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19 Mar 2007

Volume 90, Issue 12, Articles (12xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 90, 123101 (2007); http://dx.doi.org/10.1063/1.2716242 (3 pages)

G. Z. Shen, Y. Bando, J. Q. Hu, and D. Golberg
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High-power operation of diode edge-pumped, composite all-ceramic Yb:Y3Al5O12 microchip laser

Masaki Tsunekane and Takunori Taira

Appl. Phys. Lett. 90, 121101 (2007); http://dx.doi.org/10.1063/1.2714099 (3 pages) | Cited 26 times

Online Publication Date: 19 March 2007

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A solid-state laser material of composite all-ceramic Yb:Y3Al5O12 is applied as a source of a high-power, diode edge-pumped microchip laser. 520 W quasi-continuous-wave and 414 W continuous-wave (cw) output powers were obtained from the 3.7-mm-diameter, Yb doped ceramic core with a 200 μm thickness. The cw output power densities of 3.9 kW/cm2 and 0.19 MW/cm3 in the core area and volume, respectively, are the highest for an active-mirror solid-state laser. The maximum thermal stress in the ceramic core is estimated to be 384 MPa at the noncooled surface and is twice the tensile strength of single-crystal Y3Al5O12.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.55.Xi Diode-pumped lasers
42.60.By Design of specific laser systems

Plasmonic excitation of organic double heterostructure solar cells

J. K. Mapel, M. Singh, M. A. Baldo, and K. Celebi

Appl. Phys. Lett. 90, 121102 (2007); http://dx.doi.org/10.1063/1.2714193 (3 pages) | Cited 28 times

Online Publication Date: 19 March 2007

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The authors demonstrate that thin film organic photovoltaic cells are efficient detectors of surface plasmon polaritons (SPPs). For λ = 532 nm radiation in a Kretschmann configuration, the external quantum efficiency in fullerene–copper phthalocyanine photovoltaic cells is doubled at resonance to 12%. In thin heterojunction organic photovoltaics, SPP detection relies on a substantial increase in absorption when the incoming radiation is coupled to guided SPPs rather than unguided photons. SPP scattering and nonradiative losses are negligible; however, optical modeling shows that cathode metal penetration into the neighboring organic semiconductor is a major source of loss for SPP or photonic excitation.
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84.60.Jt Photoelectric conversion
85.60.Gz Photodetectors (including infrared and CCD detectors)
85.30.De Semiconductor-device characterization, design, and modeling

Enhanced photoinduced birefringence in polymer-dye complexes: Hydrogen bonding makes a difference

Arri Priimagi, Matti Kaivola, Francisco J. Rodriguez, and Martti Kauranen

Appl. Phys. Lett. 90, 121103 (2007); http://dx.doi.org/10.1063/1.2714292 (3 pages) | Cited 13 times

Online Publication Date: 19 March 2007

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The authors demonstrate that photoinduced birefringence in azo-dye-doped polymers is strongly enhanced by hydrogen bonding between the guest molecules and the polymer host. The primary mechanism behind the enhancement is the possibility to use high dye doping levels compared to conventional guest-host systems because dye aggregation is restrained by hydrogen bonding. Moreover, hydrogen bonding reduces the mobility of the guest molecules in the polymer host leading to a larger fraction of the induced birefringence to be preserved after the excitation light has been turned off.
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78.20.Fm Birefringence
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
61.72.up Other materials

Polarized optical feedback from an extremely short external cavity for controlling and stabilizing the polarization of vertical cavity surface emitting lasers

Mikel Arizaleta Arteaga, Olivier Parriaux, Manuel López-Amo, Hugo Thienpont, and Krassimir Panajotov

Appl. Phys. Lett. 90, 121104 (2007); http://dx.doi.org/10.1063/1.2714301 (3 pages) | Cited 2 times

Online Publication Date: 19 March 2007

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The authors present experimental results showing that polarization selective optical feedback from an extremely short external cavity induces switching between the two fundamental transverse modes with orthogonal linear polarization of the otherwise (without optical feedback) polarization stable vertical cavity surface emitting laser. Moreover, when properly selecting the external cavity length within a subwavelength range the polarization state of the emitted light can be chosen in either of the two fundamental transverse modes and stabilized against injection current variations. The numerical results reported are in good agreement with experiments.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Predictions of thermoelastic stress in a broad-area semiconductor laser

