APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

10 Oct 2005

Volume 87, Issue 15, Articles (15xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 87, 151103 (2005); http://dx.doi.org/10.1063/1.2089157 (3 pages)

Andrew B. Greytak, Carl J. Barrelet, Yat Li, and Charles M. Lieber
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Holographic scattering in photopolymer-dispersed liquid crystals

M. A. Ellabban, M. Fally, H. Uršič, and I. Drevenšek-Olenik

Appl. Phys. Lett. 87, 151101 (2005); http://dx.doi.org/10.1063/1.2089148 (3 pages) | Cited 12 times

Online Publication Date: 3 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Strong polarization-conserving holographic scattering was observed in a photopolymer-dispersed liquid crystal film fabricated from the UV curable mixture of commercially available constituents. During the photopolymerization process a bright corona of diffracted light evolves around the pump beam. The intensity of the rotationally symmetric light distribution increases upon exposure. By rotating the sample, two characteristic diffraction rings appear which can be explained by the Ewald sphere construction. Our results demonstrate that the associated parasitic holograms are very pronounced. Hence, their presence must be accounted for whenever preparing and utilizing holographic polymer-dispersed liquid crystals in any application.
Show PACS
42.70.Ln Holographic recording materials; optical storage media
42.40.Eq Holographic optical elements; holographic gratings
42.70.Jk Polymers and organics
42.70.Df Liquid crystals
61.30.Pq Microconfined liquid crystals: droplets, cylinders, randomly confined liquid crystals, polymer dispersed liquid crystals, and porous systems
68.15.+e Liquid thin films

Longitudinal-mode competition induced instabilities of Cr4+,Nd3+:Y3Al5O12 self-Q-switched two-mode laser

Jun Dong and Ken-ichi Ueda

Appl. Phys. Lett. 87, 151102 (2005); http://dx.doi.org/10.1063/1.2089153 (3 pages) | Cited 10 times

Online Publication Date: 3 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Stable single-longitudinal-mode laser pulses and instability of two-longitudinal-mode oscillation due to the spatial hole-burning effect were observed experimentally in a laser-diode pumped microchip Cr4+,Nd3+:Y3Al5O12 self-Q-switched laser. We modified the multimode rate equations by including the spatial hole-burning effect in the active medium and the nonlinear absorption of the saturable absorber. The numerical simulations of the mode-competition dynamics of two-mode laser are in good agreement with the experimental data. Instability induced by the mode-competition dynamics was investigated by the evolution of the inversion population and the bleaching and recovery of the inversion population of the saturable absorber.
Show PACS
42.55.Rz Doped-insulator lasers and other solid state lasers
42.55.Sa Microcavity and microdisk lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Px Semiconductor lasers; laser diodes
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Semiconductor nanowire laser and nanowire waveguide electro-optic modulators

Andrew B. Greytak, Carl J. Barrelet, Yat Li, and Charles M. Lieber

Appl. Phys. Lett. 87, 151103 (2005); http://dx.doi.org/10.1063/1.2089157 (3 pages) | Cited 90 times

Online Publication Date: 3 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electric field modulation of visible and ultraviolet nanoscale lasers consisting of single CdS or GaN nanowires has been achieved using integrated, microfabricated electrodes. Modulation of laser emission intensity is achieved with no detectable change in the laser wavelength. The devices can also be operated below the lasing threshold to modulate the intensity of light propagating within the nanowire waveguide. Studies of the electric field dependence in devices of varied geometry indicate that modulation is due to an electroabsorption mechanism. These findings expand opportunities for multicolor, nanowire-based photonic devices and circuits.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Fc Modulation, tuning, and mode locking
42.79.Gn Optical waveguides and couplers
42.79.Hp Optical processors, correlators, and modulators
42.82.-m Integrated optics

Repeatable nanostructures in dielectrics by femtosecond laser pulse trains

Lan Jiang and Hai-Lung Tsai

Appl. Phys. Lett. 87, 151104 (2005); http://dx.doi.org/10.1063/1.2093935 (3 pages) | Cited 15 times

