Scheduled System Maintenance:
Some services will be unavailable Sunday, March 29th through Monday, March 30th. We apologize for the inconvenience.
By Topic

Quantum Electronics, IEEE Journal of

Issue 12 • Date Dec 1990

Filter Results

Displaying Results 1 - 25 of 33
  • Propagation and stability of optical pulses in nonlinear planar structures with instantaneous and finite response times

    Publication Year: 1990 , Page(s): 2115 - 2129
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1020 KB)  

    The propagation of optical pulses in nonlinear waveguide and directional coupler structures consisting of linear and self-focusing media is studied numerically. Instantaneous and integrating nonlinearities are considered. A comparison of the stability of waveguide modes and coupling characteristics under such conditions is made. Finite medium responses times are shown to lead to an increase in the stability of pulses propagating in waveguide structures. For directional coupler geometries it is shown that finite response times lead to a loss of definition between the cross and bar states as the coupling efficiencies of more intense pulses are increased. These effects are found to be dependent on the initial, spatial, and temporal pulse profiles View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Determination of the threshold for instability in four-wave mixing mediated by Brillouin scattering

    Publication Year: 1990 , Page(s): 2130 - 2137
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (692 KB)  

    The threshold for instability in Brillouin-enhanced four-wave mixing has been experimentally determined as a function of both the phase mismatch and the ratio of the pump beam intensities and is shown to agree with theoretical modeling. The effective input noise intensity for four-wave mixing in the unstable regime is compared to the noise in a stimulated Brillouin scattering amplifier and is found to be higher by a factor of three in the forward direction. Competition between two input signals has been investigated, and it is shown that the signal which arrives first dominates the interaction in the unstable regime View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Transverse-mode competition effects observed in the numerical simulation of transients in gain-guided semiconductor laser arrays

    Publication Year: 1990 , Page(s): 2075 - 2085
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1024 KB)  

    A numerical analysis of transient turn-on in a gain-guided semiconductor laser array is presented. The self-consistent approach, valid in the strong-coupling limit, treats the array as a single waveguide laser with a transversely varying refractive index. The program first solves for the modes of this system without considering stimulated emission. The overall modal gain is then inserted into the rate equations in order to calculate a photon density; this results in a new spatial gain distribution, which in turn causes changes to the modal intensity profiles. This analysis is used to find both steady-state results and instabilities which result from mode competition. The approach is to solve instantaneous eigenvalue equations View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ablation of the cornea and synthetic polymers using a UV (213 nm) solid-state laser

    Publication Year: 1990 , Page(s): 2284 - 2288
    Cited by:  Papers (2)  |  Patents (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1188 KB)  

    A study is made of photoablation of the porcine cornea and synthetic collagen with 213-nm radiation generated by the fifth harmonic from a Q-switched Nd:YAG laser. The new nonlinear crystals, beta barium borate (BBO), with specific angle cutting were used to optimize the fifth-harmonic generation (213 nm). For comparison purposes, the above materials were also ablated by 266-nm (fourth-harmonic) laser radiation. Light and electron microscopy demonstrated that the damage zones created by 213- and 266-nm radiation are <1 and 15 μm, respectively. The ablation similarity between 193 and 213 nm opens major opportunities for the development of a new corneal sculpting system based on solid-state laser technology which will overcome difficulties associated with excimer lasers View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optical reflectance and transmittance of tissues: principles and applications

    Publication Year: 1990 , Page(s): 2186 - 2199
    Cited by:  Papers (22)  |  Patents (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1464 KB)  

    A discussion is presented of diagnostic and dosimetric optical measurements in medicine and biology. Topics covered include: tissue optical properties, tissue boundary conditions, and invasive versus noninvasive measurements. Clinical applications of therapeutic dosimetry and diagnostic spectroscopy are discussed. The principles of diffuse reflectance and transmittance measurements are presented. Experimental studies illustrate reflectance spectroscopy and steady-state versus time-resolved measurements View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Laser trapping in cell biology

    Publication Year: 1990 , Page(s): 2148 - 2157
    Cited by:  Papers (11)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1164 KB)  

    Optical traps offer the promise of being used as noninvasive micromanipulators for biological objects. An analytical model was developed that accurately describes the forces exerted on dielectric microspheres while in a single-beam gradient force optical trap. The model can be extended to the trapping of biological objects. The model predicts the existence of a stable trapping point and effective trapping range. A minimum trapping power of ~5 mW and an effective trapping range of 2.4 μm were measured for 10-μm-diameter dielectric microspheres and are in reasonable agreement with expected results. In cell biology, the optical trap was used to alter the movement of chromosomes within mitotic cells in vitro and to hold motile sperm cells. Results for the mitotic cells indicate that chromosome movement was initiated in the direction opposite to that of the applied force View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Laser femtosecond MPI mass spectroscopy of dye-labeled nucleotides

    Publication Year: 1990 , Page(s): 2158 - 2161
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    The laser multiphoton photoionization (MPI) mass spectroscopy technique was used to investigate the processes of photoionization and fragmentation of the nucleotides chemically bound to the label chromophore group. The results of experiments with nucleotide-coumarin complexes are presented. The experiments involved four nucleic acid bases-adenosine, cytosine, guanine, and thymine-bound to the coumarin 120 dye chromophore. To obtain the mass spectra of the model compounds, use was made of 300-fs laser pulses at 308 nm. The results obtained were compared with the mass spectra resulting from the irradiation of the samples with 15-ns pulses at 266 or 355 nm. The mass spectra obtained are shown and discussed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the probabilistic characterization of side mode fluctuations in pulse-modulated nearly-single-mode semiconductor lasers

    Publication Year: 1990 , Page(s): 2046 - 2051
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    Occasionally, a weak side mode in a pulse-modulated nearly-single-mode semiconductor laser can process a significant portion of the total laser output power during the leading edge of a pulse. When combined with the group velocity dispersion of single-mode optical fibers, this mode partitioning can influence the bit error ratio performance of high-speed lightwave systems. Simulation-based solutions of stochastic rate equations, which describe the modulation dynamics of the laser, are used to characterize the side-mode fluctuations probabilistically View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Subnanosecond probing of the ablation of soft plaque from arterial wall by 308 nm pulses delivered through a fiber

    Publication Year: 1990 , Page(s): 2279 - 2283
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1444 KB)  

    Ablation and etching in air by pulsed, ultraviolet (308-nm) laser radiation of the surface of a sample of soft plaque attached to the arterial wall were probed by pulses of visible laser radiation (596 nm; <1 ns FWHM). The ultraviolet radiation was delivered to the sample by an optical fiber 600 μm in diameter. The results of the probing were recorded photographically. Ablation and etching in air of the intimal wall by laser pulses at the same wavelength were also probed in the same manner for comparison. When the fiber tip was 0.5 mm above the sample surface, the ablation that was caused by the laser pulse was readily seen as a blast wave of expanding gases that was followed by the ejection of solid particulates View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Axicon: a new laser beam delivery system for corneal surgery

    Publication Year: 1990 , Page(s): 2305 - 2308
    Cited by:  Papers (2)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    A new laser beam delivery system using axicon beam shaping has been designed to produce controllable surface ablation as well as trephination for the corneal surgery. Noncontact cornea trephination was performed on human eye-bank eyes by using a Q-switched Er:YAG laser with a axicon-lens combination. The results shows that the uniformity of the trephination along the ring depends on the radial symmetry of the beam. The histological results of the samples show that the damage zone of the laser cut is less than 10 μm. This demonstrates the possibility of replacing mechanical trephination in corneal surgery View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dependence of the linewidth of a semiconductor laser on the mode distribution

    Publication Year: 1990 , Page(s): 2058 - 2064
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    A theory and measurements that show the dependence of the frequency noise spectrum and, therefore, of the semiconductor laser linewidth on the mode distribution are presented. The theory is based on rate equations where the linewidth is strongly influenced by the gain saturation coefficients (nonlinear gain). Analytical results are restricted to two modes. Measurements show that the linewidth change of the main mode depends on the wavelength side of the side mode (related to the wavelength mode of the main mode) and the effect decreases with increasing mode separation. Furthermore, the theoretical and measured frequency noise spectra of a three-mode laser are depicted, showing a characteristic resonance peak for certain mode distributions. This property of the frequency noise spectrum is also described by the theory View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparison of tissue ablation with pulsed holmium and thulium lasers

    Publication Year: 1990 , Page(s): 2271 - 2275
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    The ablation rates and tissue effects produced by a pulsed holmium laser (wavelength 2.12 μm, pulse duration 250 μs) and a pulsed thulium laser (wavelength 2.01 μm, pulse duration 250 μs) were compared. Because the absorption coefficient of water is almost three times greater at the shorter wavelength (65 versus 24 cm-1), the thulium laser should have a significantly lower threshold of ablation and produce significantly less residual thermal injury. These hypotheses were tested in vitro. Ablation rates were measured using fresh liver and a mass loss technique were found to increase linearly with delivered radiant exposure. The threshold radiant exposure for ablation was derived from the mass loss measurements and found to be 36 J/cm2 for the holmium laser and 29 J/cm2 for the thulium laser. The corresponding heats of ablation were 10 kJ/cm3 for the holmium laser and 9.7 kJ/cm3 for the thulium laser View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effects of near-infrared laser and superluminous diode irradiation on Escherichia coli division rate