B. P. Cox and W. R. Smith

Appl. Phys. Lett. 90, 121105 (2007); http://dx.doi.org/10.1063/1.2714330 (2 pages) | Cited 1 time

Online Publication Date: 19 March 2007

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The coupling of electrical, optical, and thermal effects in broad-area semiconductor lasers has been investigated using a multilateral mode mathematical model. Numerical solutions for the active layer temperature rise are input into the thermal source terms of elasticity equations, leading to the prediction of the thermoelastic stresses which occur in regions of high defect concentration. The magnitude of this prediction is compared with the size of other stresses reported elsewhere in experimental observations of the degraded facet of broad-area devices.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Short wavelength (λ = 2.13 μm) intersubband luminescence from GaN/AlN quantum wells at room temperature

L. Nevou, M. Tchernycheva, F. H. Julien, F. Guillot, and E. Monroy

Appl. Phys. Lett. 90, 121106 (2007); http://dx.doi.org/10.1063/1.2715001 (3 pages) | Cited 33 times

Online Publication Date: 19 March 2007

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The authors report the observation of room-temperature intersubband luminescence at λ = 2.13 μm from GaN/AlN quantum wells under optical pumping at λ = 0.98 μm. The quantum wells are designed to exhibit three bound states in the conduction band. The emission arises from the e3e2 intersubband transition. Photoluminescence excitation spectroscopy shows that the emission is only observed for p-polarized excitation at wavelengths corresponding to the e1e3 intersubband transition. The measured external quantum efficiency is 10 pW/W.
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78.67.De Quantum wells
78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
73.21.Fg Quantum wells

Observation of superluminal propagation at negative group velocity in C60 solution

Hao Wang, Yundong Zhang, Nan Wang, Wenlong Yan, He Tian, Wei Qiu, and Ping Yuan

Appl. Phys. Lett. 90, 121107 (2007); http://dx.doi.org/10.1063/1.2715035 (3 pages) | Cited 7 times

Online Publication Date: 19 March 2007

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The authors observed the superluminal propagation at negative group velocity in C60 toluene solution firstly. The theoretical analysis was made based on density matrix model of superluminal propagation. The simulation result was well consistent with experimental measurement. The largest time advancement of 3.58 ms was got at 5.6×10−4 mol/l of sample concentration; the corresponding group velocity is −0.28 m/s.
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42.25.Bs Wave propagation, transmission and absorption

Method to improve the quality of acousto-optic imaging using an ultrashort and focused ultrasound pulse

Cuncheng Weng

Appl. Phys. Lett. 90, 121108 (2007); http://dx.doi.org/10.1063/1.2713126 (3 pages) | Cited 2 times

Online Publication Date: 20 March 2007

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The letter shows that the optical scattering and the length of ultrasound-wave train are key factors affecting the quality of acousto-optic imaging. A method using an ultrashort and focused ultrasound pulse is provided. The method has the potential to improve the quality of acousto-optic imaging.
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43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography

Experimental investigation of the lattice and electronic temperatures in Ga0.47In0.53As/Al0.62Ga0.38As1−xSbx quantum-cascade lasers

Miriam S. Vitiello, Gaetano Scamarcio, Vincenzo Spagnolo, Antonia Lops, Quankui Yang, Christian Manz, and Joachim Wagner

Appl. Phys. Lett. 90, 121109 (2007); http://dx.doi.org/10.1063/1.2717018 (3 pages) | Cited 12 times

Online Publication Date: 20 March 2007

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The authors extracted the thermal resistance (RL = 9.6 K/W) and the electrical power dependence of the electronic temperature (Re = 12.5 K/W) of Ga0.47In0.53As/Al0.62Ga0.38As1−xSbx quantum-cascade lasers (QCLs) operating at 4.9 μm, in the lattice temperature range of 60–90 K. The low electron-lattice coupling constant α = 10.4 K cm2/kA can be related to the beneficial effect of the high conduction band offset, peculiar to the GaInAs/AlGaAsSb material system, on the electron leakage. The authors found an active region cross-plane thermal conductivity value k⊥ = 1.8±0.1 W/(K m), which is approximately three times larger than that measured in QCLs with GaInAs/AlInAs heterostructures.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Reflection properties of hybrid quarter-wavelength silicon microstructures

