共查询到20条相似文献,搜索用时 31 毫秒
1.
A new quasi-phase-matching technique for efficient second-harmonic generation is reported. It is based on the spatial periodic modulation of the light intensity along the propagation direction, rather than the conventional spatial periodic modulation of the nonlinear optical coefficients. It can be realized by using a novel dual-channel waveguide frequency doubler structure for the desired light intensity distribution. This dual-channel waveguide device has major advantages including very small beam size, high light intensity within long nonlinear-waveguide interaction length, highly efficient second-harmonic generation, ease in fabrication of the nonlinear channel waveguides without any spatially periodic poling, and low waveguide propagation losses. The new quasi-phase-matching technique can also be applied to third-harmonic generation and other nonlinear optics processes. 相似文献
2.
It is known that deep ultraviolet (UV) radiation induces a refractive index increase in the surface layer of polymethylmethacrylate (PMMA) samples. This effect can be used for the fabrication of integrated optical waveguides. PMMA is of considerable interest for bio and chemical sensing applications because it is biocompatible and can be micromachined by several methods, e.g. structuring by photolithography, ablation and hot embossing. In the presented work direct UV irradiation of a common PMMA substrate by a krypton fluoride excimer laser beam through a contact mask has been used to write integrated optical Mach-Zehnder interferometers (MZI). MZI are used as sensitive bio and chemical sensors. The aim was to determine contact mask design and laser irradiation parameters for fabricating single-mode MZI for the infrared region from 1.30 μm to 1.62 μm. Straight and curved waveguides have been generated and characterized to determine the optical losses. The generation of channel waveguide structures has been optimized by a two step irradiation process to minimize the lithographic writing time and optical loss. By flood exposure to UV laser radiation in the first step the optical absorption of PMMA can be increased in the irradiated region. The required refractive index profile is then achieved with a second lithographic irradiation. The spectral behaviour of an unbalanced, integrated optical MZI fabricated by this excimer laser based contact mask method is shown for the first time. Further the optical intensity at the output port of a MZI has been measured while the optical path length difference was tuned by creating a temperature difference between the two arms of the MZI. 相似文献
3.
Hô N Phillips MC Qiao H Allen PJ Krishnaswami K Riley BJ Myers TL Anheier NC 《Optics letters》2006,31(12):1860-1862
We demonstrate the design, fabrication, and characterization of single-mode low-loss waveguides for mid-infrared (MIR) wavelengths. Planar waveguide structures were fabricated from multilayer thin films of arsenic-based chalcogenide glasses followed by the creation of channel waveguides by using the photodarkening effect. Propagation losses as low as 0.5 dB/cm were measured for a quantum cascade laser end-fire coupled into the waveguides. This is a first step toward the design and fabrication of integrated optical components for MIR applications. 相似文献
4.
Masao Kawachi 《Optical and Quantum Electronics》1990,22(5):391-416
A marriage of optical fibre fabrication technology and LSI microfabrication technology gave birth to fibre-matched silica waveguides on silicon: thick glass layers of high-silica-content glass are deposited on silicon by flame hydrolysis, a method originally developed for fibre preform fabrication. Silica channel waveguides are then formed by photolithographic pattern definition processes followed by reactive ion etching. This high silica (HiS) technology offers the possibility of integrating a number of passive functions on a single silicon chip, as well as the possibility of the hybrid integration of both active and passive devices on silicon. This paper reviews the NTT HiS technology and its application to integrated-optic components such as optical beam splitters, optical switches, wavelength-division multi/demultiplexers and optical frequency-division multi/demultiplexers. The clear and simple waveguide structures produced by the HiS technology make it possible to design and fabricate these components with high precision and excellent reproducibility. 相似文献
5.
A. C. Busacca R. L. Oliveri A. C. Cino S. Riva-Sanseverino A. Parisi G. Assanto 《Laser Physics》2007,17(6):884-888
The compatibility of low concentration (α-phase) proton exchange channel waveguides with electric field surface periodic poling of congruent lithium niobate (SPPLN) crystals has been experimentally demonstrated. With such waveguides, we obtained ultraviolet second harmonic generation (SHG) by first order quasi-phase-matching (QPM), a result made possible by the fabrication, on Z-cut LN crystals, of periodic structures with a pitch down to 750 nm. Nonlinear copropagating QPM-SHG measurements have been carried out on such structures. The pump source was a Ti:sapphire laser with a tunability range of 700–980 nm and a 40 GHz linewidth. We have measured UV continuous wave light at 390 nm by means of a lock-in amplifier and a photodiode with an enhanced response in the UV. The measured conversion efficiency was about 1% W?1 cm?2. 相似文献
6.
We report the fabrication of optical channel waveguides in congruent lithium niobate single crystals by direct writing with continuous-wave ultraviolet frequency-doubled Ar+ laser radiation (244 nm). The properties and performance of such waveguides are investigated, and first results are presented. 相似文献
7.
P. V. S. MARQUES P. J. MOREIRA D. ALEXANDRE M. MELO T. E. A. SCHMIDT R. MUENZNER 《Fiber and Integrated Optics》2013,32(3-4):149-169
Abstract This article presents results of device fabrication using UV processing of materials and integrated optic components produced by flame hydrolysis deposition and hybrid sol-gel technology. Photosensitive materials were employed in the fabrication of channel waveguides and channel photo-imprinted waveguides incorporating Bragg gratings through single and double-step exposure. 相似文献
8.
A new type of wavelength selective filter, based on high differential dispersion between two coupled waveguides, is presented. The Bragg Reflection Waveguide displays high effective refractive index dispersion, due to the interaction of the guided mode with the two confining Bragg reflectors. When coupled with a weakly guided buried channel silica waveguide, a very narrow bandwidth filter (<1 nm) can be easily produced, in a shorter length, with respect to directional couplers made with standard step index channel waveguides. The complete design methodology, fabrication and characterization are presented. 相似文献
9.
R. Osellame R. Ramponi M. Marangoni G. Tartarini P. Bassi 《Applied physics. B, Lasers and optics》2001,73(5-6):505-509
A novel configuration is proposed for an all-optical device performing two key functionalities in a communication network
based on wavelength-division-multiplexing (WDM): reconfigurable add/drop and wavelength shifting of single channels. The device
is based on guided second-order nonlinear interactions, such as sum-frequency generation and difference-frequency generation,
between the WDM channels and a suitable pump beam. A directional coupler and two parallel waveguides allow the spatial separation
between the main WDM signal and the dropped or wavelength-shifted channel for a subsequent routing in the desired path. A
first numerical simulation provided a cross-talk level in the dropped channel lower than -41 dB and a wavelength-shifting
range of more than 40 nm.
Received: 18 May 2001 / Published online: 30 October 2001 相似文献
10.
11.
This Letter reports on the fabrication of low-loss waveguides in gallium-lanthanum-sulfide chalcogenide glasses using an ultrafast laser. Spatial beam shaping and temporal pulse width tuning were used to optimize the guided mode profiles and optical loss of laser-written waveguides. Highly symmetric single-mode waveguides guiding at 1560 nm with a loss of 0.65 dB/cm were fabricated using 1.5 ps laser pulses. This Letter suggests a pathway to produce high quality optical waveguides in substrates with strong nonlinearity using the ultrafast laser direct writing technique. 相似文献
12.
Yao Zhang 《Optics Communications》2010,283(10):2140-276
A polarization beam splitter with wide bandwidth and simple structure in air-hole-based periodic dielectric waveguides has been proposed and designed. Operation principle of the device is based on different directional coupling properties of beams in TE and TM polarizations in parallel periodic dielectric waveguides. Performances have been evaluated by a finite-difference time-domain simulation. Results show that the polarization beam splitter provides a wide bandwidth of 113 nm with both a high extinction ratio (higher than 21 dB) and a low insertion loss (less than 1.5 dB) for optical communication wavelengths at ∼1.55 μm. Moreover, the performances of the polarization beam splitter are insensitive to longitudinal alignment errors in the coupling region, which is desirable for device fabrication and practical application. 相似文献
13.
14.
C. L. Sones K. S. Kaur P. Ganguly D. P. Banks Y. J. Ying R. W. Eason S. Mailis 《Applied Physics A: Materials Science & Processing》2010,101(2):333-338
We propose a rapid prototyping method for the fabrication of optical waveguides based on the direct laser-printing method
of ultrafast Laser-Induced Forward Transfer (LIFT) followed by further processing. The method was implemented for the fabrication
of titanium in-diffused lithium niobate channel waveguides and X-couplers by LIFT-depositing titanium metal followed by diffusion.
Propagation loss as low as 0.8 dB/cm was measured in preliminary experiments. 相似文献
15.
Y.N. Korkishko V.A. Fedorov A.N. Alkaev F. Laurell 《Applied physics. B, Lasers and optics》2001,73(5-6):519-522
A detailed correlation between the fabrication conditions, crystallographic phase state of HxLi1-xTaO3 waveguides and second-order optical non-linearity has been investigated by using reflected SHG measurements from the polished
waveguide end face. The non-linearity, strongly reduced after the initial proton exchange, is found to be restored and even
increased after annealing. However, this apparent increase in the non-linearity is accompanied by a strong degradation of
the quality of the SHG reflected beam in the region of the initial as-exchanged waveguide due to beam scattering. The high
temperature proton exchange technique has been shown to produce high-quality α-phase waveguides with essentially undegraded
non-linear optical properties. There is no phase transition when the α-phase waveguides are fabricated by direct exchange.
This phase presents the same crystalline structure as that of LiTaO3 and maintains the excellent non-linear properties of the bulk material. The results obtained are important for the design,
fabrication and optimization of guided-wave non-linear optical devices in LiTaO3.
Received: 21 May 2001 / Published online: 23 October 2001 相似文献
16.
P. V. S. Marques P. J. Moreira D. Alexandre M. Melo T. E. A. Schmidt R. Muenzner A. M. P. Leite J. S. Aitchison 《Fiber and Integrated Optics》2005,24(3):149-169
This article presents results of device fabrication using UV processing of materials and integrated optic components produced by flame hydrolysis deposition and hybrid sol-gel technology. Photosensitive materials were employed in the fabrication of channel waveguides and channel photo-imprinted waveguides incorporating Bragg gratings through single and double-step exposure. 相似文献
17.
David H. Naghski Joseph T. Boyd Howard E. Jackson Andrew J. Steckl 《Optics Communications》1998,150(1-6):97-100
Optical channel waveguides formed by focused ion beam (FIB) implantation-induced mixing of AlGaAs multiple quantum well structures and subsequent oxidation of the mixed regions have the potential of significantly reducing the size of integrated photonic waveguide structures. Since FIB implantation is a direct write process characterized by nanoscale precision, we suggest its use for forming channel waveguides having nanoscale (submicrometer) widths. Calculations presented for such channel waveguides show reductions in size by at least an order of magnitude are possible for directional couplers and other structures involving curved channel waveguide sections. Such size reductions would allow the realization of significantly higher levels of device integration than are now currently possible. 相似文献
18.
Optical channel waveguides of meta-nitroaniline (m-NA) crystal, which has potential applications to nonlinear optical devices, have been fabricated on glass substrates having fine grooves. The crystal growth was performed by zone-melting, scanning a CO2 laser beam along the grooves filled with the polycrystal m-NA. Optical and X-ray observations showed that zone-melting changed the polycrystalline state to a single crystalline state with the 〈001〉 direction along the groove. The scattering loss for a 5 mm-long m-NA crystal waveguide (100 μm both in width and in depth) was found to decrease from 50 dB to 2.5 dB with this process. 相似文献
19.
Feng Chen 《固体与材料科学评论》2008,33(3-4):165-182
Ion beam implantation has been used not only to modify some properties of the bulk materials but also to construct waveguide structures in many optical substrates by accurate control the refractive index in selected regions. This paper reviews the recent development of ion beam implantations on fabrication of two-dimensional (2D) optical waveguides, i.e., in cases of channel or ridge configurations, in diverse insulating optical materials by giving detailed fabrication methods and research progress obtained to date. Future prospects of practical applications in photonics are also discussed briefly. Another aim of this work is to show the challenging task of this field, that is, to create practical 2D waveguide devices applicable in any existing insulating optical materials. 相似文献
20.
In the present work the fabrication of high-quality LiNbO3 waveguides, based on Zn diffusion from vapor phase using a two-step diffusion process, has been demonstrated. The optical
waveguides fabricated using this method have low propagation losses (less than 0.5 dB/cm measured at 633 nm), as a consequence
of the high surface quality obtained. High photorefractive damage resistance is reported, and it has been related to the Zn
incorporation into the LiNbO3 crystals. Additional advantages of this waveguide fabrication method due to the low temperature of the process (<900 °C)
are to prevent Li out-diffusion and to preserve ferroelectric domain structures.
Received: 2 March 2000 / Accepted: 21 June 2000 / Published online: 13 September 2000 相似文献