Online Publication Date: 3 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using the plasma model recent developed by the authors, this study predicts the existence of a constant ablation-depth zone with respect to fluence in femtosecond laser ablation of dielectrics, which has also been observed experimentally. It is found that the value of the constant ablation depth is significantly decreased by the pulse train technology. Repeatable nanostructures can be achieved with the parameters in the constant ablation-depth zone of a femtosecond pulse train, even when the laser system is subject to fluctuations in fluences.
Show PACS
42.62.-b Laser applications
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Near-field optical recording using a planar solid immersion mirror

Chubing Peng, Christophe Mihalcea, Dorothea Büchel, William A. Challener, and Edward C. Gage

Appl. Phys. Lett. 87, 151105 (2005); http://dx.doi.org/10.1063/1.2093937 (3 pages) | Cited 9 times

Online Publication Date: 3 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A near-field planar solid immersion mirror (PSIM) has been developed and applied to the writing and reading of marks in a phase-change material. Light focusing of a PSIM is realized by a two-dimensional parabolic reflective surface integrated in a planar waveguide. Using a PSIM fabricated out of a waveguide consisting of a 100 nm Ta2O5 core layer and a SiO2 cladding layer on an Al2O3–TiC substrate, we have recorded marks with dimensions of λ/4.
Show PACS
42.79.Vb Optical storage systems, optical disks
42.79.Bh Lenses, prisms and mirrors
42.82.Et Waveguides, couplers, and arrays
42.79.Gn Optical waveguides and couplers

Surface laser emission from solid polymer dye in a guided mode resonant grating filter structure

Takashi Kobayashi, Yoshiaki Kanamori, and Kazuhiro Hane

Appl. Phys. Lett. 87, 151106 (2005); http://dx.doi.org/10.1063/1.2081116 (2 pages) | Cited 28 times

Online Publication Date: 3 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter describes the design, fabrication, and experimental results of a micro solid polymer dye laser designed on the basis of a guided mode resonant grating (GMRG). The resonant condition of GMRG includes the second-order resonance of the distributed feedback cavity. A surface laser emission was obtained in a patterned region by the pulsed-laser pumping. The grating was fabricated by the electron beam lithography and the fast atom beam etching. Dye (rhodamine 6G)-doped poly(methylmethacrylate) was spin-coated on the grating. The laser oscillation occurred in the direction vertical to the grating plane with a sharp peak (Q-value ∼ 1271) in a single mode designed by the GMRG analysis.
Show PACS
42.60.By Design of specific laser systems
42.55.Mv Dye lasers
42.55.Rz Doped-insulator lasers and other solid state lasers
42.86.+b Optical workshop techniques
42.79.Dj Gratings
42.79.Ci Filters, zone plates, and polarizers

Postfabrication fine-tuning of photonic crystal microcavities in InAs/InP quantum dot membranes

Dan Dalacu, Simon Frédérick, Philip J. Poole, Geof C. Aers, and Robin L. Williams

Appl. Phys. Lett. 87, 151107 (2005); http://dx.doi.org/10.1063/1.2099516 (3 pages) | Cited 19 times

Online Publication Date: 4 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A method to fine-tune photonic crystal defect cavities is developed based on successive oxidation and wet etching cycles. Photonic crystal microcavities based on InP membranes are oxidized using an ultraviolet (UV)/ozone treatment, and the oxide is subsequently removed using a hydrofluoric acid solution. Each oxidation/etch cycle consumes a thin layer of InP directly exposed to the UV/ozone, enlarging the radius of holes in the photonic crystal and decreasing the membrane thickness. The method is applied to single missing air-hole defect cavities with embedded InAs quantum dots, permitting measurement of the resonant frequency tuning in emission. Defect mode energies were found to blueshift 1.74 meV per cycle, consistent with finite-difference time-domain simulations. A tuning range of 33 meV was obtained after 20 cycles.
Show PACS
42.70.Qs Photonic bandgap materials
81.65.Mq Oxidation
78.67.Hc Quantum dots
81.65.Cf Surface cleaning, etching, patterning
81.05.Ea III-V semiconductors