Giuseppe Barillaro, Valerio Annovazzi-Lodi, Mauro Benedetti, and Sabina Merlo

Appl. Phys. Lett. 90, 121110 (2007); http://dx.doi.org/10.1063/1.2714293 (3 pages) | Cited 9 times

Online Publication Date: 21 March 2007

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The authors present experimental and numerical results relative to the polarization-resolved spectral reflectivity of one-dimensional periodic microstructures, evaluated in the near-infrared region at non-normal incidence. The tested hybrid quarter-wavelength microstructures, fabricated by electrochemical deep etching of silicon, consist of arrays of silicon walls and air gaps, with 3 and 4 μm periods and aspect ratio of up to 100. A theoretical Monte Carlo analysis taking into account the presence of a Gaussian statistical distribution for the structure porosity has been carried out and the calculated wavelength dependence of the reflectivity at non-normal incidence has been confirmed by experimental data.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.35.+c Brillouin and Rayleigh scattering; other light scattering
61.43.Gt Powders, porous materials

Two-photon absorption in quantum dots based on a nonconjugated conductive polymer

Jitto Titus and M. Thakur

Appl. Phys. Lett. 90, 121111 (2007); http://dx.doi.org/10.1063/1.2714995 (3 pages) | Cited 3 times

Online Publication Date: 21 March 2007

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Two-photon absorption has been measured in a nano-optical material (quantum dots) based on the nonconjugated conductive polymer, iodine-doped poly(β-pinene). The measurement has been made using open-aperture z scan at 730–860 nm with 150 fs pulses. Exceptionally large two-photon absorption coefficient has been observed with a peak of magnitude ∼ 2.6 cm/MW that appeared at ∼ 1.53 eV which is close to half of the optical gap corresponding to the charge-transfer transition involving the isolated double bond. Saturation of absorption was observed at lower intensities and shorter wavelengths. The results have been attributed to the quantum dots (subnanometer size) formed upon doping.
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78.67.Hc Quantum dots
42.65.-k Nonlinear optics
78.47.-p Spectroscopy of solid state dynamics
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
73.21.La Quantum dots
42.70.Jk Polymers and organics

Time-to-space mapping in a gas medium for the temporal characterization of vacuum-ultraviolet pulses

S. Cunovic, N. Müller, R. Kalms, M. Krikunova, M. Wieland, M. Drescher, Th. Maltezopoulos, U. Frühling, H. Redlin, E. Plönjes-Palm, and J. Feldhaus

Appl. Phys. Lett. 90, 121112 (2007); http://dx.doi.org/10.1063/1.2714999 (3 pages) | Cited 11 times

Online Publication Date: 21 March 2007

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The authors introduce a method for cross correlating vacuum-ultraviolet with near-infrared femtosecond light pulses in a perpendicular geometry. Photoelectrons generated in an atomic gas by laser-assisted photoionization are used to create a two-dimensional image of the cross-correlation volume, thereby mapping time onto a space coordinate. Thus, information about pulse duration and relative timing between the pulses can be obtained without the need to scan an optical delay line. First tests using vacuum-ultraviolet pulses from the free-electron laser at the Deutsches Elektronen Synchrotron set an upper limit for their temporal jitter with respect to external optical laser pulses.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
07.85.-m X- and γ-ray instruments
42.60.Fc Modulation, tuning, and mode locking
32.80.Fb Photoionization of atoms and ions

Dynamics of a two-state quantum dot laser with saturable absorber

E. A. Viktorov, M. A. Cataluna, L. O’Faolain, T. F. Krauss, W. Sibbett, E. U. Rafailov, and Paul Mandel

Appl. Phys. Lett. 90, 121113 (2007); http://dx.doi.org/10.1063/1.2715023 (3 pages) | Cited 7 times

