Spelling suggestions: "subject:"laser como""
1 |
Laser a fibra dopada com Érbio com múltiplos comprimentos de onda e múltiplos regimes de operação simultâneosSantos, Cláudia Barros dos 21 January 2011 (has links)
Made available in DSpace on 2016-03-15T19:37:34Z (GMT). No. of bitstreams: 1
Claudia Barros dos Santos.pdf: 3294972 bytes, checksum: b848d69d9c6a8c824e5142a4e3659d37 (MD5)
Previous issue date: 2011-01-21 / In this work, we inserted two Arrayed Waveguide Gratings (AWGs), in an Erbium doped fiber ring cavity laser, where a single gain medium at room temperature can emit laser in multiples wavelengths, simultaneous and individualy controlled. The setup allowed us to check different functions in the ring cavity. Here we show emission in CW regime, Passive Mode-Locking, using Carbon Nanotubes as saturable absorbers and finally Active mode-locking at 7GHz, simultaneously. / Neste trabalho, fez-se a inserção de duas grades de difração matriciais com guias de onda, ou AWGs (Arrayed Waveguide Gratings) em uma cavidade laser de fibra dopada com Érbio, onde um único meio de ganho em temperatura ambiente pode gerar ação laser em múltiplos comprimentos de onda, com emissões simultâneas e controladas individualmente. A configuração utilizada permitiu o teste com diferentes regimes de operação simultâneos dentro da cavidade. Mostramos a possibilidade de emissão laser em regime CW, em regime de mode-locking passivo, com o uso de nanotubos de carbono como absorvedor saturável e, por último, em regime de modelocking ativo com uma freqüência de modulação de 7 GHz.
|
2 |
Laser a fibra dopada com Érbio com múltiplos comprimentos de onda e múltiplos regimes de operação simultâneosSantos, Cláudia Barros dos 21 January 2011 (has links)
Made available in DSpace on 2016-03-15T19:37:35Z (GMT). No. of bitstreams: 1
Claudia Barros dos Santos.pdf: 3294972 bytes, checksum: b848d69d9c6a8c824e5142a4e3659d37 (MD5)
Previous issue date: 2011-01-21 / In this work, we inserted two Arrayed Waveguide Gratings (AWGs), in an Erbium doped fiber ring cavity laser, where a single gain medium at room temperature can emit laser in multiples wavelengths, simultaneous and individualy controlled. The setup allowed us to check different functions in the ring cavity. Here we show emission in CW regime, Passive Mode-Locking, using Carbon Nanotubes as saturable absorbers and finally Active mode-locking at 7GHz, simultaneously. / Neste trabalho, fez-se a inserção de duas grades de difração matriciais com guias de onda, ou AWGs (Arrayed Waveguide Gratings) em uma cavidade laser de fibra dopada com Érbio, onde um único meio de ganho em temperatura ambiente pode gerar ação laser em múltiplos comprimentos de onda, com emissões simultâneas e controladas individualmente. A configuração utilizada permitiu o teste com diferentes regimes de operação simultâneos dentro da cavidade. Mostramos a possibilidade de emissão laser em regime CW, em regime de mode-locking passivo, com o uso de nanotubos de carbono como absorvedor saturável e, por último, em regime de modelocking ativo com uma freqüência de modulação de 7 GHz.
|
3 |
Laser de fibra dopada com érbio multifuncionalDemori, Cláudia Barros dos Santos 25 August 2015 (has links)
Made available in DSpace on 2016-03-15T19:38:55Z (GMT). No. of bitstreams: 1
CLAUDIA BARROS DOS SANTOS DEMORI.pdf: 3640553 bytes, checksum: 13700107293ec12ced27c0e70d6fb334 (MD5)
Previous issue date: 2015-08-25 / This work shows an Erbium doped-fiber Laser with many frequencies and many
operation regimes based on integration of two paired arrayed waveguide gratings
(AWGs) into a ring cavity. The AWGs are highlighted, since 2000, as key technology
for multifrequencies lasers for optical communications, spectroscopy, image, astronomy
and others applications. Fundamentally, gratings work splitting waveguide signal and
since insertion in the cavity they allow simultaneous operating of tens of wavelength.
We explore each one of these wavelength withing Erbium gain region, doing channels
in different regimes of operation. These regimes may be continuous or pulsed. The
advantage is that each channel may be modulated independently. Simultaneous
operation with high repetition rates at 10 and 40 GHz were demonstrated, as continuous
wave. The laser is stable, versatile and multifunctional. It is possible that more
operating regimes, as passive mode-locking, be explored. We showed by this work
efficient way to passive mode-locking by carbon nanotubes as saturable absorbers.
Soon, the passive mode-locking is a potential regime for the demonstrated laser. As the
new bi-dimensional materials, that look efficient for passive mode-locking and in the
future, hybrid mode-locking, as graphene and black phosphor. / Esta tese trata de demonstrar um Laser de fibra dopada com Érbio com múltiplas
frequências e múltiplos regimes de operação simultâneos baseados na integração de
duas grades de difração pareadas (Arrayed Waveguide Gratings, AWGs) dentro de uma
cavidade de laser de fibra. As AWGs são apontadas, desde o ano 2000, como tecnologia
fundamental em lasers de múltiplas frequencias para as comunicações ópticas, para
espectroscopia, imageamento, astronomia, e outras aplicações. Fundamentalmente, as
grades funcionam como divisores do sinal óptico e quando inseridas dentro da cavidade
de um laser de fibra permitem a operação simultânea de dezenas de comprimentos de
onda. Neste trabalho, exploramos cada comprimento de onda, dentro da região de ganho
do Érbio, com um regime de operação diferente. Esse regime pode ser pulsado ou
contínuo. A vantagem do laser apresentado é que cada comprimento de onda é um canal
que pode ser modulado de forma independente. Pôde-se demonstrar operação
simultânea com regimes a altas taxas de repetição como 10 GHz e 40 GHz, assim como
CW. O laser é estável, versátil e multifuncional. É possível que mais regimes de
operação, como o regime de acoplamento de modos passivo sejam explorados.
