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30 Apr 2001

Volume 78, Issue 18, pp. 2617-2804

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Investigation of the emission mechanism in InGaN/GaN-based light-emitting diodes

T. Wang, J. Bai, S. Sakai, and J. K. Ho

Appl. Phys. Lett. 78, 2617 (2001); http://dx.doi.org/10.1063/1.1368374 (3 pages) | Cited 31 times

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The exciton-localization effect and quantum-confine Stark effect (QCSE) on the performance of InGaN/GaN-based light-emitting diodes (LEDs) have been investigated with regard to indium mole fraction and well thickness by means of temperature-dependent and excitation-power-dependent photoluminescence measurements. The exciton-localization effect can be enhanced by increasing the indium mole fraction or increasing well thickness but up to 2.5 nm. The QCSE is monotonically enhanced with increasing indium concentration or well thickness. The output power of the LED can be increased by the enhanced exciton-localization effect; however, the QCSE has much stronger influence on the output power of LEDs than the exciton-localization effect, which should be taken into account for further improving the performance of InGaN/GaN-based LEDs. © 2001 American Institute of Physics.
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85.60.Jb Light-emitting devices
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
78.20.Jq Electro-optical effects
71.35.-y Excitons and related phenomena

Far-infrared surface-plasmon quantum-cascade lasers at 21.5 μm and 24 μm wavelengths

Raffaele Colombelli, Federico Capasso, Claire Gmachl, Albert L. Hutchinson, Deborah L. Sivco, Alessandro Tredicucci, Michael C. Wanke, A. Michael Sergent, and Alfred Y. Cho

Appl. Phys. Lett. 78, 2620 (2001); http://dx.doi.org/10.1063/1.1367304 (3 pages) | Cited 81 times

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Quantum-cascade lasers operating above 20 μm (at λ∼21.5 μm and λ∼24 μm) wavelength are reported. Pulsed operation was obtained up to 140 K and with a peak power of a few milliwatts at cryogenic temperatures. Laser action originates from interminiband transitions in “chirped” superlattice active regions. The waveguides are based on surface-plasmon modes confined at a metal–semiconductor interface. The wavelengths were chosen in order to avoid major phonon absorption bands, which are particularly strong at energies just above the reststrahlen band. We also report on a 21.5-μm-wavelength laser based on a two-sided interface-plasmon waveguide. © 2001 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Optical parametric generation of femtosecond pulses up to 9 μm with LiInS2 pumped at 800 nm

F. Rotermund, V. Petrov, F. Noack, L. Isaenko, A. Yelisseyev, and S. Lobanov

Appl. Phys. Lett. 78, 2623 (2001); http://dx.doi.org/10.1063/1.1369386 (3 pages) | Cited 12 times

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We demonstrate direct access to the 4.8–9 μm spectral region with 800 nm, 1 kHz pumping of a femtosecond optical parametric amplifier based on the wide-gap wurtzite-type LiInS2. LiInS2 did not exhibit two-photon absorption at 800 nm and seems applicable at this pump wavelength with intensities of the order of 100 GW/cm2 for down-conversion of high energy ultrashort pulses up to its mid-IR edge at ≈12 μm. © 2001 American Institute of Physics.
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42.65.Yj Optical parametric oscillators and amplifiers
78.66.Li Other semiconductors

Nonlinear coaxial photonic crystal

Louis Poirier and Alain Haché

Appl. Phys. Lett. 78, 2626 (2001); http://dx.doi.org/10.1063/1.1367296 (3 pages) | Cited 13 times

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We demonstrate that large-scale photonic crystals can be used to simulate nonlinear optical effects occurring in real photonic crystals. A crystal made of coaxial segments with periodic impedance is used to create a stop band in transmission near 10 MHz. When a semiconductor rectifying diode is added to the crystal, a nonlinear mode of propagation appears within the forbidden band gap. It originates from a breaking of symmetry and an intensity-dependent attenuation similar to that encountered in saturable absorbers. Experimental results agree well with a theory based on a simple coupled-mass model with nonlinear resistive force. © 2001 American Institute of Physics.
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42.70.Qs Photonic bandgap materials
42.65.-k Nonlinear optics
78.20.-e Optical properties of bulk materials and thin films

Optical mode loss and gain of multiple-layer quantum-dot lasers

P. M. Smowton, E. Herrmann, Y. Ning, H. D. Summers, P. Blood, and M. Hopkinson

Appl. Phys. Lett. 78, 2629 (2001); http://dx.doi.org/10.1063/1.1366652 (3 pages) | Cited 22 times

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Using an electrically pumped multisection technique, we have directly measured the internal optical mode loss of semiconductor-laser structures containing 1, 3, 5, and 7 layers of uncoupled InGaAs quantum dots. The optical loss does not increase with the number of dot layers so higher net modal gain can be achieved by using multiple layers. The maximum modal gain obtained from the ground state increases with dot layer number from 10±4 cm−1 for a single layer to 49±4 cm−1 for the 7 layer sample, which is typical of the threshold gain requirement of a 350 μm long device with uncoated facets. © 2001 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
81.05.Ea III-V semiconductors
42.60.By Design of specific laser systems
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.21.La Quantum dots

Wafer bonded 1.55 μm vertical-cavity lasers with continuous-wave operation up to 105 °C

