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

6 Aug 2001

Volume 79, Issue 6, pp. 705-888

Return to All Sections
back to top
RSS Feeds

Picosecond superconducting single-photon optical detector

G. N. Gol’tsman, O. Okunev, G. Chulkova, A. Lipatov, A. Semenov, K. Smirnov, B. Voronov, A. Dzardanov, C. Williams, and Roman Sobolewski

Appl. Phys. Lett. 79, 705 (2001); http://dx.doi.org/10.1063/1.1388868 (3 pages) | Cited 250 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We experimentally demonstrate a supercurrent-assisted, hotspot-formation mechanism for ultrafast detection and counting of visible and infrared photons. A photon-induced hotspot leads to a temporary formation of a resistive barrier across the superconducting sensor strip and results in an easily measurable voltage pulse. Subsequent hotspot healing in ∼30 ps time frame, restores the superconductivity (zero-voltage state), and the detector is ready to register another photon. Our device consists of an ultrathin, very narrow NbN strip, maintained at 4.2 K and current-biased close to the critical current. It exhibits an experimentally measured quantum efficiency of ∼20% for 0.81 μm wavelength photons and negligible dark counts. © 2001 American Institute of Physics.
Show PACS
85.25.Oj Superconducting optical, X-ray, and γ-ray detectors (SIS, NIS, transition edge)
85.60.Gz Photodetectors (including infrared and CCD detectors)
85.25.Pb Superconducting infrared, submillimeter and millimeter wave detectors
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
74.78.-w Superconducting films and low-dimensional structures
06.60.Jn High-speed techniques (microsecond to femtosecond)
74.25.Gz Optical properties

Absorption bleaching of squarylium dye J aggregates via a two-photon excitation process

Makoto Furuki, Minquan Tian, Yasuhiro Sato, Lyong Sun Pu, Satoshi Tatsuura, and Shuji Abe

Appl. Phys. Lett. 79, 708 (2001); http://dx.doi.org/10.1063/1.1390322 (3 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Squarylium dye J aggregates exhibit ultrafast nonlinear optical response of absorption saturation at the resonant wavelength of 770 nm. We studied the two-photon excitation process of J aggregates. By fluorescence measurement, we found the two-photon absorption band at 1.3 μm, which was different from that of the dye solution at 1.2 μm. Absorption saturation at 770 nm via a two-photon excitation process was observed by two-photon resonant excitation at 1.3 μm and also by off-resonant excitation at 1.55 μm, suggesting the possibility of J aggregates for optical switching materials working at the wavelength used in optical communications. © 2001 American Institute of Physics.
Show PACS
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
42.70.Jk Polymers and organics
42.65.Pc Optical bistability, multistability, and switching, including local field effects
78.55.Bq Liquids
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Efficient and high-power AlGaN-based ultraviolet light-emitting diode grown on bulk GaN

Toshio Nishida, Hisao Saito, and Naoki Kobayashi

Appl. Phys. Lett. 79, 711 (2001); http://dx.doi.org/10.1063/1.1390485 (2 pages) | Cited 117 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
By introducing thick bulk GaN as a substrate, we improved the performance of an AlGaN-based ultraviolet (UV) light-emitting diode (LED). The output power exceeds 3 mW at the injection current of 100 mA under a bare-chip geometry. Internal quantum efficiency is estimated as more than 80%, and the peak wavelength is 352 nm. The maximum power exceeds 10 mW at a large current injection of 400 mA, with an operation voltage of less than 6 V. These results indicate that an efficient UV LED is intrinsically possible by the combination of appropriate device design and the nitride substrate. By introducing packaging technology to enhance extraction efficiency, we will have a compact and efficient UV light source in the wide wavelength range of 200–360 nm, similar to conventional longer-wavelength LEDs. © 2001 American Institute of Physics.
Show PACS
85.60.Jb Light-emitting devices
78.66.Fd III-V semiconductors

Mechanism of terahertz lasing in SiGe/Si quantum wells

A. Blom, M. A. Odnoblyudov, H. H. Cheng, I. N. Yassievich, and K. A. Chao

Appl. Phys. Lett. 79, 713 (2001); http://dx.doi.org/10.1063/1.1389769 (3 pages) | Cited 15 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Intense terahertz (THz) stimulated emission from boron-doped SiGe/Si quantum well structures with internal strain has been observed recently. We present a theoretical calculation which shows the formation of resonant states, and explains the origin of the observed temperature dependence of the dc conductivity under low bias voltage. Thus, the mechanism of THz lasing is population inversion of the resonant state with respect to the localized impurity states. This is the same mechanism of lasing as in uniaxially stressed p-Ge THz lasers. © 2001 American Institute of Physics.
Show PACS
78.67.De Quantum wells
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
42.55.Px Semiconductor lasers; laser diodes
78.45.+h Stimulated emission
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.61.Le Other inorganic semiconductors
73.61.Cw Elemental semiconductors

Highly efficient mirrorless laser-like emission in an organic molecular salt

Achintya K. Bhowmik, Aditya Dharmadhikari, and Mrinal Thakur

Appl. Phys. Lett. 79, 716 (2001); http://dx.doi.org/10.1063/1.1388870 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Unusually high conversion efficiency in laser-like emission has been observed in solutions of an organic molecular salt, styrylpyridinium cyanine dye, at a low threshold input pulse energy. Pumped with frequency-doubled 55 ps pulses from a Nd:YAG laser, a conversion efficiency as high as 40% was achieved without incorporating external mirrors. The spectrally narrowed output beam was observed to be polarized and having a low divergence. The exceptionally low threshold (<1 μJ with excitation area ∼5 mm2) and high conversion efficiency at a high molar concentration in spite of a very small photoluminescence quantum efficiency (<0.3%) can be attributed to the large dipole moments associated with the charge-transfer transitions of these molecules favoring strong cooperative emission. © 2001 American Institute of Physics.
Show PACS
42.70.Hj Laser materials
42.55.Mv Dye lasers
78.55.Bq Liquids
42.70.Jk Polymers and organics

