Multi-wavelength fiber laser with erbium doped zirconia fiber and semiconductor optical amplifier

Multi-wavelength hybrid fiber lasers are demonstrated in both ring and linear cavities using a fabricated Erbium-doped Zirconia fiber (EDZF) and semiconductor optical amplifier (SOA) as gain media. In both configurations, the a fiber loop mirror, which is constructed using a 3 m long polarization maintaining fiber (PMF) and a polarization insensitive 3dB coupler is used as a comb filter for the fiber laser. In the ring cavity, 10 simultaneous lines with peak power above -26 dBm is obtained at 1550 nm region. This is an improvement compared to the linear cavity configuration which has only 5 simultaneous lines observed from wavelength 1556.1 nm to 1563.0 nm with the peak power above -40 dBm. Both hybrid lasers has a constant line spacing of 1.7 nm, which is suitable for wavelength division multiplexing and sensing applications and shows a stable operation at room temperature

Flattening Few Mode Fiber Laser Source Based on PMF and Loop Mirror in a Ring Cavity Resonator

Abstract: A multi-wavelength source using a hybrid amplifier comprised of a Semiconductor Optical Amplifier (SOA) and an Erbium-doped fiber amplifier (EDFA) in a ring fiber laser set up is proposed. Multi-wavelength sources are less expensive and more efficient than deploying several laser diodes at different wavelengths. They are also compact, spend low energy, and emit low heat than multiple laser diode systems. A polarization maintaining fiber (PMF) and an interference comb filter are used in conjunction with the suggested few mode fiber laser source to create higer than 14 wavelength around -28 dBm at a SOA by current near 300 mA and a 980 nm pump power of 95 mW. This source is designed by a combined of EDFA and SOA presented in this report. By altering the birefringence of the ring cavity used as a loop mirror and changing the angle of the plates of the polarization controllers, the number of wavelengths produced may be managed. The suggested fiber laser operates at room temperature and has a constant channel spacing of 0.8 nm, making it appropriate for fiber communication and sensing applications

Carbon nanotubes for ultrafast fibre lasers

Carbon nanotubes (CNTs) possess both remarkable optical properties and high potential for integration in various photonic devices. We overview, here, recent progress in CNT applications in fibre optics putting particular emphasis on fibre lasers. We discuss fabrication and characterisation of different CNTs, development of CNT-based saturable absorbers (CNT-SA), their integration and operation in fibre laser cavities putting emphasis on state-of-the-art fibre lasers, mode locked using CNT-SA. We discuss new design concepts of high-performance ultrafast operation fibre lasers covering ytterbium (Yb), bismuth (Bi), erbium (Er), thulium (Tm) and holmium (Ho)-doped fibre lasers

Photonic devices for integrated optical applications

work presented in this thesis encompasses an investigation into the use of ultrafast laser inscription in the fabrication of glass based photonic devices for integrated optical applications. Waveguide fabrication and characterisation experiments were carried out in three categories of glass substrate. Firstly, waveguides were inscribed in an erbium doped glass with the aim of fabricating optical amplifiers and lasers operating in the 1.5 μm spectral region. Low loss waveguides were fabricated in substrates with different dopant concentrations. Fibre to fibre net gain was achieved from one substrate composition, however it was found that ion clustering limited the amount of achievable gain. Laser action was demonstrated by constructing an optical fibre based cavity around the erbium doped waveguide amplifier. Waveguides were also inscribed in bismuth doped glass with the aim of fabricating optical amplifiers and lasers operating in the 1.3 μm spectral region. Low loss waveguides were fabricated, however the initial composition was incapable of providing gain. A proven substrate material was employed, demonstrating ultra-broadband gain spanning more than 250 nm. High losses prevented the achievement of net gain, however the broad potential of the substrate material was highlighted. Finally, waveguides were inscribed in a Chalcogenide glass. Strong refractive index contrasts were observed, with a wide range of waveguiding structures produced. Supercontinuum experiments were carried out in order to confirm the nonlinear behaviour of the waveguides. A spectrally smooth supercontinuum spanning 600 nm was generated, providing a potentially useful source for optical coherence tomography

Stable multiwavelength erbium-doped random fiber laser

Multiwavelength fiber lasers which consist of equally-spaced frequency components have found many applications and that includes as light sources for optical communication systems. One of the techniques available to generate such multiple wavelengths is random fiber lasers. Despite simplicity in structure due to the avoidance of mirrors in random fiber lasers, the number of comb lines generated is rather limited with only four comb lines are generated within 3 dB flatness at the 60 mW pump power. In optical communication systems, such a limitation in the comb lines could be a hindrance for the attainment of high-speed data communication due to the lack of light sources. Aspired to solve the problems and bring random multiwavelength to new heights, performances of multiwavelength random fiber lasers are improved in this thesis work. Based on the random Rayleigh scattered feedback of a 25 km long single-mode optical fiber, multiwavelength lasers are successfully generated. The linear cavity in which one end is formed by a mirror and the other end by the random Rayleigh scattered feedback is able to generate 27 laser lines within 3 dB flatness at the pump power of 350 mW. In addition, the laser lines generated are also stable with power fluctuations less than 0.6 dB over an hour duration. All in all, the study in this work is found to be effective in elevating the performances of multiwavelength random fiber lasers to further heights

Studies of third-order nonlinearities in materials and devices for ultrafast lasers

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Pages 161-162 blank.Includes bibliographical references (p. 133-143).Recent developments in telecommunications, frequency metrology, and medical imaging have motivated research in ultrafast optics. Demand exists for broadband components and sources as well as highly nonlinear fibers and materials. For this thesis, several different devices have been developed for such applications. Broadband saturable absorbers based on III/V and Si materials systems were developed for femtosecond lasers and have high reflectivity over 200 to 300 nm bandwidths. These absorbers were designed for modulation depths ranging from 0.3% to 18%. Self-starting modelocked operation with the absorbers was achieved in a variety of lasers including Ti:Sapphire, Cr:Forsterite, Er:glass, Cr⁴⁺:YAG and erbium-doped bismuth-oxide fiber. In tapered microstructure fiber, highly nondegenerate four-wave mixing was achieved, with a frequency shift of 6000 cm⁻¹ in an interaction length of only 1.4 cm. Amplification in erbium-doped bismuth-oxide fiber was demonstrated, with gains of 12 dB achieved between 1520 - 1600 nm in a 22.7-cm length. With a 55.6 cm length of bismuthoxide erbium-doped fiber, an L-band modelocked laser was constructed, tunable between 1570 - 1600 nm. It produced 288-fs pulses at 1600 nm. Undoped highly nonlinear bismuthoxide fiber was used to generate smooth, controlled supercontinuum between 1200 to 1800 nm.(cont.) Pulse compression of 150-fs pulses to 25 fs was also demonstrated. Finally, the nonlinear refractive index coefficient and two-photon absorption coefficient of Ge-As-Se glasses were measured. Ge₃₅As₁₅Se₅₀ is found to have a nonlinearity 900 times that of silica.by Juliet Tara Gopinath.Ph.D