Subwavelength microwave resonators exhibiting strong coupling to radiation modes

Howard R. Stuart and Cuong Tran

Appl. Phys. Lett. 87, 151108 (2005); http://dx.doi.org/10.1063/1.2099524 (3 pages) | Cited 6 times

Online Publication Date: 4 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate a subwavelength spherical resonator at microwave frequencies designed to mimic the electromagnetic behavior of a negative permittivity sphere. The structure, which has a radius of ∼ λ/12 (where λ is the resonant wavelength), consists of an axially symmetric array of noninterconnected conducting elements forming a resonant spherical object. The structure exhibits many of the properties inherent to negative permittivity spherical resonators, the most notable being a very strong coupling to radiation modes despite being much smaller than the wavelength. This characteristic is quantified by the radiation Q-factor, which was observed to be near 1.5 times the theoretical limit in some of the measured samples, matching the performance achievable in a negative permittivity sphere of comparable electrical size. These resonators may find application in the design of electrically small antennas, as well as in the experimental “simulation,” at microwave frequencies, of nanophotonic device concepts based upon localized plasmon resonances in metal nanoparticles.
Show PACS
84.40.Az Waveguides, transmission lines, striplines

High-temperature and low-threshold midinfrared interband cascade lasers

Rui Q. Yang, Cory J. Hill, and B. H. Yang

Appl. Phys. Lett. 87, 151109 (2005); http://dx.doi.org/10.1063/1.2103387 (3 pages) | Cited 28 times

Online Publication Date: 4 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A broad-area midinfrared interband cascade (IC) laser has been demonstrated with a threshold current as low as ∼ 630 A/cm2 at 300 K. Despite exhibiting a large specific thermal resistance ( ∼ 56 K cm2/kW at 172 K), the device delivered cw power near 200 mW/facet at 500 mA and at 83 K and lased in cw mode up to 172 K. A 0.5-mm-long laser delivered cw power of ∼ 253 mW/facet at 400 mA and at 82 K, and had power efficiency as high as 26% at ∼ 80 K. Narrow mesa stripe IC lasers had relatively higher threshold current density, yet lased at temperatures up to 237 and 350 K in cw and pulsed modes, respectively. The feasibility of cw operation at higher temperatures and directions for improving IC laser performance are discussed based on the experimental data.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

High-efficiency laser-diodes-pumped microthickness Yb:Y3Al5O12 slab laser

K. Sueda, H. Takahashi, S. Kawato, and T. Kobayashi

Appl. Phys. Lett. 87, 151110 (2005); http://dx.doi.org/10.1063/1.2103395 (3 pages) | Cited 3 times

Online Publication Date: 4 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A high-efficiency and high-power Yb:Y3Al5O12 oscillator was developed based on the microthickness slab structure with high aspect ratio to obtain one-dimensional temperature gradient and to reduce the temperature increase in the crystal. Laser output power of 257 W was obtained in cw oscillation with 42% optical conversion efficiency at a pump power of 608 W.
Show PACS
42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems

Nonlinear diffraction and second-harmonic generation enhancement in silicon-opal photonic crystals

A. A. Fedyanin, O. A. Aktsipetrov, D. A. Kurdyukov, V. G. Golubev, and M. Inoue

Appl. Phys. Lett. 87, 151111 (2005); http://dx.doi.org/10.1063/1.2077836 (3 pages) | Cited 15 times

Online Publication Date: 4 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nonlinear diffraction in three-dimensional silicon-filled photonic crystals of opals is studied. Efficient backward second-harmonic generation (SHG) is observed in the specular direction upon the fundamental radiation reflection from the (111) face of the face-centered-cubic opal lattice. Tuning the fundamental wavelength across the photonic band gap (PBG) results in the 20-times increase of the second-harmonic intensity. The SHG peak has the width of approximately 20 nm and is located at the long-wavelength edge of the PBG.
Show PACS
42.70.Qs Photonic bandgap materials
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

