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Quantum Electronics, IEEE Journal of

Issue 7 • Date July 1997

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Displaying Results 1 - 25 of 27
  • Corrections To "Noise Of The Stretched Pulse Fiber Laser: Part I~theory"

    Publication Year: 1997 , Page(s): 1245
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  • Introduction To Molecular Electronics (Petty, M.C. et al, Eds.; 1995) [Book Review]

    Publication Year: 1997 , Page(s): 1246
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    Freely Available from IEEE
  • Design and fabrication of low-threshold 1.55-μm graded-index separate-confinement heterostructure strained InGaAsP single-quantum-well laser diodes

    Publication Year: 1997 , Page(s): 1141 - 1148
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    This paper presents a guideline for designing an optimum low-threshold 1.55-μm graded-index (GRIN) separate confinement-heterostructure (SCH) strained InGaAsP single quantum-well (SQW) laser diode (LD). The guideline was formulated based on the results of numerical and experimental analysis. After calculating the sheet carrier density at the lasing threshold, the guideline was obtained by considering the tradeoff between carrier and optical confinements in the well: the GRIN layer energy gap should be varied parabolically from InP to InGaAsP having a band gap wavelength of 1.1 μm to inject a large number of carriers into the well, and the thickness of one side of the GRIN layer should be more than 300 nm to keep a strong optical confinement. The GRIN SQW LD designed using the guideline has a Jth as low as 98 A/cm2 at a cavity length of 5 mm, which proves the guideline is effective for designing low-threshold 1.55-μm GRIN SQW LDs View full abstract»

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  • Analysis of DBR lasers and MOPA with saturable absorption gratings

    Publication Year: 1997 , Page(s): 1149 - 1155
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    The effect of saturable absorption in the grating regions of second-order surface-emitting DBR lasers and high-power M-MOPA, edge emitting with DBR master oscillator and flared amplifier, has been analyzed numerically. As the pumping current increases, light penetrates further into the end gratings, due to saturation, resulting in narrower far field and higher reflectivity. The latter, in turn, reduces the external differential efficiency. Thus, one obtains a nonlinear L-I curve which may also include bistability effect, especially for small pumping currents above threshold, with a large absorption coefficient and long gratings, in agreement with previously observed experimental data View full abstract»

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  • Photoluminescence of quasi-direct transitions in disordered In1-xGaxP/graded GaP alloys

    Publication Year: 1997 , Page(s): 1123 - 1131
    Cited by:  Papers (1)
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    We have examined the photoluminescence and photoluminescence kinetics of a series of In1-xGaxP alloys in an effort: 1) to elucidate the electronic structure of the conduction band versus alloy composition, especially near the direct-indirect crossover; 2) to determine precisely the composition of the direct-indirect crossover, and its temperature dependence; and 3) to understand the nonradiative decay mechanism and its temperature dependence. We find that the fundamental bandgap is only determined by the Γ1c and X1c states in samples with Ga-compositions ranging from 0.58 to 0.75, and that the 2-K direct-indirect crossover from Γ1c, to X1c occurs at x=0.69 and is not strongly temperature-dependent. Further, we find, in agreement with our spectroscopic ellipsometry measurements at room temperature, that the mixing near crossover is rather complicated and leads to the previous observation of quasi-direct transitions. Our combined photoluminescence and spectroscopic ellipsometry measurements have therefore clearly resolved the controversy regarding the bandgap crossover. This has strong implications for the realization of InGaP-based efficient light-emitting devices with emission at higher energies View full abstract»

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  • Operation and theoretical analysis of the multiple asymmetric coupled quantum-well light modulator in the n-i-n configuration

    Publication Year: 1997 , Page(s): 1084 - 1088
    Cited by:  Papers (3)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (80 KB)  