    Publication Year: 1990 , Page(s): 2162 - 2165
    Cited by:  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    An investigation is conducted of the effect of a 1300-nm continuous-wave (CW) laser diode 950-nm modulated superluminous diode which had a fixed average power density of 1.2×103 W/m 2 at all variable repetition rates of 2, 26, 700, 1000, and 5000 Hz and had an equivalent pulse duration of 410, 31.1, 1.15, 0.82, and 0.16 ms, respectively. The effect of both diodes on the rate of Escherichia coli WP2 division was examined. It was found that the radiation of the CW mode of the 1300-nm laser diode increased the division of E. coli in the dose range of 0.9-9.0 J/cm2. The 950-nm pulsed irradiation increased or inhibited the division rate of bacteria depending on the pulsing frequency and/or pulse duration View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The effects of spatial hole burning and energy diffusion on the single-mode operation of standing-wave lasers

    Publication Year: 1990 , Page(s): 2052 - 2057
    Cited by:  Papers (15)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    Spatial hole burning in the absence of energy diffusion is examined. A formula is derived which predicts how far above threshold a homogeneously broadened standing-wave laser operates in a single-longitudinal mode. This is a conservative formula, since energy diffusion decreases the effects of spatial hole burning and increases the power level at which single-mode operation can be maintained. The role of energy diffusion is also examined. A formula is derived for how far above threshold a standing-wave laser oscillates in a single-longitudinal mode when energy diffusion is accounted for. Examples of the use of these formulas are given View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Gain saturation characteristics of traveling-wave semiconductor laser amplifiers in short optical pulse amplification

    Publication Year: 1990 , Page(s): 2086 - 2094
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    The gain saturation characteristics of traveling-wave semiconductor laser amplifiers (TWAs) are theoretically and experimentally investigated. In the amplification of an isolated pulse whose repetition period is short compared to the carrier lifetime, the gain saturation is related through the carrier lifetime to the gain saturation in CW amplification. When the output pulse energy is smaller than the saturation energy, short optical pulses can be amplified without pulse shape distortion, whereas high-energy pulses suffer from pulse shape distortion due to the temporal gain variation during the pulse radiation. FWHM pulse duration variation in amplification by TWAs depends on the input pulse shape. The pulse energy gain saturation was experimentally confirmed to be independent of pulse durations and to be determined only by the pulse energy. In extremely-high-repetition-rate pulse amplification, the saturation of the pulse energy gain is determined by the average signal power View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Liquid core light guide for laser angioplasty

    Publication Year: 1990 , Page(s): 2289 - 2296
    Cited by:  Papers (2)  |  Patents (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (956 KB)  

    It is shown that delivery of laser energy to intravascular targets through a flowing fluid-core laser angioplasty catheter offers new design possibilities and solutions to current practical problems facing laser angioplasty. Fluid-core catheters using iodinated radiographic contrast material as the core fluid can transmit high-peak-power visible laser pulses at high efficiencies while offering improved imaging of the target and distal vasculature. These catheters are simple to produce, are optically and mechanically stable, and are compatible with conventional angioplasty equipment and techniques. In canine coronary arteries in vivo, the catheters proved to be flexible, atraumatic, and able to deliver ablative high-peak-power laser pulses View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The propagation of bright and dark solitons in lossy optical fibers

    Publication Year: 1990 , Page(s): 2109 - 2114
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    An analytic perturbation solution to the nonlinear Schrodinger equation with loss Γ for both normal and anomalous dispersion is developed. Explicit results are obtained through second order in the perturbation Γ. The results show that the dark pulse spreads less rapidly than the bright one and that total spreading as well as the difference in spreading rate for the two types of pulses decreases with loss. Comparisons are made with a zeroth-order perturbation theory and with numerical simulations, which are found to bracket the second-order results View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic optical soliton communication

    Publication Year: 1990 , Page(s): 2095 - 2102
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB)  

    Digitally coded optical solitons at 5 and 10 Gb/s have been successfully transmitted over 400 and 300 km, respectively, using erbium-doped fiber amplifiers and repeaters. The soliton pulse source is a gain-switched distributed-feedback laser diode with spectral windowing. The repeater spacing for the 10-Gb/s transmission with an input soliton of A=1.4 is 25 km, which is extended to 50 km for 5-Gb/s transmission with an input soliton of N=1.8-2.0 View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nonlinear analysis of surface-emitting distributed feedback lasers

    Publication Year: 1990 , Page(s): 2065 - 2074
    Cited by:  Papers (4)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB)  

    An analysis of surface-emitting distributed feedback lasers under conditions above threshold is presented. The coupled-wave equations are integrated numerically using a self-consistent technique that includes the effects of gain saturation, carrier diffusion, antiguiding, and free carrier loss. The laser threshold current and slope efficiency are determined as a function of the strip length and p-layer thickness where it is found that the device efficiency can be very high. Antiguiding, which varies when the grating is mistuned with respect to the gain peak, influences the slope, threshold, and shape of the emission far field. Small variations in the longitudinal index of refraction are shown to affect the far-field intensity profile significantly View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ultralong dispersion-shifted erbium-doped fiber amplifier and its application to soliton transmission

