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At least 163 records · Page 9Linked to original sources
PubMed2005

Erbium: yttrium-aluminum-garnet laser application in stapedotomy.

OBJECTIVE: To assess clinical safety and efficacy of the erbium: yttrium-aluminum-garnet (Er:YAG) laser in the stapes surgery; to define and optimize parameters that render the procedure safe for the inner ear. STUDY DESIGN: Retrospective study. MATERIAL AND METHODS: A microscope-integrated Er:YAG laser stapedotomy was performed on 29 patients and a conventional stapedotomy on 41 patients. An early (within 1 to 3 days after stapes surgery) and late (at least 6 weeks) pure-tone bone-conduction threshold audiogram was obtained. RESULTS: No statistically significant differences were found by Student's t test over all measured frequencies between pre- and postoperative bone-conduction thresholds in each group. There was no statistically significant difference for all frequencies between early (3 days) and late postoperative mean bone-conduction thresholds. CONCLUSIONS: The results of our preliminary clinical study showed that erbium laser poses no risk to inner ear function. However, the lack of standardization obliges further investigation to establish safe clinical parameters of the Er:YAG laser.

Adult↗
PubMed1994

Erbium:YAG laser photothermal retinal ablation in enucleated rabbit eyes.

The erbium:YAG laser has been shown to produce precise tissue ablation because of the high water absorption of the 2.94-microns wave-length emitted by this laser. We used an experimental system to create lesions of various depths in the surface of the rabbit retina in enucleated eyes in vitro to examine the potential application to maneuvers such as retinotomy and the removal of epiretinal membranes in vitrectomy. With an air/retinal interface, single pulses produced discrete craters in the retinal surface with a depth proportional to fluence, ranging from 30 microns for a pulse of 1.3 J/cm2 to a full-thickness retinotomy at 3.9 J/cm2. An adjacent zone of coagulated tissue ranging in size from 15 to 40 microns was noted. Multiple pulses had an additive effect. With a fluid/retinal interface, 20 pulses of 3.6 J/cm2 produced a full-thickness retinotomy, with an adjacent zone of damaged tissue up to 1 mm, caused by effects of volatilization of intervening fluid. The erbium:YAG laser may have a role in vitreoretinal surgery.

Animals↗
PubMed1997

Photovaporization rate and profile of an erbium-chromium:YAG laser in the fundamental mode.

PURPOSE: To evaluate the ablation characteristics of an experimental erbium:YAG (Er:YAG) laser and assess whether it delivers sufficient output for performing photorefractive keratectomy. SETTING: Department of Ophthalmology, Virchow-Clinics, Humboldt University, Berlin, Germany. METHODS: An experimental Er:YAG laser, the erbium-chromium:YAG, running in fundamental mode was used to evaluate the energy profile. Measurements obtained using a joulemeter were compared to the ablation profiles of cadaver pig eyes. The pig eyes were treated with different fluences (mean 0.8 to 2.9 J/cm2) and, after histological preparation, were examined using light and scanning electron microscopy. RESULTS: Measurements with the joulemeter and in the cadaver pig eyes showed a Gaussian-curved profile of energy (ablation). In the current setting, the diameter of ablation was 3.5 mm. Histological examination showed a homogeneous profile of ablation with minor thermal damage. CONCLUSION: The Er:YAG laser running in the fundamental mode allows homogeneous ablation of corneal tissue. The Er:YAG laser is easier to handle technically than the excimer laser and has none of the potential risks of ultraviolet light.

Animals↗
PubMed2002

Micro-tensile bond strength of two adhesives to Erbium:YAG-lased vs. bur-cut enamel and dentin.

The purpose of the study was to assess the hypotheses that laser irradiation is equally effective for bonding as traditional acid-etch procedures, and that tooth substrate prepared either by Erbium:YAG laser or diamond bur is equally receptive to adhesive procedures. Buccal/oral enamel and mid-coronal dentin were laser-irradiated using an Erbium:YAG laser. A total-etch adhesive (OptiBond FL) applied with and without prior acid-etching and a self-etch adhesive (Clearfil SE Bond) were employed to bond the composite. The micro-tensile bond strength (microTBS) was determined after 24 h of storage in water. Failure patterns were analysed using a stereo-microscope, and samples were processed for Field-emission Scanning Electron Microscopy (Fe-SEM) evaluation. Unbonded, lased enamel and dentin surfaces were evaluated using Fe-SEM as well. The total-etch adhesive bonded significantly less effectively to lased than to bur-cut enamel/dentin. Laser 'conditioning' was clearly less effective than acid-etching. Moreover, acid etching lased enamel and dentin significantly improved the microTBS of OptiBond FL. The self-etch adhesive performed equally to lased as to bur-cut enamel, but significantly less effectively to lased than to bur-cut dentin. It is concluded that cavities prepared by laser appear less receptive to adhesive procedures than conventional bur-cut cavities.

Acid Etching, Dental↗
PubMed2003

Upconversion fluorescence imaging of erbium-doped fluoride glass particles by apertureless SNOM.

We have imaged fluorescent erbium-doped fluoride glass particles by apertureless scanning near-field optical microscopy. The optical excitation has been performed at lambda = 780 nm whereas fluorescence emission has been collected around lambda = 550 nm. This process, called upconversion by energy transfer, involves two erbium ions and is not linear. Besides an improvement of the lateral resolution, we have observed on some particles that the fluorescence is not homogeneously distributed, but is rather localized in some zones brighter than others. By making tip approach curves, we have also observed that the amount of fluorescence intensity scattered by the tip is increasing when the tip is approaching the sample surface.

Journal Article↗
PubMed1990

Vascular tissue ablation by an erbium-YAG laser: a fiber-transmittable pulsed laser in the infrared range.

Vascular tissue ablation by an erbium:YAG laser of 2,940 nm was tested in-vitro with the application of increasing energies from 20 to 80 mJ per pulse. Effective ablation of normal vascular tissue, lipomatous atheromas and calcified plaques was achieved. Penetration depth was considerably diminished in the presence of calcifications. The lasered craters showed smooth surfaces and were regularly shaped. The solid state erbium:YAG, which is transmittable by fluoride fibers, offers theoretical advantages for laser angioplasty.

Aortic Diseases↗
PubMed2006

Laser cooling without repumping: a magneto-optical trap for erbium atoms.

We report on a novel mechanism that allows for strong laser cooling of atoms that do not have a closed cycling transition. This mechanism is observed in a magneto-optical trap (MOT) for erbium, an atom with a very complex energy level structure with multiple pathways for optical-pumping losses. We observe surprisingly high trap populations of over 10(6) atoms and densities of over 10(11) atoms cm(-3), despite the many potential loss channels. A model based on recycling of metastable and ground state atoms held in the quadrupole magnetic field of the trap explains the high trap population, and agrees well with time-dependent measurements of MOT fluorescence. The demonstration of trapping of a rare-earth atom such as erbium opens a wide range of new possibilities for practical applications and fundamental studies with cold atoms.

Journal Article↗
PubMed2004

Permanent repigmentation of piebaldism by erbium:YAG laser and autologous cultured epidermis.

BACKGROUND: Several surgical techniques have been proposed for the treatment of piebaldism. These procedures, however, are poorly suited for the treatment of large leucodermal lesions, can cause scars and require multiple donor sites. Recently, it has been reported that autologous cultured epidermis induces scarless repigmentation of large vitiligo lesions, using a single small donor site. OBJECTIVES: To induce permanent repigmentation of large achromic lesions in patients suffering from piebaldism by means of autologous cultured epidermal grafts using a rapid, simple and non-invasive surgical procedure. METHODS: Six patients with piebaldism were enrolled in this study. Achromic epidermis was removed by means of appropriately set erbium:YAG laser and autologous cultured epidermal grafts were applied on to the recipient bed. Melanocyte content was evaluated by 3,4-dihydroxyphenylalanine reaction. The percentage of repigmentation was calculated using a semiautomatic image analysis system. RESULTS: Autologous cultured epidermis, bearing a controlled number of melanocytes, induced repigmentation of all piebald lesions. The mean percentage repigmentation was 95.45% (2791.5 cm2 repigmented/2924.2 cm2 transplanted). CONCLUSIONS: Autologous cultured epidermal grafts induce permanent and complete repigmentation of piebald lesions, in the absence of scars. Erbium:YAG laser surgery is a rapid and precise tool for disepithelialization, hence allowing treatment of large piebald lesions during a single surgical operation.

Adolescent↗
PubMed2006

Erbium:YAG laser-assisted preparation of a combined dermal/full thickness sandwich skin graft.

BACKGROUND: Skin grafting is a common procedure to close defects after tumor resection. However, delicate areas such as the heel or the sole of the foot can be closed with a specially designed graft as described in this article. OBJECTIVE: To describe a surgical technique by means of erbium:YAG laser-assisted preparation of a combined dermal/full-thickness sandwich skin graft that facilitates the closure of defects, especially at mechanically stressed anatomic sites. METHODS: Tumor defects on the sole of the foot of 28 patients were closed with a new dermal/full-thickness sandwich skin graft. To obtain this special graft, half of a full-thickness skin graft twice the size of the wound defect was deepithelialized with an erbium:YAG laser. After complete defatting of the transplant, the deepithelialized part was folded beneath the full-thickness part (upside down) resulting in a sandwich graft, enabling contact of the papillary dermis with the wound surface. Graft results were graded as excellent when more than 75%, good if 50-75%, fair if 25-50%, and poor if less than 25% of the transplant healed. RESULTS: Results were graded as excellent in 32%, good in 54%, fair in 11%, and poor in 3% of the patients. Total graft loss was experienced in 1 of 28 patients. Complications such as bulky margins or infection were encountered in 14% of the patients. CONCLUSION: The laser-assisted preparation of the combined dermal/full-thickness sandwich skin graft is a new technique that facilitates the closure of defects in delicate anatomic locations with high mechanical stress like the plantar sole.

Aged↗
PubMed2002

Suppression of self-pulsing behavior in erbium-doped fiber lasers with a semiconductor optical amplifier.

We experimentally demonstrate that the stability of cw and mode-locked erbium-doped fiber ring lasers can be improved significantly with a semiconductor optical amplifier (SOA) inside the cavity. The fast saturable gain of the SOA suppresses significantly the self-pulsing that is due to ion pairs in the erbium-doped fiber, which acts as a saturable absorber. A linear stabilization analysis of the laser system agrees with our experimental results.

Journal Article↗
PubMed2005

Polarized erbium-doped superfluorescent fiber source utilizing double-pass backward configuration.

An erbium-doped superfluorescent fiber source utilizing a double-pass backward configuration is analyzed when a polarizer is inserted into an erbium-doped fiber to obtain polarized output light. Such a polarized configuration is simulated and experimentally confirmed to have the following characteristics: high polarization power conversion efficiency, pump-power-independent mean-wavelength operation, and low sensitivity to polarizer insertion loss.

Journal Article↗
PubMed2005

Tight packaging of erbium-doped waveguide amplifiers.

A numerical model for erbium-doped waveguide amplifiers (EDWAs) containing bent waveguides was developed. The model uses rate-propagation equations and takes into account bend-induced losses in the waveguide with a varying radius of curvature. It is applied to the design of tightly packed erbium-doped waveguide amplifiers under two constraints: minimization of the area required to obtain a predetermined gain and maximization of the gain available from a given area. Numerical calculations based on realistic waveguide parameters demonstrate the possibility of fabricating high-gain, small-size EDWAs. