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Quantum Electronics, IEEE Journal of

Issue 7 • Date July 1996

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Displaying Results 1 - 18 of 18
  • Wavelength-tunable asymmetric cladding ridge-waveguide distributed Bragg reflector lasers with very narrow linewidth

    Publication Year: 1996 , Page(s): 1225 - 1229
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (557 KB)  

    Narrow-linewidth ridge-waveguide distributed Bragg reflector (DBR) lasers with asymmetric cladding are demonstrated. This design requires only a single epitaxial growth of an asymmetric cladding laser structure while the grating and the ridge waveguide are fabricated after the growth. These lasers have a threshold current as low as 9 mA, a slope efficiency of 0.3 W/A, and a T/sub 0/ of 100 K. Wavelength tuning of 8 nm is achieved by current injection heating of the DBR section. A spectral-linewidth minimum of 36 kHz is achieved at an output power of 20 mW and is limited by linewidth rebroadening due to current injection in both the gain section and DBR section. View full abstract»

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  • Amplitude-modulation characteristics of barrier-reservoir and quantum-well electron-transfer (BRAQWET) modulators

    Publication Year: 1996 , Page(s): 1161 - 1167
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB)  

    We have studied theoretically and experimentally the intensity-modulation characteristics of GaAs-based light modulators based on the barrier-reservoir and quantum-well electron-transfer (BRAQWET) structure. The transmission-voltage characteristics are nonlinear and follow an inverse exponential relationship which is derived herein. It is also seen that a multiple-period BRAQWET structure is unnecessary and partially ineffective for amplitude modulation and that a one-period BRAQWET structure can give comparable results while providing more versatility for the device design. AlxGa1-xAs-based guided-wave modulators are demonstrated with a 50% modulation index at a drive voltage of 1 V View full abstract»

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  • Submillimeter p-Ge laser using a Voigt-configured permanent magnet

    Publication Year: 1996 , Page(s): 1203 - 1210
    Cited by:  Papers (11)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB)  

    A p-Ge laser at 170-200 μm wavelengths in Voigt configuration using a regular permanent magnet is reported. Results are compared with those obtained using a Faraday-configured superconducting magnet. Emission is observed over a wider range of electric-field magnitude in Voigt configuration at a given magnetic field. Time-resolved emission studies reveal unusual pulse dynamics which depend on the magnitude and duration of the applied electric field. Spectral content, Gaussian-beam profiles, and polarization are essentially independent of these temporal effects. A significant repetition-rate increase is found using copper heat sinks. An increased emission-pulse delay with increasing initial-sample temperature and the temperature independence of the emission quench time are both explained by Joule heating of the laser medium. Lasing persists above 10 K, raising the possibility of a practical p-Ge laser without need for liquid helium as a coolant View full abstract»

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  • Optoelectronic oscillator for photonic systems

    Publication Year: 1996 , Page(s): 1141 - 1149
    Cited by:  Papers (135)  |  Patents (56)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (904 KB)  

    We describe a novel photonic oscillator that converts continuous-light energy into stable and spectrally pure microwave signals. This optoelectronic oscillator (OEO) consists of a pump laser and a feedback circuit including an intensity modulator, an optical-fiber delay line, a photodetector an amplifier, and a filter. We present the results of a quasi-linear theory for describing the properties of the oscillator and their experimental verifications. Our findings indicate that the OEO can generate ultrastable, spectrally pure microwave-reference signals up to 75 GHz with a phase noise lower than -140 dBc/Hz at 10 KHz. We show that the OEO is a special voltage-controlled oscillator with an optical-output port and can be synchronized to a reference source by means of optical injection locking, electrical injection locking, and a phase-locked loop. Other OEO applications include high-frequency reference regeneration and distribution, high-gain frequency multiplication, comb frequency and pulse generation, carrier recovery, and clock recovery View full abstract»

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  • Mode-locking at very high repetition rates more than terahertz in passively mode-locked distributed-Bragg-reflector laser diodes

    Publication Year: 1996 , Page(s): 1211 - 1224
    Cited by:  Papers (88)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1196 KB)  

    We propose a technique for achieving mode-locking at very high repetition rates more than terahertz with high output power using a distributed-Bragg-reflector (DBR) laser, including an intracavity saturable absorber. This method is based on harmonic passive mode-locking at high gain levels and the selectivity of harmonic numbers related to the spectrum-filtering property of the intracavity Bragg reflector. Transform-limited pulses at repetition rates from 500 GHz to 1.54 THz were generated with an output power exceeding 15 mW. We studied stability of harmonic pulses by using conventional self-consistent mode-locking equations. We also discuss the effect of the spectrum-filtering properties of the intracavity Bragg reflector to the characteristics of mode-locked pulses View full abstract»

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  • Engineering of the nonradiative transition rates in modulation-doped multiple-quantum wells

    Publication Year: 1996 , Page(s): 1155 - 1160
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (412 KB)  

