all. Laser built based on fiber technology developed for telecommunications have the potential to address these drawbacks.
In this thesis, a microwave signal generated by beating the mode locked. The aim of this thesis to show beat fiber lasers utilizing a cobaltdoped zinc oxide cozno based saturable absorber. It seems that it took forever to complete this thesis, both the research and the writ ing. Optimization of modelocked fiber lasers by intracavity dispersion compensation and repetition rate stabilization is described.
The adaptive controller, based upon a multiparameter extremumseeking control algorithm, is capable of obtaining and maintaining highenergy, singlepulse states in a modelocked. Then a detailed description on the setup used and the results obtained are shown in chapter 5. Stability analysis of mode locked figureeight fiber laser. Aiming to profit at the same of the two configurations advantages. Modelocked fiber lasers can also be based on ytterbiumdoped fiber for emission somewhere in the range of roughly 1100 nm. In the case of a soliton mode locked fiber laser, the quasisoliton pulses become unstable if the nonlinear effects per resonator round trip become too strong. Washburnthis thesis reports our attempt towards achieving a phase stabilized freespace nonlinear polarization rotation npr mode locked erbium doped fiber laser. Cw laser emits a continuous beam of light as long as medium is excited. All fiber mode locked ultrafast thuliumdoped fiber lasers at 2 m qingqing wang, phd university of pittsburgh, 2014 in this work, we demonstrate three original all. Paper v modelocked ytterbium fiber laser tunable in the 9801070 nm spectral range, l.
In actively mode locked fiber lasers, as shown in fig. Mode locked fiber lasers and their application in microwave. A group at air force research laboratory reported a fiber laser mode locked. In addition to the mode locked fiber laser, a cw and a qswitched fiber lasers were also designed with a single mode multimode single mode sms filter as an effective mean of overcoming nonlinear. In this thesis an accurate method for calculating and characterizing with the amplitude and timing jitters of the nps active mode locked sigma laser. Driven by the applications including optical arbitrary waveform generation, high speed optical sampling, frequency metrology, and timing and frequency distribution via fiber links, low noise fiber laser sources operating at multigigahertz repetition rates are developed systematically. Mode locked fiber lasers are widely used as sources of ultrashort optical pulses. The adaptive controller, based upon a multiparameter extremumseeking control algorithm, is capable of obtaining and maintaining highenergy, singlepulse states in a mode locked. This thesis presents the first dynamic model for the simultaneous coherent combining and mode locking of fiber lasers. The mode locked fiber laser study performed in this thesis can be used to optimize the design and performance of mode locked fiber laser systems.
In this thesis, a multiwavelength passively modelocked fiber ring laser using cascaded fiber bragg gratings is proposed and demonstrated. Laser dynamics of a modelocked thuliumholmium fiber. Larsen and victoria birkedal for proofreading this thesis. Driven by the applications including optical arbitrary waveform generation, high speed optical sampling, frequency metrology, and timing and frequency distribution via fiber links, low noise fiber laser.
Generally, these types of laser cavities provide typically pulses larger than those provided by a passively locked laser. Components for fiber communication and fiber lasers 7. Development of ultrashort pulse fiber lasers for optical. University of southampton research repository eprints soton. We have developed a widely tunable multiwavelength tmdoped mode locked all fiber laser. Nonlinear polarization rotation technique is used where fiber nonlinearity is responsible to mode lock the laser.
Laser dynamics of a mode locked thuliumholmium fiber laser in the solitonic and the stretched pulse regimes. One application of the demonstrated passively mode locked fiber ring laser is to generate highquality microwave signals. Unm optical science and engineering etds engineering etds. We demonstrate an all fiber ultrafast ytterbium laser oscillator mode locked by means of a nonlinear polarization evolution npe method realized in polarizationmaintaining pm fibers. Dec 31, 2019 the aim of this thesis to show beat fiber lasers utilizing a cobaltdoped zinc oxide cozno based saturable absorber. Amplitude and temporal jitter associated with the nps. Wang, qingqing 2014 all fiber mode locked ultrafast thuliumdoped fiber lasers at 2um. Allfiber modelocked ultrafast thuliumdoped fiber lasers. They have the advantages over solidstate pulse lasers in the system robustness, beam quality, pumping efficiency, power. A laser operated in this way is sometimes referred to as a femtosecond laser, for example in modern refractive surgery. Thesis for the degree of doctor of technology to be presented with due permission for public examination.
