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Quantum Electronics, IEEE Journal of

Issue 6 • Date June 2001

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Displaying Results 1 - 14 of 14
  • Editorial

    Page(s): 741
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    Freely Available from IEEE
  • Facet phases and sub-threshold spectra of DFB lasers: spectral extraction, features, explanations and verification

    Page(s): 762 - 769
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    The sub-threshold spectra of distributed feedback (DFB) lasers are heavily influenced by the phase of the internal grating with respect to the end facets. In this paper, we document features commonly observed in sub-threshold spectra and explain these features as manifestations of the facet phases. We extract estimates of facet phases by fitting a probability-amplitude transfer-matrix model to spectra from six truncated-well DFB lasers, and use the probability-amplitude model to document, isolate, and explain the sub-threshold spectral dependence on facet phase. To verify the accuracy of the approach that we have taken, we compare estimates of the facet phases from the fits to independent measurements of the facet phases using a scanning photoluminescence method. The results from the two methods are compared and are found to be in agreement. The agreement validates our use of the probability-amplitude model in this paper to explain laser facet phase phenomena View full abstract»

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  • High-frequency performance of lateral p-n junction photodiodes

    Page(s): 830 - 836
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    We developed an analytical device model for quantum well lateral p-n junction photodiodes (LJPDs). The model takes into account the features of the carrier transport in LJPDs and their geometry, which ensure short transit times and a low capacitance. This model is used for calculating the LJPD's characteristics as functions of the signal frequency, bias voltage, and structural parameters and for the estimation of the LJPD ultimate performance View full abstract»

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  • Integration of waveguide-type wavelength demultiplexing photodetectors by the selective intermixing of an InGaAs-InGaAsP quantum-well structure

    Page(s): 824 - 829
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    Using the selective intermixing of an InGaAs-InGaAsP multiquantum-well (MQW) structure, a wavelength demultiplexing photodetector which can demultiplex two widely separated wavelengths was fabricated. An InGaAs-InGaAsP MQW with a u-InP cladding layer and a n-InGaAs cap layer, grown by metal organic chemical vapor deposition was used. Selective area intermixing of the InGaAs-InGaAsP MQW structure was done by a rapid thermal annealing after the deposition and patterning of the SiO2 dielectric layer on the InGaAs cap layer. The integrated structure consists of shorter and longer wavelength sections, separated by an absorber section. Shorter wavelength and absorber sections were intermixed with the SiO2 dielectric layer. At a wavelength of 1477 nm, the output photocurrent ratio was enhanced as the length of the absorber region increased and a ratio of over 30 dB was observed, while at a wavelength of 1561 nm, an output photocurrent ratio of 18.9 dB was observed View full abstract»

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  • Nonlinear operation of a planar circular-grating DBR laser

    Page(s): 742 - 751
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    An approximate method for the analysis of the nonlinear operation of a planar circular-grating distributed Bragg reflector laser is presented. The analysis is based upon vector-wave self-consistent coupled-mode equations modified to take into account gain saturation effects. With the help of an energy theorem and threshold field approximation, an approximate formula relating small-signal gain to the output power and laser parameters is derived. The laser characteristics obtained reveal behavior of the optimal coupling strength of the Bragg reflector, which provides maximal power efficiency as a function of the laser parameters. It is also shown that the gain saturation effect provides mode selectivity in the laser structure View full abstract»

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  • Interferometric measurements of displacement on a diffusing target by a speckle tracking technique

    Page(s): 800 - 806
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    Operation of a laser interferometer with a noncooperative target surface, and on a substantial span of displacement (1 m), is reported for the first time to our knowledge. In the paper, we first analyze the errors of an interferometer operating in the speckle pattern regime, then propose the technique of tracking the speckle relative maximum amplitude as a solution for problems so far preventing interferometric measurements of large displacements. Examples of the speckle-statistics improvements are reported. Residual errors are of the order of few wavelengths on a 1-m displacement, indicating that a 10-6-class instrument can be developed. The proposed approach has been implemented with an injection interferometer View full abstract»

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  • A model for diffraction-limited high-power multimode fiber amplifiers using seeded stimulated Brillouin scattering phase conjugation

    Page(s): 781 - 789
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    Diffraction-limited polarized stimulated Brillouin scattering (SBS) Stokes output from a multimode fiber is possible when the Stokes beam is the phase conjugate of diffraction-limited polarized pump light from a narrow-band master oscillator. Net amplification can be obtained by interposing a gain medium, such as a fiber amplifier between the master oscillator and the region of SBS generation. This paper proposes and studies numerically a model which describes the space-time dynamics of SBS generation, including phase conjugation, attenuation, phonon decay, thermal noise, inhomogeneous broadening, and amplifier gain. Noise reduction and phase locking are obtained by seeding the low-power end of the fiber at the Stokes frequency. Simulations are described for the case of 1.064 μm light amplification in a dual-clad Yb-doped multimode fiber amplifier View full abstract»

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  • Resolving power and sensitivity in modulation transfer stimulated resonant Raman spectroscopy

    Page(s): 837 - 843
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    We show that the lineshape and size of the detected signal in ultra-high-resolution stimulated Raman spectroscopy computed from a general expression of the modulated signal are in good agreement with the experimental results. Using the theoretical expression of the signal, we analyze the resolving power and the sensitivity of our Raman spectrometer. We show that a second harmonic detection in high-frequency transfer modulation generates a lineshape without modulation broadening. A 2.6-kHz-wide resonance has been obtained with iodine, mainly limited by both the transit time and collisions View full abstract»