Online Publication Date: 21 March 2007

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The authors study the regime of self-pulsations in a two-state quantum dot laser with saturable absorber. Experiments demonstrate and theory explains the appearance of self-pulsations at low relaxation oscillation frequency. The system exhibits a period doubling sequence of bifurcations leading to chaos.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.65.Sf Dynamics of nonlinear optical systems; optical instabilities, optical chaos and complexity, and optical spatio-temporal dynamics

Nonresonant electrical injection of excitons in an InGaAs quantum well

D. Bajoni, A. Miard, A. Lemaître, S. Bouchoule, J. Bloch, and J. Tignon

Appl. Phys. Lett. 90, 121114 (2007); http://dx.doi.org/10.1063/1.2715043 (3 pages) | Cited 9 times

Online Publication Date: 21 March 2007

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The authors report on electroluminescence measurements combined with photoluminescence excitation spectroscopy on a single InGaAs quantum well placed in the intrinsic region of a p-i-n photodiode. They show that at low current density, the spectra are dominated by the spectrally narrow excitonic emission. Moreover when increasing carrier injection, they observe the progressive transition from excitons into free electron-hole pairs. This structure meets all criteria to be integrated in a semiconductor microcavity and the present demonstration of exciton electroluminescence is the first step toward the achievement of the strong coupling regime under electrical injection.
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73.21.Fg Quantum wells
71.35.-y Excitons and related phenomena
78.55.Cr III-V semiconductors
78.60.Fi Electroluminescence
78.67.De Quantum wells
85.30.Kk Junction diodes

Optical properties of dilute nitrogen GaInNAs quantum dots

Stanko Tomić

Appl. Phys. Lett. 90, 121115 (2007); http://dx.doi.org/10.1063/1.2715096 (3 pages) | Cited 2 times

Online Publication Date: 21 March 2007

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The authors present a theoretical study of the ground state optical transition matrix element in quantum dots (QDs) with a dilute amount of nitrogen. They have investigated the interplay between the nitrogen to the conduction band mixing and piezoelectric field on the optical matrix element. With a reduced amount of indium and an increased amount of nitrogen in the QD, the optical matrix element becomes on the average larger and less sensitive to the variation of both the QD shape and size than is the case of an InNAs QD. The optical characteristics at room temperature and 1.5 μm wavelength are discussed.
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78.67.Hc Quantum dots
71.20.Nr Semiconductor compounds
73.21.La Quantum dots
77.65.-j Piezoelectricity and electromechanical effects
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.

Identification of modes and single mode operation of sapphire-bonded photonic crystal lasers under continuous-wave room temperature operation

M. H. Shih, Mahmood Bagheri, Adam Mock, S. J. Choi, J. D. O’Brien, P. D. Dapkus, and Wan Kuang

Appl. Phys. Lett. 90, 121116 (2007); http://dx.doi.org/10.1063/1.2715107 (3 pages) | Cited 6 times

Online Publication Date: 21 March 2007

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Sapphire-bonded photonic crystal laser cavities were fabricated and characterized under room temperature continuous-wave operation, and the single mode lasing with a side-mode-suppression ratio of 28 dB was observed. The lasing modes of the photonic crystal cavities were characterized and compared to calculated spectra from the three-dimensional finite-difference time-domain method.
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42.55.Tv Photonic crystal lasers and coherent effects
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Correlation between electron and negative O− ion emission during reactive sputtering of oxides

S. Mahieu and D. Depla

Appl. Phys. Lett. 90, 121117 (2007); http://dx.doi.org/10.1063/1.2715113 (2 pages) | Cited 17 times

Online Publication Date: 21 March 2007

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The energy distribution of negative O− ions has been measured during the reactive magnetron sputtering of 13 different target materials by the means of energy resolved mass spectrometry. For the same series of target materials the ion-induced secondary electron emission coefficient was determined in an earlier published research. A correlation between this ion-induced secondary electron emission coefficient and the emission of the high energetic negative O− ions was observed. This correlation should be taken into consideration in the selection of oxides for their high electron emission coefficients as these materials will emit at the same time negative O− ions.
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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Fabrication and device characteristics of Schottky-type bulk GaN-based “visible-blind” ultraviolet photodetectors