Optimum Er concentration for in situ doped GaN visible and infrared luminescence

D. S. Lee, J. Heikenfeld, A. J. Steckl, U. Hommerich, J. T. Seo, A. Braud, and J. Zavada

Appl. Phys. Lett. 79, 719 (2001); http://dx.doi.org/10.1063/1.1390480 (3 pages) | Cited 19 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
GaN thin films have been doped with varying Er concentrations (0.01–10 at. %) during molecular-beam-epitaxy growth. As expected, the visible and infrared (IR) emissions, from photoluminescence (PL) and electroluminescence (EL), are a strong function of Er concentration. We report on the determination of an optimum Er doping level for PL and EL intensity. Secondary ion mass spectroscopy and Rutherford backscattering measurements showed that the Er concentration in GaN increased exponentially with Er cell temperature. PL and EL intensity of green emission at 537 and 558 nm, due to Er 4f–4f inner shell transitions, exhibited a maximum at ∼1 at. % Er. IR PL intensity at 1.54 μm, due to another Er transition, revealed the same maximum for ∼1 at. % Er concentration. PL lifetime measurements at 537 nm showed that samples with Er concentration <1 at. % had a lifetime of ∼5 μs. For Er concentration ⩾1 at. %, the lifetime decreased rapidly to values below 1 μs. This concentration quenching is believed to be due to a combination of Er cross relaxation and energy transfer to GaN defects, eventually followed by precipitation. This conclusion is supported by x-ray diffraction measurements. As a result, we have determined that the optimum Er doping concentration into GaN is ∼1 at. %. © 2001 American Institute of Physics.
Show PACS
78.55.Cr III-V semiconductors
78.60.Fi Electroluminescence
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
61.72.S- Impurities in crystals
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
64.75.-g Phase equilibria
81.30.Mh Solid-phase precipitation

Temperature-dependent measurement of Auger recombination in self-organized In0.4Ga0.6As/GaAs quantum dots

S. Ghosh, P. Bhattacharya, E. Stoner, J. Singh, H. Jiang, S. Nuttinck, and J. Laskar

Appl. Phys. Lett. 79, 722 (2001); http://dx.doi.org/10.1063/1.1391401 (3 pages) | Cited 31 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report experimental studies of temperature-dependent Auger recombination coefficients in self-assembled quantum dots. The results are based on a study of temperature-dependent large signal modulation experiments made on self-organized In0.4Ga0.6As/GaAs quantum dot lasers. The Auger coefficient decreases from ∼ 8×10−29 cm6/s at 100 K to ∼ 4×10−29 cm6/s at 300 K. This behavior, which is different from results in other higher-dimensional systems, is explained in terms of the temperature dependence of electron-hole scattering in the dots and contribution from higher lying states in the dot and adjoining layers. © 2001 American Institute of Physics.
Show PACS
73.63.Kv Quantum dots
73.21.La Quantum dots
42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Femtosecond laser interference technique with diffractive beam splitter for fabrication of three-dimensional photonic crystals

Toshiaki Kondo, Shigeki Matsuo, Saulius Juodkazis, and Hiroaki Misawa

Appl. Phys. Lett. 79, 725 (2001); http://dx.doi.org/10.1063/1.1391232 (3 pages) | Cited 106 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A simple optical interference method to fabricate microperiodic structures was demonstrated. Femtosecond laser pulse was split by a diffractive beam splitter and overlapped with two lenses. Temporal overlap of the split femtosecond pulses, which requires 10 μm order accuracy in optical path lengths, was automatically achieved by this optical setup. One-, two-, and three-dimensional periodic microstructures with micrometer-order periods were fabricated using this method. © 2001 American Institute of Physics.
Show PACS
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.70.Qs Photonic bandgap materials
42.79.Fm Reflectors, beam splitters, and deflectors
42.25.Hz Interference
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Aperiodic optical superlattices engineered for optical frequency conversion

H. Liu, Y. Y. Zhu, S. N. Zhu, C. Zhang, and N. B. Ming

Appl. Phys. Lett. 79, 728 (2001); http://dx.doi.org/10.1063/1.1381569 (3 pages) | Cited 19 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An aperiodic optical superlattice is designed. The designing method is universal and can be applied to all frequency conversion processes by using the coupling of quasiphase matching, without any limitations to special materials and to given fundamental wavelengths. © 2001 American Institute of Physics.
Show PACS
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Wc Optical coatings
78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
42.15.Eq Optical system design

Emission in a SnS2 inverted opaline photonic crystal

S. G. Romanov, T. Maka, C. M. Sotomayor Torres, M. Müller, and R. Zentel

Appl. Phys. Lett. 79, 731 (2001); http://dx.doi.org/10.1063/1.1389825 (3 pages) | Cited 26 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The photoluminescence of a dye embedded in the three-dimensional SnS2 inverted opal has been studied. Changes of the emission spectrum compared with the free-space dye emission was observed in the stop-band frequency range in accord with reflectance/transmission spectra of this photonic crystal. The angular-dependent component, due to the Bragg stop band, and the angular-independent component, which is, possibly, related to the minimum in the density of photon states, have been distinguished in the dye emission spectrum. © 2001 American Institute of Physics.
Show PACS
78.55.-m Photoluminescence, properties and materials
42.70.Qs Photonic bandgap materials
78.40.-q Absorption and reflection spectra: visible and ultraviolet
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close