All-optical switches on a silicon chip realized using photonic crystal nanocavities

Takasumi Tanabe, Masaya Notomi, Satoshi Mitsugi, Akihiko Shinya, and Eiichi Kuramochi

Appl. Phys. Lett. 87, 151112 (2005); http://dx.doi.org/10.1063/1.2089185 (3 pages) | Cited 65 times

Online Publication Date: 5 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate all-optical switching in the telecommunication band, in silicon photonic crystals at high speed ( ∼ 50 ps), with extremely low switching energy (a few 100 fJ), and high switching contrast ( ∼ 10 dB). The devices consist of ultrasmall high-quality factor nanocavities connected to input and output waveguides. Switching is induced by a nonlinear refractive-index change caused by the plasma effect of carriers generated by two-photon absorption in silicon. The high-quality factor and small mode volume led to an extraordinarily large reduction in switching energy. The estimated internal switching energy in the nanocavity is as small as a few tens of fJ, indicating that further reduction on the operating energy is possible.
Show PACS
42.65.Pc Optical bistability, multistability, and switching, including local field effects
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.70.Qs Photonic bandgap materials
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.79.Gn Optical waveguides and couplers
42.82.Gw Other integrated-optical elements and systems

On the performance and surface passivation of type II InAs/GaSb superlattice photodiodes for the very-long-wavelength infrared

Andrew Hood, Manijeh Razeghi, Edward H. Aifer, and Gail J. Brown

Appl. Phys. Lett. 87, 151113 (2005); http://dx.doi.org/10.1063/1.2089170 (3 pages) | Cited 22 times

Online Publication Date: 5 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate very-long-wavelength infrared type II InAs/GaSb superlattice photodiodes with a cutoff wavelength (λc,50%) of 17 μm. We observed a zero-bias, peak Johnson noise-limited detectivity of 7.63×109 cm Hz1/2/W at 77 K with a 90%–10% cutoff width of 17 meV, and quantum efficiency of 30%. Variable area diode zero-bias resistance-area product (R0A) measurements indicated that silicon dioxide passivation increased surface resistivity by nearly a factor of 5, over unpassivated photodiodes, and increased overall R0A uniformity. The bulk R0A at 77 K was found to be 0.08 Ω cm2, with RA increasing more than twofold at 25 mV reverse bias.
Show PACS
85.60.Dw Photodiodes; phototransistors; photoresistors
81.65.Rv Passivation
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
81.05.Ea III-V semiconductors

Photonic-crystal-fiber pigtail device integrated with lens-duct optics for terahertz radiation coupling

Gilbert Diwa, Alex Quema, Elmer Estacio, Romeric Pobre, Hidetoshi Murakami, Shingo Ono, and Nobuhiko Sarukura

Appl. Phys. Lett. 87, 151114 (2005); http://dx.doi.org/10.1063/1.2093941 (3 pages) | Cited 12 times

Online Publication Date: 7 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An integrated optics called terahertz (THz) pigtail, which is comprised of an emitter, an optically transparent launching media, and a waveguide, is devised and fabricated. The InAs emitter under a 1 T magnetic field is coupled to the launching media using silicone grease, an index matching liquid. The launching media, a lens duct made from a polymer based on poly 4-methyl pentene-1 (commonly known as TPX), is designed based on the concept of guiding THz radiation into Teflon photonic crystal fiber (PCF) waveguide by means of total internal reflection. It is found that the constructed THz lens duct is able to channel and couple the THz radiation into the PCF waveguide with a loss of <1 dB. The results here show that the idea of using the THz pigtail can be a potential means of effectively directing THz radiation.
Show PACS
84.40.−x
42.82.Et Waveguides, couplers, and arrays
42.82.−m

Rectification and intrinsic photocurrent of GaAs/Si photodiodes formed with pulsed-laser deposition at 1064 nm

B. Ullrich and A. Erlacher

Appl. Phys. Lett. 87, 151115 (2005); http://dx.doi.org/10.1063/1.2093942 (3 pages) | Cited 6 times