Mostramos ao longo deste trabalho maneiras eficientes de acoplar modos passivamente,
utilizando nanotubos de carbono como absorvedores saturáveis, logo a técnica de
acoplamento de modos passivo é um dos regimes em potencial para este laser. Assim
como, o uso de novos materiais bidimensionais, que se mostram eficientes para o
acoplamento de modos passivo e futuramente híbrido, como o grafeno e o fósforo
negro.
|
4 |
Liquid Crystal Optics For Communications, Signal Processing And 3-d Microscopic ImagingKhan, Sajjad 01 January 2005 (has links)
This dissertation proposes, studies and experimentally demonstrates novel liquid crystal (LC) optics to solve challenging problems in RF and photonic signal processing, freespace and fiber optic communications and microscopic imaging. These include free-space optical scanners for military and optical wireless applications, variable fiber-optic attenuators for optical communications, photonic control techniques for phased array antennas and radar, and 3-D microscopic imaging. At the heart of the applications demonstrated in this thesis are LC devices that are non-pixelated and can be controlled either electrically or optically. Instead of the typical pixel-by-pixel control as is custom in LC devices, the phase profile across the aperture of these novel LC devices is varied through the use of high impedance layers. Due to the presence of the high impedance layer, there forms a voltage gradient across the aperture of such a device which results in a phase gradient across the LC layer which in turn is accumulated by the optical beam traversing through this LC device. The geometry of the electrical contacts that are used to apply the external voltage will define the nature of the phase gradient present across the optical beam. In order to steer a laser beam in one angular dimension, straight line electrical contacts are used to form a one dimensional phase gradient while an annular electrical contact results in a circularly symmetric phase profile across the optical beam making it suitable for focusing the optical beam. The geometry of the electrical contacts alone is not sufficient to form the linear and the quadratic phase profiles that are required to either deflect or focus an optical beam. Clever use of the phase response of a typical nematic liquid crystal (NLC) is made such that the linear response region is used for the angular beam deflection while the high voltage quadratic response region is used for focusing the beam. Employing an NLC deflector, a device that uses the linear angular deflection, laser beam steering is demonstrated in two orthogonal dimensions whereas an NLC lens is used to address the third dimension to complete a three dimensional (3-D) scanner. Such an NLC deflector was then used in a variable optical attenuator (VOA), whereby a laser beam coupled between two identical single mode fibers (SMF) was mis-aligned away from the output fiber causing the intensity of the output coupled light to decrease as a function of the angular deflection. Since the angular deflection is electrically controlled, hence the VOA operation is fairly simple and repeatable. An extension of this VOA for wavelength tunable operation is also shown in this dissertation. A LC spatial light modulator (SLM) that uses a photo-sensitive high impedance electrode whose impedance can be varied by controlling the light intensity incident on it, is used in a control system for a phased array antenna. Phase is controlled on the Write side of the SLM by controlling the intensity of the Write laser beam which then is accessed by the Read beam from the opposite side of this reflective SLM. Thus the phase of the Read beam is varied by controlling the intensity of the Write beam. A variable fiber-optic delay line is demonstrated in the thesis which uses wavelength sensitive and wavelength insensitive optics to get both analog as well as digital delays. It uses a chirped fiber Bragg grating (FBG), and a 1xN optical switch to achieve multiple time delays. The switch can be implemented using the 3-D optical scanner mentioned earlier. A technique is presented for ultra-low loss laser communication that uses a combination of strong and weak thin lens optics. As opposed to conventional laser communication systems, the Gaussian laser beam is prevented from diverging at the receiving station by using a weak thin lens that places the transmitted beam waist mid-way between a symmetrical transmitter-receiver link design thus saving prime optical power. LC device technology forms an excellent basis to realize such a large aperture weak lens. Using a 1-D array of LC deflectors, a broadband optical add-drop filter (OADF) is proposed for dense wavelength division multiplexing (DWDM) applications. By binary control of the drive signal to the individual LC deflectors in the array, any optical channel can be selectively dropped and added. For demonstration purposes, microelectromechanical systems (MEMS) digital micromirrors have been used to implement the OADF. Several key systems issues such as insertion loss, polarization dependent loss, wavelength resolution and response time are analyzed in detail for comparison with the LC deflector approach. A no-moving-parts axial scanning confocal microscope (ASCM) system is designed and demonstrated using a combination of a large diameter LC lens and a classical microscope objective lens. By electrically controlling the 5 mm diameter LC lens, the 633 nm wavelength focal spot is moved continuously over a 48 [micro]m range with measured 3-dB axial resolution of 3.1 [micro]m using a 0.65 numerical aperture (NA) micro-objective lens. The ASCM is successfully used to image an Indium Phosphide twin square optical waveguide sample with a 10.2 [micro]m waveguide pitch and 2.3 [micro]m height and width. Using fine analog electrical control of the LC lens, a super-fine sub-wavelength axial resolution of 270 nm is demonstrated. The proposed ASCM can be useful in various precision three dimensional imaging and profiling applications.
|
Page generated in 0.0664 seconds