Adil Karim, Patrick Abraham, Daniel Lofgreen, Yi-Jen Chiu, Joachim Piprek, and John Bowers

Appl. Phys. Lett. 78, 2632 (2001); http://dx.doi.org/10.1063/1.1368377 (2 pages) | Cited 15 times

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We report 105 °C continuous-wave, electrically pumped operation of a 1526 nm vertical-cavity surface-emitting laser. An InP/InGaAsP active region was wafer bonded to GaAs/AlGaAs mirrors, with a superlattice barrier to reduce the number of nonradiative recombination centers in the bonded active region. © 2001 American Institute of Physics.
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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
78.66.Fd III-V semiconductors

Observation of sub-100-fs optical response from spin-coated films of squarylium dye J aggregates

Makoto Furuki, Minquan Tian, Yasuhiro Sato, Lyong Sun Pu, Hitoshi Kawashima, Satoshi Tatsuura, and Osamu Wada

Appl. Phys. Lett. 78, 2634 (2001); http://dx.doi.org/10.1063/1.1369621 (3 pages) | Cited 15 times

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For spin-coated films of squarylium dye J aggregates, ultrafast nonlinear optical responses were investigated by pump–probe measurements. By using a broadband mode-locked titanium:sapphire laser, we succeeded in observing the optical response with a time resolution of better than 60 fs. Time-resolved transmission data are shown for different excitation wavelengths, resonant to the excitonic absorption band and off-resonant. Relaxation times of the absorption saturation were evaluated to be 140 fs (fast component) and 950 fs (slow component) in the case of resonant excitation and 98 fs in the case of off-resonant excitation. © 2001 American Institute of Physics.
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42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
78.66.Qn Polymers; organic compounds
42.70.Jk Polymers and organics
42.79.Wc Optical coatings
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
78.47.-p Spectroscopy of solid state dynamics
71.35.Cc Intrinsic properties of excitons; optical absorption spectra

Wavelength tuning in InGaAs/InGaAsP quantum well lasers using pulsed-photoabsorption-induced disordering

T. K. Ong, Y. C. Chan, Y. L. Lam, and B. S. Ooi

Appl. Phys. Lett. 78, 2637 (2001); http://dx.doi.org/10.1063/1.1362329 (3 pages) | Cited 10 times

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Pulsed-laser irradiation followed by rapid thermal annealing was used to induce layer disordering of an InGaAs/InGaAsP laser structure. A band gap shift larger than 160 nm was achieved using energy densities of about 3.9 mJ mm−2 with 4800 pulses of laser irradiation. Transmission electron microscopy and photoluminescence were used to understand the possible effect of the laser irradiation on the material structure. Band gap-tuned lasers exhibiting blueshift up to 82 nm were obtained. This approach offers the prospect of a powerful and relatively simple postgrowth process for integrating multiple-wavelength lasers for wavelength-division-multiplexing applications. © 2001 American Institute of Physics.
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42.60.Fc Modulation, tuning, and mode locking
81.05.Ea III-V semiconductors
42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
42.60.By Design of specific laser systems
73.21.Fg Quantum wells
78.67.De Quantum wells
61.72.Cc Kinetics of defect formation and annealing
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Fk Semiconductors
71.20.Nr Semiconductor compounds

Theoretical performance and structure optimization of 3.5–4.5 μm InGaSb/InGaAlSb multiple-quantum-well lasers

A. D. Andreev, E. P. O’Reilly, A. R. Adams, and T. Ashley

Appl. Phys. Lett. 78, 2640 (2001); http://dx.doi.org/10.1063/1.1369146 (3 pages) | Cited 16 times

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We present a comprehensive theoretical investigation to optimize 3.5–4.5 μm InGaSb/InGaAlSb quantum-well (QW) lasers grown on ternary InGaSb substrates. We use an eight-band k⋅P Hamiltonian to calculate the Auger recombination and optical absorption coefficients in the active region, as well as the gain and threshold characteristics. The dominant Auger process involves hole excitation from the QW to unbound valence states. For structure optimization we varied the Ga content in the substrate and QW barrier layers. The optimized structure was obtained by maximizing the strain in the QWs, despite the Auger coefficient also increasing with strain. It is, therefore, demonstrated that the main aim for midinfrared laser optimization can be minimization of the threshold carrier density rather than reduction of the Auger coefficient. © 2001 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.20.At Surface states, band structure, electron density of states
68.35.Ct Interface structure and roughness

Switching dynamics of suspended mesogenic polymer microspheres

Darran R. Cairns, Merwin Sibulkin, and Gregory P. Crawford

Appl. Phys. Lett. 78, 2643 (2001); http://dx.doi.org/10.1063/1.1367292 (3 pages) | Cited 16 times

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Ordered polymer microspheres were produced by photo-polymerizing reactive nematic liquid crystal droplets suspended in glycerol, thus capturing the mesogenic order indefinitely. The electro-optic switching of these structures suspended in a fluid is investigated and described by a simple phenomenological model. © 2001 American Institute of Physics.
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61.30.Pq Microconfined liquid crystals: droplets, cylinders, randomly confined liquid crystals, polymer dispersed liquid crystals, and porous systems
42.70.Df Liquid crystals
78.20.Jq Electro-optical effects
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