Online Publication Date: 7 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
With a rate of 1 nm per minute, thin-film p-GaAs has been deposited on n-Si with nanosecond laser pulses at 1064 nm. The samples revealed rectification with an uncommon power dependence on the forward bias. Furthermore, we noticed that the intrinsic photocurrent spectra sensitively depend on the deposition time. Increasing this duration from one to three hours shifts the maximum of the spectral device response from GaAs to Si. The result stresses the flexibility of pulsed-laser deposition to alter device properties in extremely simple ways.
Show PACS
85.60.Dw Photodiodes; phototransistors; photoresistors
81.15.Fg Pulsed laser ablation deposition
73.40.Ei Rectification

Metallic tip probe providing high intensity and small spot size with a small background light in near-field optics

Kazuo Tanaka, Masahiro Tanaka, and Tatsuhiko Sugiyama

Appl. Phys. Lett. 87, 151116 (2005); http://dx.doi.org/10.1063/1.2093928 (3 pages) | Cited 7 times

Online Publication Date: 7 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A metallic tip probe that gives high optical intensity and small spot size with a small background light is proposed and simulated. The proposed tip probe provides advantages of both the aperture probe and the apertureless probe currently used in the scanning near-field optical microscope. The tip probe is illuminated by surface plasmon polaritons transmitted through the I-shaped aperture in a pyramidal structure on a thick metallic screen. Scattering of optical waves by this structure is solved numerically using a volume integral equation by generalized conjugate residual iteration and fast Fourier transformation. The proposed tip probe is shown to simultaneously provide both high near-field intensity and small spot size with a small background light.
Show PACS
07.79.Fc Near-field scanning optical microscopes
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)

Enhancement of solar cell performance by employing planar spectral converters

W. G. J. H. M. van Sark

Appl. Phys. Lett. 87, 151117 (2005); http://dx.doi.org/10.1063/1.2099532 (3 pages) | Cited 16 times

Online Publication Date: 7 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect on solar cell performance of planar converters containing quantum dots (QDs) as wavelength-shifting entities on top of multicrystalline silicon cells was investigated by means of model studies with varying incident spectra. These included global, direct, and diffuse spectra with Air Mass (AM) values ranging from 1 to 10. In case of AM1.5, a planar converter with QDs emitting at 603 nm yields a short-circuit current increase of 6.3%, 9.6%, and 28.6% for direct, global, and diffuse irradiation, respectively, as a result of the larger blue/green content of diffuse spectra with respect to direct and global ones. For other AM values, similar results are calculated, with a lower increase toward high AM values.
Show PACS
84.60.Jt Photoelectric conversion
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Ultra-high-Q microcavity operation in H2O and D2O

A. M. Armani, D. K. Armani, B. Min, K. J. Vahala, and S. M. Spillane

Appl. Phys. Lett. 87, 151118 (2005); http://dx.doi.org/10.1063/1.2099529 (3 pages) | Cited 21 times

Online Publication Date: 7 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Optical microcavities provide a possible method for boosting the detection sensitivity of biomolecules. Silica-based microcavities are important because they are readily functionalized, which enables unlabeled detection. While silica resonators have been characterized in air, nearly all molecular detections are performed in solution. Therefore, it is important to determine their performance limits in an aqueous environment. In this letter, planar microtoroid resonators are used to measure the relationship between quality factor and toroid diameter at wavelengths ranging from visible to near-IR in both H2O and D2O, and results are then compared to predictions of a numerical model. Quality factors (Q) in excess of 108, a factor of 100 higher than previous measurements in an aqueous environment, are observed in both H2O and D2O.
Show PACS
42.79.-e Optical elements, devices, and systems
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing

Enhanced light emission from an organic photonic crystal with a nanocavity

M. Kitamura, S. Iwamoto, and Y. Arakawa

Appl. Phys. Lett. 87, 151119 (2005); http://dx.doi.org/10.1063/1.2103404 (3 pages) | Cited 18 times