    The feasibility of the enhancement of the acoustic-phonon limited intersubband transition rate through impurity scattering has been theoretically investigated in double asymmetric-coupled quantum wells. The dependence of the acoustic-phonon rate on the barrier thickness and the effect of the position of the δ-doped region on the impurity rate have been treated rigorously. A 10-Å-doped region with a 10 10-cm-2-sheet density can enhance the acoustic-phonon transition limit by more than an order of magnitude. This allows for the design of intersubband lasers in which population inversion between acoustic-phonon limited discrete conduction-band states is achieved by impurity scattering and control of barrier thickness View full abstract»

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  • A new three-equation model for the CO2 laser

    Publication Year: 1996 , Page(s): 1126 - 1131
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    Three rate equations describing the single-mode CO2 laser dynamics are derived by applying the theory of linear filters to an improved four-level model. The model is studied in the case of periodic modulations of the losses and compared with the outcome of an experiment, revealing a good agreement View full abstract»

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  • Simultaneous ultraviolet and infrared emission in a sliding-discharge excited laser

    Publication Year: 1996 , Page(s): 1122 - 1125
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    Simultaneous laser action in the UV (337.1 nm and 357.7 nm) and the IR (2.6-3.1 μm) spectral ranges is observed in SF6-N 2-propane-butane mixtures directly excited by a sliding discharge. Output energies of 1.1 mJ in the ultraviolet and 12 mJ in the infrared are obtained simultaneously. Some performance parameters of the laser are presented View full abstract»

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  • Dynamic behavior of vertical-cavity surface-emitting lasers

    Publication Year: 1996 , Page(s): 1168 - 1179
    Cited by:  Papers (43)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (904 KB)  

    A quasi-three-dimensional dynamic model of index-guided vertical-cavity surface-emitting lasers is developed. Detailed structure of Bragg reflectors and lateral optical confinement are considered into the model. A three-dimensional waveguide problem is reduced to one dimension by using the effective-index method. The dynamic response of optical field is solved by the time-domain algorithm. In addition, the lateral variation of carrier concentration, refractive index, and spontaneous-emission profile are also determined in a self consistent manner. Using this model, the influence of carrier transport and hot carriers on the dynamic behavior of vertical-cavity surface emitting lasers is studied. It is found that these nonlinearities have significant influence on the relaxation-oscillation frequency and modulation bandwidth of the devices View full abstract»

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  • Optical feedback on self-pulsating semiconductor lasers

    Publication Year: 1996 , Page(s): 1191 - 1202
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1016 KB)  

    Weak optical-feedback effects on the statistical properties of self-pulsations in narrow-stripe semiconductor lasers are analyzed using Lang-Kobayashi-type equations. The self-pulsation features are compared with the characteristics of excited relaxation oscillations. We determine the operating regime in which the randomizing effect of spontaneous-emission noise destroys pulse coherence. In this regime, only phase-insensitive effects of optical feedback are possible, and optimum jitter reduction is achieved with delay times of the order of an integer-odd multiple of the free-running pulsation period. In the high-pump operating regime, interpulse coherence is retained and the optical-feedback phase is shown to be instrumental for pulse-jitter control. Our results show that for cavity lengths up to 10 cm, variations on the order of half an optical wavelength induce jitter variations of one order of magnitude View full abstract»

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  • Thermal effects in a coplanar-pumped folded-zigzag slab laser

    Publication Year: 1996 , Page(s): 1243 - 1252
    Cited by:  Papers (8)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1216 KB)  

    The properties of a coplanar-pumped folded-slab laser under the influence of thermal lensing have been modeled and measured. It is shown that despite the formation of a strong astigmatic lens within the slab, the results can be used to design resonators capable of good TEM00 performance, suitable for a wide variety of applications. Good agreement is found between modeling and measurement of slab and laser parameters. Using a novel technique, the fraction of absorbed pump power converted to heat has been measured under diode-laser pumping View full abstract»

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  • 1.5-μm strained-layer MQW-DFB lasers with high relaxation-oscillation frequency and low-chirp characteristics

    Publication Year: 1996 , Page(s): 1230 - 1236
    Cited by:  Papers (7)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    1.5-μm wavelength strained-layer multiple-quantum-well (SL-MQW) distributed-feedback (DFB) lasers for optical video distribution systems, including optical-fiber amplifiers, are studied with respect to the relaxation-oscillation frequency and wavelength chirp characteristics. Several types of lasers are examined as parameters of amount of strain, optical confinement, and detuning. It is confirmed that the introduction of negative detuning has an obvious effect on the increase in relaxation-oscillation frequency fr and the reduction in chirp ΔF. The SL-MQW DFB lasers with low optical confinement and negative detuning show extremely low FM response ΔF/ΔI of less than 60 MHz/mA as well as high fr over 10 GHz for the first time. Additionally, low-chirp value ΔF of 180 MHz with modulation depth of 10% is realized at relatively low bias current (Ih=Ith+30 mA) View full abstract»

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  • Tunneling-time asymmetry in resonant quantum structures

    Publication Year: 1996 , Page(s): 1150 - 1154
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    A generalized method for tunneling-time calculation has been developed that can be applied to an arbitrary shaped potential without the need of approximating it by multistep functions. In particular, this method is used to study the tunneling-time properties of asymmetric resonant quantum heterostructures View full abstract»

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  • Measurement and analysis of pump-dependent refractive index and dispersion effects in erbium-doped fiber amplifiers

    Publication Year: 1996 , Page(s): 1113 - 1121
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (564 KB)  

    In a doped fiber, at wavelengths close to an absorption, the refractive index, and hence the dispersion, is expected to be a strong function of wavelength, as described by the Kramers-Kronig relationship. Furthermore, this spectral variation itself will be a function of pumping. This paper describes an accurate and sensitive experimental determination of the pump dependence of the refractive index in an erbium-doped fiber amplifier. A Mach-Zehnder interferometric measurement is described where only one arm is comprised of doped fiber. Particular attention is paid to accounting for the significant difference in power levels in the two arms and the effects of polarization and incoherent light. The measured refractive-index change matches well with that theoretically predicted. The pumped and unpumped dispersion of the amplifier are calculated. While the extra dispersion is of similar magnitude to that of silica fiber, the impact on long telecommunications systems is likely to be negligible. However, this extra dispersion may be important in shorter systems such as soliton lasers. Given the good agreement between theory and experiment, the variation of dispersion with fractional inversion is calculated from absorption and gain measurements. The presence of codopants is known to alter the absorption and emission spectra; the effect on the dispersion is calculated, and a near linear dependence on germanium concentration is observed View full abstract»

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  • Scanning photoluminescence technique to determine the phase of the grating at the facets of gain-coupled DFB's

    Publication Year: 1996 , Page(s): 1237 - 1242
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    We demonstrate a rapid, nondestructive scanning photoluminescence (PL) technique for the determination of the phase of the grating at the cleaved or coated facets of “in-phase” gain-coupled distributed feedback lasers. The measured phases of the grating at the cleaved facets of a bar of lasers are found to be consistent with experimental measurements of laser performance View full abstract»

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  • Experimental characterization of coupled waveguides by normal-mode excitation

    Publication Year: 1996 , Page(s): 1132 - 1140
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (604 KB)  

    We present a novel method for measuring the coupling coefficient of a symmetric directional coupler, based on the direct excitation of the normal modes of the entire structure. The output-power distribution at different coupling lengths was related to the experimentally measured normal modes in order to find the coupling coefficient. The device was alternatively characterized by means of the individual-waveguide modes according to coupled-mode theory in the strong-coupling regime. Both methods were implemented on single-mode directional couplers in Ti:LiNbO 3. The validity and accuracy of both approaches are discussed View full abstract»

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  • Chirp and stability of mode-locked semiconductor lasers

    Publication Year: 1996 , Page(s): 1180 - 1190
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1076 KB)  

    A numerical study of mode-locked semiconductor lasers is presented with special attention to the chirp characteristics and to dispersion-related criteria for stable pulse-train emission. The dependence of the pulse chirp upon the refractive-index change, both with carrier density and carrier temperature changes, is discussed. The experimental observation of blue-chirped pulses for passive mode-locking in contrast to red-chirped pulses for active mode-locking is found to be due to the different contributions of gain and absorber media to the refractive-index change. In addition, it is revealed that the boundary of the stable operation regime is critically influenced by the spectral characteristics of laser and external cavity. Design considerations toward the achievement of high pulse energy, narrow spectral bandwidth, and linear chirp are given View full abstract»

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  • Practical issues in ultrashort-laser-pulse measurement using frequency-resolved optical gating

    Publication Year: 1996 , Page(s): 1253 - 1264
    Cited by:  Papers (31)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1116 KB)  

    We explore several practical experimental issues in measuring ultrashort laser pulses using the technique of frequency-resolved optical gating (FROG). We present a simple method for checking the consistency of experimentally measured FROG data with the independently measured spectrum and autocorrelation of the pulse. This method is a powerful way of discovering systematic errors in FROG experiments. We show how to determine the optimum sampling rate for FROG and show that this satisfies the Nyquist criterion for the laser pulse. We explore the low- and high-power limits to FROG and determine that femtojoule operation should be possible, while the effects of self-phase modulation limit the highest signal efficiency in FROG to 1%. We also show quantitatively that the temporal blurring due to a finite-thickness medium in single-shot geometries does not strongly limit the FROG technique. We explore the limiting time-bandwidth values that can be represented on a FROG trace of a given size. Finally, we report on a new measure of the FROG error that improves convergence in the presence of noise 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..

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Meet Our Editors

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