    Results of optical measurements on a multiple asymmetric quantum-well device in the n-i-n configuration that demonstrate for the first time its applicability as a light modulator are presented. The contrast ratio at the fundamental heavy hole exciton resonance is close to 2 for small operating voltage of around 3.5 V. Dual wavelength operation was proved possible with a weaker contrast ratio at 1.68 eV. The energy levels and the absorption coefficient are calculated in the envelope function approximation within the eight-band k×p model with electric field-dependent transition energies in agreement with theory. Weak deviations from the step-like character of the calculated absorption spectrum are explained by the wavevector dependence of the optical matrix element View full abstract»

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  • The effective frequency method in the analysis of vertical-cavity surface-emitting lasers

    Publication Year: 1997 , Page(s): 1156 - 1162
    Cited by:  Papers (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB)  

    An effective index model for vertical-cavity surface-emitting lasers (VCSELs) is reexamined. In a systematic manner, the basic equations are derived. Instead of effective indices of plane reference waveguides, effective frequencies of plane reference resonators appear. Calculations of the threshold gain and lasing wavelength of a long-wavelength VCSEL show the usefulness of the method and clarify the waveguiding mechanisms in VCSELs, Both dispersion and waveguiding influence the lasing wavelength remarkably View full abstract»

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  • Optimization and tolerance analysis of QCSE modulators and detectors

    Publication Year: 1997 , Page(s): 1094 - 1103
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    This paper describes the design constraints and optimization of multiple-quantum-well (MQW) devices for use as flip-chip bonded devices on silicon circuitry. These devices act as quantum-confined Stark effect (QSCE) modulators and detectors. It is shown that the optimal device thickness depends upon the biasing voltage levels as well as the voltage swing that is available from the silicon circuitry. Lower voltages favor thinner device designs. It was found that, for GaAs-AlGaAs quantum wells, a design in which the modulator and detector are of identical design, a combined efficiency of 0.36 could be achieved with a 5-V swing on the modulators, falling to 0.21 with 2.5 V. By using separate layers for the design of the modulator and detector, the performance could be improved significantly with 0.48 achievable for a 5-V swing. It is shown that optimizing the device to minimize nonuniformity effects makes the optimal design thinner View full abstract»

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  • Calculation of light distribution in optical devices by a global solution of an inhomogeneous scalar wave equation

    Publication Year: 1997 , Page(s): 1236 - 1244
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    A numerical scheme is suggested for solving the scalar wave equation for optical devices characterized by a z-dependent refractive index. The homogeneous wave equation is converted into a single-column inhomogeneous linear system by applying imaginary (absorbing) boundary potentials at the device boundaries. The imposed absorbing boundary conditions enable discrete representation of the device on a compact grid. Our scheme is based on applying an efficient sparse preconditioner to the linear system, which enables its global solution (i.e., simultaneously for all z values) by fast iterative methods, such as the quasi-minimal residual algorithm. A single solution of the inhomogeneous equation with the imaginary boundary operators allows the calculation of mode-specific as well as region-specific light-intensity coupling probabilities for initial mode of interest. Numerical examples illustrate the usefulness of the suggested scheme to the optimization of optical devices View full abstract»

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  • Reduction of nonlinear distortion in directly modulated semiconductor lasers by coherent light injection

    Publication Year: 1997 , Page(s): 1132 - 1140
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    A theoretical investigation of the second- and third-order intermodulation distortions (IMDs) in an injection-locked semiconductor laser under small-signal modulation is presented. The results show that a substantial reduction of the laser nonlinearity can be obtained, depending on both the injection level and frequency detuning between the master and slave lasers. The intensity modulation frequency response is also reported and shows that the injection-locked laser may also have a significantly improved behavior over the same free-running laser, revealed mostly in the reduced resonance peak and the broadening of the modulation bandwidth available View full abstract»

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  • Dependence of Ti-diffused Er:LiNbO3 laser efficiency on waveguide fabrication parameters and pump wavelength

    Publication Year: 1997 , Page(s): 1231 - 1235
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    The mode size, effective pump area, and coupling efficiency as function of initial Ti-stripe width W, diffusion temperature T, and initial Ti-stripe thickness H in c-cut Ti-diffused Er:LiNbO3 waveguide laser have been studied theoretically, taking into account optical pumping λp=1.477 μm and 0.98 μm. The main features of the mode sizes in terms of these diffusion parameters were collected and, as compared with the experimental results, a qualitative agreement has been achieved. The effective pump areas exhibit both significant initial Ti-stripe width and diffusion temperature dependence, especially for W>9 μm and T>1050°C, whereas the initial Ti-stripe thickness can hardly give influence when pumping with λp=0.98 μm radiation. On the other hand, coupling efficiency is approximately unchanged with values 0.76-0.78 for λp=1.477 μm and 0.8-0.85 for λ p=0.98 μm, indicating that there are no optimized values of these parameters to increase slope efficiency through coupling efficiency. Moreover, the 0.98 μm pumping reveal lower threshold and higher coupling efficiency than 1.477-μm pumping. Finally, the appropriate waveguide fabrication parameters were proposed for the fabrication of a more efficient laser View full abstract»

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  • Ytterbium-doped fiber amplifiers

    Publication Year: 1997 , Page(s): 1049 - 1056
    Cited by:  Papers (173)  |  Patents (30)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    The ytterbium-doped fiber amplifier offers a number of attractive features, including a broad-gain bandwidth and a high efficiency, due in large part to its freedom from various competing processes seen in other rare-earth dopants. Here we discuss the main features that influence design and possible applications of ytterbium-doped fiber amplifiers View full abstract»

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  • Ti3+ ion concentration and Ti:sapphire laser performance

    Publication Year: 1997 , Page(s): 1221 - 1230
    Cited by:  Papers (1)
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    The pulsed and CW laser performance of a range of titanium sapphire laser crystals is reported. Titanium ion concentration in the crystals ranged from 0.07 at.% to 0.25 and 0.41 at.% for some recently developed heavily doped crystals. Values of the crystal figure of merit lay between 30 and 220. Threshold, slope efficiency, tunability, and temporal response are assessed. Comparisons are made with the predictions of a simple rate equation model View full abstract»

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  • Parametric instability of optical amplifier noise in long-distance optical transmission systems

    Publication Year: 1997 , Page(s): 1068 - 1074
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    In this paper, the optical amplifier noise accumulation in long-distance optical transmission systems is analyzed under the influence of the parametric process caused by the Kerr effect and group-velocity dispersion. By considering the input signal as a continuous-wave (CW) carrier and the optical amplifier noise as the small modulation, the general theory on the evolution of the optical amplifier noise along the system is proposed. This theory enables us to treat all of the noise enhancement effects, the so called parametric instability, discussed so far in a unified manner. The validation of the theory is finally confirmed by using extensive computer simulations View full abstract»

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  • Design studies for distributed Bragg reflectors for short-cavity edge-emitting lasers

    Publication Year: 1997 , Page(s): 1180 - 1189
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    In conventional edge-emitting lasers, mirror reflectivity is ~0.3-0.4 so that very short cavities have an unacceptable loss. To decrease the mirror losses, one can conceive of an external distributed Bragg reflector (DBR) structure produced by etching. We examine the design considerations for such mirrors. Using a finite-difference time-domain (FDTD) scheme, we numerically simulate the propagation of a Gaussian wave packet in a laser cavity with an external DBR structure on one end. We find that despite the divergence of light at the semiconductor-air interface, high reflectivities (>90%) can be obtained using only a few mirrors, provided a low refractive index material (such as air) is one of the components of the DBR period. In our modeling, we include fluctuations based on factors such as lithographical error, etch error, and off-design wavelength lasing. Our results indicate that the external DBR is highly tolerant of such factors. In addition, simulations done using material with higher refractive index than air in the DBR structure indicate that it is possible for insulators to be deposited in the DBR structure, yet allow high reflectivity View full abstract»

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  • Electrooptic polarization modulation in [110]-oriented GaAs-InGaAs multiple quantum wells

    Publication Year: 1997 , Page(s): 1114 - 1122
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    An electrooptic modulator that is sensitive to the polarization state of transmitted light is demonstrated by using the intrinsic optical anisotropy of biaxially strained [110]-oriented GaAs-Iny Ga1-xAs multiple quantum wells. The ellipticity and the direction of polarization of a linearly polarized input pulse are modulated by a change in the in-plane dichroism and birefringence produced by a change in the voltage applied across the p-i-n region containing the quantum wells. Sensitive ellipsometric measurements are used to directly measure the anisotropy in the complex index of refraction between the two principal in-plane axes of the sample as a function of wavelength for selected voltages. The latter information is then used to determine the operating wavelength, the contrast ratio, the optical bandwidth, and the tunability of the modulator. This structure requires only standard elementary post-growth processing View full abstract»

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  • Dynamics and chaos stabilization of semiconductor lasers with optical feedback from an interferometer

    Publication Year: 1997 , Page(s): 1163 - 1169
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    This paper studies dynamical behaviors and noise properties of semiconductor lasers with optical feedback from an interferometer, i.e., two external cavities. Bifurcation diagrams versus external-cavity length and reflectivity reveal the existence of stable regions for fixed states and limit cycles. The steady-state analysis for a laser diode with two external feedbacks is performed, which shows that oscillation modes are locked at minimum excess gain modes. Oscillation frequencies of limit cycles show discrete transitions with the variation of ratios between two external-cavity lengths and reflectivities. It is proposed that such a model might be applied to stabilization of the feedback-induced chaos in external-cavity semiconductor lasers since the stable region is quite robust for wide parameter ranges. Intensity and phase noises are examined and the results indicate that the low-frequency relative intensity noise level and the linewidth can be greatly improved when the laser output is a fixed state or a limit cycle View full abstract»

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  • Theoretical analysis of timing jitter in monolithic multisection mode-locked DBR laser diodes

    Publication Year: 1997 , Page(s): 1216 - 1220
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    We present a theoretical analysis of the timing jitter in monolithic multisection mode-locked DBR lasers which is shown to agree well with experimental measurements. The analysis uses a traveling-wave equation model with Langevin spontaneous emission noise and includes the important physical effects of gain nonlinearities, self-phase modulation, and the presence of DBR filtering. It is found that spontaneous noise limits low-jitter operation. The impact of frequency detuning on the timing jitter is studied and the effects of laser parameters, such as linewidth enhancement factor and gain section length, are discussed for achieving low-jitter pulses View full abstract»

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  • The effect of compressive strain on the performance of p-type quantum-well infrared photodetectors

    Publication Year: 1997 , Page(s): 1104 - 1113
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    A detailed study of the performance of compressively strained p-type III-V quantum-well infrared photodetectors (p-QWIPs) is presented in this work. Three device structures composed of InGaAs-GaAs, InGaAs-AlGaAs, and InGaAs-AlGaAs-GaAs for normal incidence absorption have been fabricated and analyzed, with the results being compared with similar reported unstrained p-QWIPs. In all three QWIP structures, the quantum-well layers are under biaxial compressive strain ranging from -0.8% to -2.8%, while the barrier layers are lattice-matched to the substrate. The detection peaks of the quantum-well infrared photodetectors ranged from 7.4 to 10.4 μm. The detectors utilized the bound-to-continuum, bound-to-quasi-bound, and step bound-to-miniband intersubband transitions for infrared detection. The results showed that responsivities of up to 90 mA/W and detectivities from 109 to over 1010 cm√Hz/W are achieved under moderate applied bias and at reasonable operating temperatures (from 60 to 80 K), demonstrating the viability of the strained-layer p-doped quantum-well infrared photodetectors for staring focal plane array applications View full abstract»

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  • Amplitude squeezing from singly resonant frequency-doubling laser

    Publication Year: 1997 , Page(s): 1057 - 1067
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    We analyze amplitude squeezing from a singly resonant frequency-doubling laser oscillating at a single frequency. In this laser system, the cavity loss depends on the intensity of the oscillating fundamental field, so that conventional analyses based on a mean-field approximation become invalid in a highly pumped regime. To avoid this inconvenience, we consider spatial evolution of fields both in a laser medium and in a nonlinear crystal. It is predicted for the first time that a combination of excess nonlinearity and modest laser saturation can increase the output noise. We propose novel indices to evaluate the possible noise enhancement and suggest a design rule for squeezed light generation View full abstract»

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  • Excess noise in GaAs avalanche photodiodes with thin multiplication regions

    Publication Year: 1997 , Page(s): 1089 - 1093
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (100 KB)  

    It is well known that the gain-bandwidth product of an avalanche photodiode can be increased by utilizing a thin multiplication region. Previously, measurements of the excess noise factor of InP-InGaAsP-InGaAs avalanche photodiodes with separate absorption and multiplication regions indicated that this approach could also be employed to reduce the multiplication noise. This paper presents a systematic study of the noise characteristics of GaAs homojunction avalanche photodiodes with different multiplication layer thicknesses. It is demonstrated that there is a definite “size effect” for multiplication regions less than approximately 0.5 μm. A good fit to the experimental data has been achieved using a discrete, nonlocalized model for the impact ionization process View full abstract»

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  • Cold-cavity vectorial eigenmodes of VCSELs

    Publication Year: 1997 , Page(s): 1205 - 1215
    Cited by:  Papers (41)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    An analytical approximate solution of Maxwell's equations for the cold-cavity eigenmodes of cylindrical etched air-post vertical-cavity surface-emitting lasers (VCSELs) is presented. In radial and azimuthal directions, the modes correspond to the hybrid modes of cylindrical optical waveguides. A vectorial transform matrix approach is derived which takes into account coupling of bound eigenmodes in VCSEL structures. The method is illustrated for the case of noncoupled modes and the corresponding simplified transform matrix approach is used to calculate the field profiles in longitudinal direction and predict the resonance wavelengths for the VCSEL eigenmodes. Although approximate, the resulting eigenmodes may be viewed as a useful alternative to full numerical solutions, especially with regard to future more comprehensive modeling of VCSELs View full abstract»

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  • Statistics of transverse mode turn-on dynamics in VCSELs

    Publication Year: 1997 , Page(s): 1197 - 1204
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    The turn-on process of a multimode VCSEL is investigated from a statistical point of view. Special attention Is paid to quantities such as time jitter and bit error rate. The single-mode performance of VCSELs during current modulation is compared to that of edge-emitting lasers View full abstract»

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  • Spatio-temporal characteristics of filamentation in broad-area semiconductor lasers

    Publication Year: 1997 , Page(s): 1174 - 1179
    Cited by:  Papers (20)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    Using the time dependent rate equations appropriate for semiconductor lasers, we perform a linear stability analysis to derive an analytic expression for the filament gain as a function of the filament spacing, oscillation frequency, linewidth-enhancement factor, pumping level, and nonlinear refractive index. The spatio-temporal characteristics of filamentation are obtained for a given set of operating parameters by maximizing the filament gain. Our theory predicts that there is a critical value of the linewidth-enhancement factor below which broad-area lasers remain stable even at high pumping levels. Moreover, under certain conditions, the self-defocusing Kerr-type nonlinearity can be used to suppress filamentation even when the linewidth-enhancement factor exceeds this critical value View full abstract»

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  • Monte Carlo simulations of charge transport in high-speed lasers

    Publication Year: 1997 , Page(s): 1190 - 1196
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    A self-consistent ensemble Monte Carlo calculation of carrier transport in multiple-quantum-well lasers has been developed in an effort to understand the impact of picosecond carrier dynamics upon the modulation bandwidth. The model has been applied to InGaAsP-based devices which are designed to emit at 1550 nm. Results are discussed for structures with ungraded confinement layers of varied width and different numbers of QWs. Simulations have been carried out at fixed and also modulated bias, from which the intrinsic frequency response can be derived 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