    Publication Year: 1990 , Page(s): 2103 - 2108
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    Distributed, dispersion-shifted erbium-doped fiber amplifiers with doping concentrations as low as 0.1-0.5 p.p.m. (0.1-0.5×10-4 wt.%) were fabricated and their grain characteristics studied for the purpose of soliton amplification. A 9.4-km dual-shape-core-type amplifier with a 0.5-p.p.m. concentration had a gain of more than 20 dB at 1.535 μm and 10 dB at 1.552 μm with a forward pumping configuration, and it could successfully amplify and transmit a 20-ps soliton pulse train at a 2.5-GHz repetition rate. The soliton transmission characteristics of an 18.2 km long fiber amplifier were studied using backward and forward pumping. It was found that A=1.5 soliton pulses with a pulse width of 20 ps could be amplified over 18.2 km at a repetition rate of 5 GHz, where soliton narrowing to 16 ps was observed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A review of the optical properties of biological tissues

    Publication Year: 1990 , Page(s): 2166 - 2185
    Cited by:  Papers (90)  |  Patents (125)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1324 KB)  

    The known optical properties (absorption, scattering, total attenuation, effective attenuation, and/or anisotropy coefficients) of various biological tissues at a variety of wavelengths are reviewed. The theoretical foundations for most experimental approaches are outlined. Relations between Kubelka-Munk parameters and transport coefficients are listed. The optical properties of aorta, liver, and muscle at 633 nm are discussed in detail. An extensive bibliography is provided View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Measurement of laser ablation threshold with a high-speed framing camera

    Publication Year: 1990 , Page(s): 2276 - 2278
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    A method for measuring laser ablation threshold energy with a high-speed framing camera is presented. To demonstrate the utility of the technique, the threshold energy for pulsed holmium laser ablation of liver was measured. The measured threshold radiant exposure of 30±3 J/cm2 is in good agreement with values previously determined by alternate techniques. In addition to providing a rapid and reproducible measurement of laser ablation threshold, this technique also provides insight into the physical mechanisms of ablation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Time-resolved fluorescence spectroscopy of the retinal pigment epithelium: age-related studies

    Publication Year: 1990 , Page(s): 2218 - 2225
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (952 KB)  

    Time-resolved fluorescence spectroscopy shows promise as a high-sensitivity, high-discrimination tool for diagnostic purposes. The application of this technique to the study and the diagnosis of aging processes within ocular tissues is investigated. An age-related study of the pigments (melanin, lipofuscin, and melanolipofuscin) of the retinal pigment epithelium, performed using time-resolved fluorescence spectroscopy with picosecond gating, is presented. The study was performed on intact pigment granules, extracted with soft procedures, and the results have been correlated with the ultrastructure of the granules and with the results of continuous-wave absorption and fluorescence spectroscopy. Both classes of pigments exhibit age-related fluorescence properties View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ball-tipped fibers for laser angioplasty with the pulsed-dye laser

    Publication Year: 1990 , Page(s): 2297 - 2304
    Cited by:  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1212 KB)  

    A method of introducing high-intensity laser radiation into arteries has been developed and tested in amputated human limbs. The device consists of a small-diameter, flexible, quartz optical fiber which tapers to a large-diameter, smooth, rounded-ball tip. The small-ball tip minimizes the chance of mechanical dissection or perforation of the vessel wall. The spot size can be varied over a large range by varying the fiber input coupling, taper length, and numerical aperture. With 480-nm radiation, which is preferentially absorbed by atherosclerotic plaque and thrombus, at 80 μs pulse durations, the device effectively recanalized occluded human peripheral arteries creating a 2-3-mm diameter channel View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Intraocular Nd:YAG laser surgery: laser-tissue interaction, damage range, and reduction of collateral effects

    Publication Year: 1990 , Page(s): 2240 - 2260
    Cited by:  Papers (10)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3304 KB)  

    The damage mechanisms of intraocular Nd:YAG laser surgery and their respective damage ranges were investigated in vitro using bovine cornea specimens as a model tissue. The main damage mechanisms are plasma formation and expansion, emission of acoustic transients, and cavitation with jet formation. When a sequence of laser pulses is applied, the interaction of the acoustic transients with gas bubbles remaining from preceding laser exposures is also important. To distinguish the effects caused by the different physical mechanisms, laser pulses were aimed directly onto the corneal endothelium, through the cornea, and parallel to the cornea at various distances. Simultaneously, the cavitation bubble size was determined. The damage range of the acoustic transients produced by a 4 mJ laser pulse is several millimeters, when they can interact with small gas bubbles attached to the corneal endothelium View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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