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  • The effect of wiggler imperfections on nonlinear harmonic generation in free-electron lasers

    Page(s): 790 - 793
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    The generation of harmonics through a nonlinear mechanism driven by bunching at the fundamental has sparked interest in using this process as a path toward an X-ray free-electron laser (FEL). An important issue in this regard is the sensitivity of the nonlinear harmonic generation to wiggler imperfections. Typically, linear instabilities in FELs are characterized by increasing sensitivity to both electron beam and wiggler quality with increasing harmonic number. However, since the nonlinear harmonic generation mechanism is driven by the growth of the fundamental, the sensitivity of the nonlinear harmonic mechanism is not severely greater than that of the fundamental. In this paper, we study the effects of wiggler imperfections on the nonlinear harmonics in a 1.5-Å FEL, and show that the decline in the third harmonic emission with increasing levels of wiggler imperfections roughly tracks that of the fundamental View full abstract»

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  • Total reflection cannot occur with a negative delay time

    Page(s): 794 - 799
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    It was recently predicted [ in ibid., vol. 33, p. 519, 1997] that the frustrated Gires-Tournois interferometer exhibits a negative delay time for reflection. Given its 100% reflectivity, this appears to contradict causality. We demonstrate that an additional, positive, contribution comes from consideration of the transverse dimension. We prove that this contribution is always large enough to enforce a positive total delay View full abstract»

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  • Deep-etched distributed Bragg reflector lasers with curved mirrors. Experiments and modeling

    Page(s): 752 - 761
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    A semiconductor laser with deep-etched distributed Bragg reflectors (DBRs) supporting a planar Gaussian mode has been experimentally and theoretically studied. A 90-μm-long laser with two-groove DBRs has a low threshold current of 7 mA and a maximum side mode suppression of 17.6 dB under continuous operation. The laser resonator supports a mode that closely resembles the desired planar Gaussian mode. The reflectivities of the deep-etched DBRs were experimentally determined using broad area devices, and the reflection, transmission, and scattering properties of the DBRs were simulated using a finite-difference time-domain model. The simulations show that deep grooves, covering the full transverse extent of the guided mode, are needed to maximize the reflectivity and to minimize the scattering loss. A beam-propagation model was used to simulate the laser resonator. The simulations (as well as the experiments) show that the laser is sensitive to thermal effects. Thermal lensing narrows the mode waist, and therefore increases the spatial hole burning in the center of the resonator where the intensity is at its maximum. At high drive currents, this leads to a degradation of the spatial mode quality. The simulations also indicate that a laser with optimized DBRs (one one- and one two-groove DBRs with an etch depth of 1 μm) would have a threshold current less than 2 mA and support a high-quality planar Gaussian mode to an output power of 9 mW under continuous operation View full abstract»

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  • Analysis of multiple wavelength DFB fiber lasers

    Page(s): 770 - 780
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    The behavior of multiwavelength distributed feedback fiber lasers is simulated in a comprehensive numerical model. Multiple fundamental modes can coexist, even though the coupling coefficients of their respective refractive index gratings are not equal, due to induced dynamic gain gratings. We have investigated the effect on the lasing state of variations in coupling strengths, gain parameters, grating Bragg frequency separation, relative phase between the gratings, length of the structure relative to the beat lengths between the gratings, grating center phase-shift errors, and saturation level of the UV-induced refractive index change View full abstract»

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  • Temperature dependence of electroluminescence in a tris-(8-hydroxy) quinoline aluminum (Alq3) light emitting diode

    Page(s): 807 - 812
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    Organic electroluminescent devices using tris-(8-hydroxy) quinoline aluminum (Alq3) as the emissive layer and N,N'-diphenyl-N,N' bis (3-methylphenyl)-[1-1'-biphenyl]-4-4'-diamine as the conventional hole transport layer have been fabricated. The temperature- and field-dependent quantum efficiency have been investigated over the temperature range from 1 to 300 K using a model developed by Shen et al. to explore the physics at the organic heterointerface in the present device structure with the formation of an accumulation layer. It has been observed that electron luminescence intensity decreases with decreasing temperature down to 160 K, then saturates in the low-temperature region. The quantum efficiency increases with decreasing temperature and finally reaches an almost constant value. From the analysis, it is seen that the model can explain the luminescence behavior of the device satisfactorily down to 120 K but fails to explain the low-temperature behavior. The efficiency has also been studied with voltage and it is seen that there is an optimum voltage required to get the maximum efficiency View full abstract»

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  • Optimum noise performance of optical amplifiers

    Page(s): 813 - 823
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    The concept of noise figure F and noise measure M applicable to radio frequency and microwave amplifiers is reviewed and extended to cover optical amplifiers. Two noise figures are defined in the optical regime: one gives the ASE output, while the other gives the ratio of signal-to-noise ratios at the input and output. In the quantum regime, the lower limit on these optimum values is set by a generalization of Heisenberg's uncertainty relation. A Raman back-pumped fiber link with post-amplification with an erbium-doped fiber amplifier is used to illustrate the use of noise measure View full abstract»

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Aims & Scope

The IEEE Journal of Quantum Electronics is dedicated to the publication of manuscripts reporting novel experimental or theoretical results in the broad field of the science and technology of quantum electronics..

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Aaron R. Hawkins
Brigham Young University