Yi Zhou, Claude Ahyi, Chin-Che Tin, John Williams, Minseo Park, Dong-Joo Kim, An-Jen Cheng, Dake Wang, Andrew Hanser, Edward A. Preble, N. Mark Williams, and Keith Evans

Appl. Phys. Lett. 90, 121118 (2007); http://dx.doi.org/10.1063/1.2715114 (3 pages) | Cited 6 times

Online Publication Date: 21 March 2007

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The authors present the fabrication and characterization of vertical-geometry Schottky-type ultraviolet (UV) photodetectors based on a bulk n-GaN substrate. By using low temperature rapid thermal annealing of the semitransparent Schottky contacts (nickel with 7% vanadium), they obtained an ultralow dark current of 0.56 pA at −10 V reverse bias. A responsivity of ∼ 0.09 A/W at zero bias was measured for wavelength shorter than the absorption edge of GaN, and it was found to be independent of the incident power in the range measured (50 mW/m2–2.2 kW/m2). The devices are visible blind, with an UV/visible contrast of over six orders of magnitude. An open-circuit voltage of 0.3 V was also obtained under a broadband UV illumination.
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85.60.Gz Photodetectors (including infrared and CCD detectors)

Defect-mediated surface morphology of nonpolar m-plane GaN

A. Hirai, B. A. Haskell, M. B. McLaurin, F. Wu, M. C. Schmidt, K. C. Kim, T. J. Baker, S. P. DenBaars, S. Nakamura, and J. S. Speck

Appl. Phys. Lett. 90, 121119 (2007); http://dx.doi.org/10.1063/1.2715126 (3 pages) | Cited 18 times

Online Publication Date: 21 March 2007

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The role of extended defects in determining the atomic scale surface morphology of nonpolar {1math00} m-plane gallium nitride has been elucidated. The heteroepitaxially grown m-GaN films are commonly reported to yield striated surface morphologies (slate morphology) correlated with their high densities of basal plane stacking faults. Here, the growth window was explored to allow nonslate morphologies for hydride vapor phase epitaxy. Lateral epitaxial overgrowth was then utilized to produce m-GaN films with three regimes of different extended defect contents. Elimination of stacking faults from the m-GaN yielded step-flow features with an average step height of 4–7 ML even for slate morphology growth conditions.
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68.55.-a Thin film structure and morphology
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.A- Nucleation and growth
68.47.Fg Semiconductor surfaces
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.72.Nn Stacking faults and other planar or extended defects

Study of self-diffraction process in photoconducting polymer-nematic liquid crystal hybrid structure

Jaroslaw Mysliwiec, Dorota Jarzab, Krzysztof Janus, and Stanislaw Bartkiewicz

Appl. Phys. Lett. 90, 121120 (2007); http://dx.doi.org/10.1063/1.2715127 (3 pages) | Cited 3 times

Online Publication Date: 21 March 2007

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The authors present results of the measurements of self-diffraction process inside the nematic liquid crystal cell with a photoconducting polymeric layer poly(N-vinylcarbazole) doped with trinitrofluorenone molecules. The dynamics of diffraction grating fading process versus applied voltage and different Ar+ laser power has been studied. Three-step process of grating’s fading was observed, connected with the charge carrier generation and their mobility in the photoconducting polymer. Theoretical calculations assuming proposed mechanism responsible for the grating decay are in a very good agreement with experimental results.
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42.70.Df Liquid crystals
42.70.Jk Polymers and organics
42.79.Dj Gratings

High quality AlGaN solar-blind Schottky photodiodes fabricated on AIN/sapphire template

H. Jiang and T. Egawa

Appl. Phys. Lett. 90, 121121 (2007); http://dx.doi.org/10.1063/1.2715479 (3 pages) | Cited 20 times

Online Publication Date: 21 March 2007

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The authors report the high-performance AlGaN solar-blind Schottky photodiodes grown on AIN/sapphire templates by metal organic chemical vapor deposition. The devices exhibit dark current densities as low as 1.6×10−11 A/cm2 at −5 V bias. The peak responsivity is 41 mA/W at 256 nm in the photovoltaic mode, corresponding to a quantum efficiency of 20%. A sharp spectral response cutoff of more than two orders of magnitude by 300 nm is observed under a low illumination intensity of 10 nW/cm2. The zero-bias resistance-area product of the device is found to be 5.0×1012 Ω cm2, leading to an estimated detectivity of 7.0×1014 cm Hz1/2/W at 256 nm.
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85.60.Dw Photodiodes; phototransistors; photoresistors
85.30.Kk Junction diodes