Online Publication Date: 7 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An organic photonic crystal (PC) with a nanocavity has been fabricated on a SiO2 membrane with air holes. The emission peak caused by the resonant mode of the nanocavity was clearly observed from the nanocavity area of the PC. The emission peak corresponded to degenerated dipole modes from comparison between measured and calculated results. Modification of a nanocavity caused the peak splitting of dipole modes and the appearance of a peak corresponding to a hexapole mode. The emission peak with a quality factor of about 1000 was obtained from a PC with a modified nanocavity.
Show PACS
42.70.Qs Photonic bandgap materials

Subpicosecond luminescence spectroscopy of exciton localization in InxGa1−xN films

Yoshihiko Kanemitsu, Koichi Tomita, and Hideyuki Inouye

Appl. Phys. Lett. 87, 151120 (2005); http://dx.doi.org/10.1063/1.2103407 (3 pages) | Cited 5 times

Online Publication Date: 7 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have studied the exciton localization dynamics in InxGa1−xN epitaxial films with different In compositions (x = 0.02, 0.05, and 0.09) by means of optical Kerr-gate time-resolved photoluminescence (PL) spectral measurements. By changing excitation wavelength of 150 fs laser pulses, InxGa1−xN films are resonantly excited around their exciton energies at 6 K. Under the resonant excitation, the PL dynamics is sensitive to the In composition of the sample and the excitation laser intensity. In the low In composition samples, the formation time of radiative excitons at localized states is 5–10 ps. In the high In composition samples, the gradual redshift of the PL peak energy is observed within several tens of picoseconds. The radiative recombination processes of excitons are discussed.
Show PACS
78.55.Cr III-V semiconductors
78.47.-p Spectroscopy of solid state dynamics
78.66.Fd III-V semiconductors
71.35.-y Excitons and related phenomena

Enhanced feedback in organic photonic-crystal lasers

Rik Harbers, Patric Strasser, Daniele Caimi, Rainer F. Mahrt, Nikolaj Moll, Bert Jan Offrein, Daniel Erni, Werner Bächtold, and Ullrich Scherf

Appl. Phys. Lett. 87, 151121 (2005); http://dx.doi.org/10.1063/1.2103396 (3 pages) | Cited 11 times

Online Publication Date: 7 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The mode coupling of organic lasers is greatly enhanced by a photonic crystal that consists of a thin layer of titanium dioxide (TiO2) with a rectangular lattice of holes. The use of TiO2 increases the index contrast in the photonic crystal as well as the confinement in the waveguide, which results in larger feedback given to the lasing modes. This in turn leads to lower thresholds and much smaller devices. Vertically emitting laser devices have been fabricated according to optimized parameters, and the spectral features measured are in excellent agreement with simulations. The devices feature a three to five times lower threshold than devices whose feedback structure is etched directly into the fused silica substrate.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.70.Qs Photonic bandgap materials
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Tunable optical fiber filters with magnetic fluids

Weijun Liao, Xianfeng Chen, Yuping Chen, Shengli Pu, Yuxing Xia, and Qu Li

Appl. Phys. Lett. 87, 151122 (2005); http://dx.doi.org/10.1063/1.2103401 (3 pages) | Cited 10 times

Online Publication Date: 7 October 2005

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter presents a tunable optical fiber filter based on a long-period grating (LPG) by applying a magnetic field on a magnetic nanoparticle fluid. The movement of the magnetic fluid jacket surrounding the fiber cladding controlled by an applied magnetic field results in a variation of the external index between that of the magnetic fluid and air. As a result, the attenuation band of the LPG is shifted. The observed center wavelength shift of the attenuation band is as large as 7 nm, which can cover eight dense wavelength division multiplexing channels (100 GHz channel spacing). Repeatable transport of a magnetic fluid at a switching rate of 1 Hz is demonstrated.
Show PACS
42.81.Wg Other fiber-optical devices
42.79.Ci Filters, zone plates, and polarizers
42.79.Dj Gratings
75.50.Mm Magnetic liquids
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close