Modelocking is a technique in optics by which a laser can be made to produce pulses of light of extremely short duration, on the order of picoseconds 10. Modelocked pulses in passive coherent beam combining. The fiber based opo produces counter propagating ultrafast pulses that overlap only twice in the cavity, resulting in a beatnote signal when combined outside of the laser cavity. Determining the most reliable configuration of an ultrafast fiber laser. A laser operated in this way is sometimes referred to as a femtosecond laser. The tunable range of singlewavelength mode locking is 6 nm from 1842 to 1978 nm. This thesis reports work in high repetition rate femtosecond fiber lasers. This thesis presents the first dynamic model for the simultaneous coherent combining and mode locking of fiber. This thesis investigates novel methods of generating ultrashort optical pulses in the visible and ultraviolet wavelength ranges by frequency conversion and supercontinuum generation using modelocked fiber lasers. This thesis investigates novel methods of generating ultrashort optical pulses in the visible and ultraviolet wavelength ranges by frequency conversion and supercontinuum generation using mode locked fiber lasers. Allfiber passively modelocked femtosecond fiber lasers ryerson. The modelocked fiber laser study performed in this thesis can be used to optimize the design and performance of modelocked fiber laser systems.
Active mode locking of raman fiber laser is experimentally investigated for the first time. The development of high power, pulsed fiber laser systems. In addition, cladding pumped fiber allows the efficient conversion of multimode radiation from high power, low cost, broadstripe semiconductor laser diodes into the single mode emission of fiber. Experimental investigation on a qswitched, modelocked fiber laser. At first, the generation of qswitching pulces prepare has been effectively proposed and exhibited utilizing a cobaltdoped zinc oxide cozno nanorods as a sa. Chapter 3 provides an analysis on the theory behind the operation of the mode locked all fiber laser is presented. Chapter 3 provides an analysis on the theory behind the operation of the mode locked all fiber laser is presented with the corresponding model in chapter 4. In this work, active and passive modelocking fiber laser are studied. Simulations of a modelocked fiber laser with a selffocusing, saturable absorber as a passive device. By virtue of the fiber taper tisa, the hybrid edf laser is passively mode locked using the nonlinear polarization evolution npe and emits 70 fs pulses at 1542 nm, whose 3 db spectral width is. Erbium doped fiber laser mode locked by graphene in. Chu city university of hong kong, hongkong abstract mode locked.
Numerical modeling of modelocked fiber lasers with a. It is different from multiwavelength active mode locking in which the roundtrip frequencies for all wavelengths must be identical. Longwave and bicolor typeii inasingasb superlattice infrared detectors, arezou khoshakhlagh. A sequence of the pm fiber pieces is shown to perform npe action while maintaining a required temporal overlap of the ordinary and extraordinary pulses propagating through it. Fabricating low saturation fluence and high modulation depth sesam for fiber laser modelocking at 1 m. The laser operated at a central wavelength of 1558.
Freespace npr mode locked erbrium doped fiber laser based frequency comb for optical frequency measurement by turghun matniyaz b. Cause of many various mechanisms for mode locking, many types of the mode locked laser. Modelocked pulses in passive coherent beam combining fiber. This fiber based mode locker is then spliced into the cavity forming an all fiber mode locked erbium doped fiber laser configuration. Novel technologies for modelocking of solidstate lasers. Today it is used extensively to model pulse propagation in optical fibers 1, 2332. Freespace npr mode locked erbrium doped fiber laser based. This thesis also eases the focus on the saturable absorber, but instead, focusing on the cavity design to generate soliton modelocked fiber lasers. The cpm dye laser was the work horse all through the 1980s for ultrafast laser. The model shows very good agreement with experiment and suggests a novel approach to producing highpeakpower pulse trains with tunable repetition rates in excess of a gigahertz for potential applications to optical clocking, telecommunications, and ultrafast optics. Rareearth doped silica fibers have been used for many years to create continuouswave lasers, and erdoped fiber amplifiers are now widely used in telecommunications.
Widely tunable multiwavelength thuliumdoped modelocked. The increase of saturation fluence by two orders of magnitude for the second excitonic state was clearly shown. Qswitched and modelocked midir fiber lasers by gongwen zhu. Ultrafast laser modelocked using nonlinear polarization. Qswitched and modelocked erbiumdoped fiber laser with. Grudinin, 87th osa annual meeting frontiers in optics, tucson, a rizona, usa, october 2003. Simulations of a mode locked fiber laser with a selffocusing, saturable absorber as a passive device. The growing use of fiber lasers for this purpose is supported by customer demand for reliable femto. Fm modelocked fiber lasers operating in the autosoliton. The all fiber design is realized using a mode fieldadaptor mfa to couple light onto the sesam.
Stable pulses are generated with energies around 0. Reduced graphene oxide as saturable absorbers for erdoped passively mode locked fiber laser grzegorz sobon, 1, jaroslaw sotor, 1 joanna jagiello,2 rafal kozinski,2 mariusz zdrojek, 3 marcin holdynski, 4 piotr paletko, 5 jakub boguslawski, 1 ludwika lipinska, 2 and krzysztof m. Here, a thulium and holmium tmho codoped fiber laser that mode locks in both the solitonic and stretchedpulse regimes is used to produce ultrashort pulses in the 2 mum region. An important difference for this technology, as compared with erbiumdoped lasers, is that the dispersion of silica fibers is normally well in the normal dispersion regime.
Mode locking is a technique in optics by which a laser can be made to produce pulses of light of extremely short duration, on the order of picoseconds 10. Raman dissipative soliton is generated in a mode locked polarization maintaining fiber laser with a nonlinear optical loop mirror. An all fiber connected and polarization maintaining loop cavity of 500 m long is pumped by a linearly polarized 1120 nm yb fiber laser. Firstly, an environmentallystable and ultracompact sesam mode locked fiber laser is demonstrated. An all fiber connected and polarization maintaining loop cavity of 500 m long is pumped by a linearly polarized 1120 nm yb fiber laser and modulated by an acoustooptic modulator. As will be evident throughout this thesis, the development of new modelocked. Modelocked fiber lasers with significant variability of. The subject of this thesis is the investigation of novel technologies for modelocking. Also, the new type of fiber integrated saturable absorber was introduced and the ability to mode lock the fiber laser. Stability analysis of mode locked figureeight fiber laser m. A group at air force research laboratory reported a fiber laser modelocked by multiple quantum well mqw saturable absorber with stable pulses generated as short as 2 ps 21. In this thesis, erbium based modelocked fiber lasers are examined from a development and application point of view.
Pulsed laser emit light only in pulses from femtoseconds to second qswitched laserpulses from micro to nanosecond are produced. Selfstarted mode locked pulses of 400 ns pulse width was successfully realized at a relatively low pump power of 45. A semiconductor mirror exhibiting only induced absorption is used to stabilize a ghz repetition rate active harmonically mode locked fiber laser, improving supermode. Chiang further predicted the possibility of a single mode raman fiber laser in a multimode fiber that could give higher power because of the larger spot size. Below that threshold, characteristic effects such as kelly sidebands can be seen. Numerical modeling of modelocked fiber lasers with a fiber. Interesting facts about modelocked lasers modelocked lasers do not work 99. Ultrafast fiber lasers using novel semiconductor saturable. Paper vi 140mhz stretched pulse ytterbium fiber laser operating in the 9801030. To increase the environmental stability of an npr based mode locked fiber laser, an all polarization maintaining pm fiber design was realized at 1 m recently 1. This dissertation reports on the research to design and build a pulsed fiber laser with the er doped fiber based on a new mode locking technique. The ppktp sample was fabricated by andrius zukauskas and carlota cana. Pulsed laser emit light only in pulses from femtoseconds to second qswitched laser pulses from micro to nanosecond are produced mode locked laser. Jan 27, 2016 mode locked fiber lasers are powerful sources of ultrashort pulses 1,2,3.1090 1278 1250 144 211 331 1543 271 726 106 845 1046 745 178 1103 1590 1492 1302 145 19 1470 1117 645 726 1523 548 311 112 671 1189 365 1283 1027 284 627 1148 402 979