Isotropic photonic magnetoresistance

K. J. Chau, C. A. Baron, and A. Y. Elezzabi

Appl. Phys. Lett. 90, 121122 (2007); http://dx.doi.org/10.1063/1.2715533 (3 pages) | Cited 5 times

Online Publication Date: 21 March 2007

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The authors demonstrate isotropic photonic magnetoresistive behavior in the far-infrared transmission through ferromagnetic particle collections. Total suppression of the angular anisotropy, a fundamental characteristic of anisotropic magnetoresistance, is achieved in ensembles of highly porous, “cauliflower” shaped ferromagnetic particles. They reveal a morphological origin of the isotropic magnetic behavior using a phenomenological model in conjunction with three-dimensional calculations using Maxwell’s equations.
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75.50.Tt Fine-particle systems; nanocrystalline materials
75.47.Np Metals and alloys
75.30.Gw Magnetic anisotropy
75.50.Cc Other ferromagnetic metals and alloys
72.15.Gd Galvanomagnetic and other magnetotransport effects

Liquid-crystal-based linear polarization rotator

Hongwen Ren and Shin-Tson Wu

Appl. Phys. Lett. 90, 121123 (2007); http://dx.doi.org/10.1063/1.2713861 (3 pages) | Cited 8 times

Online Publication Date: 21 March 2007

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A liquid-crystal (LC)-based polarization rotator which can rotate the polarization axis of an incident linearly polarized light from 0° to 90° is demonstrated. In the LC cell, the top substrate has a uniform rubbing but the bottom substrate has two orthogonal rubbings which are separated by a nonrubbing zone. Between these two rubbed strips, the LC directors twist continuously from 0° to 90°. As a result, the optic axis of the incident linearly polarized light can be rotated continuously depending on the beam position.
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42.79.Kr Display devices, liquid-crystal devices
42.70.Df Liquid crystals
61.30.-v Liquid crystals

Generalized phase-shifting interferometry with arbitrary unknown phase shifts: Direct wave-front reconstruction by blind phase shift extraction and its experimental verification

X. F. Xu, L. Z. Cai, Y. R. Wang, X. L. Yang, X. F. Meng, G. Y. Dong, X. X. Shen, and H. Zhang

Appl. Phys. Lett. 90, 121124 (2007); http://dx.doi.org/10.1063/1.2716069 (3 pages) | Cited 10 times

Online Publication Date: 22 March 2007

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A simple wave-front reconstruction method by generalized phase-shifting interferometry (PSI) with arbitrary unknown phase shift between 0 and π for two adjacent frames is proposed. In this method the unknown phase shifts are extracted by a noniterative algorithm with the use of the interferograms and the intensities of object and reference waves, and then the original object field can be further obtained. This method is applicable for generalized PSI of any frame number N (N ≥ 2) and for both the amplitude and phase objects. Its effectiveness and accuracy are verified by both the computer simulations and optical experiments.
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07.60.Ly Interferometers

Coherent detection of terahertz pulses based on two-photon absorption in a photodiode

Arno Schneider and Peter Günter

Appl. Phys. Lett. 90, 121125 (2007); http://dx.doi.org/10.1063/1.2716070 (3 pages) | Cited 5 times

Online Publication Date: 22 March 2007

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The authors present a simple and robust method for the measurement of the terahertz-induced lensing effect that may be used for the coherent detection of few-cycle terahertz pulses. It is based on two-photon absorption of a 1.5 μm probe pulse in a standard silicon photodiode. The change in the spatial probe pulse profile caused by terahertz-induced lensing leads to a variation of the diode signal that is induced by two-photon absorption even though the total pulse energy has remained constant. This variation is shown to be proportional to the terahertz electric field.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
78.47.-p Spectroscopy of solid state dynamics
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
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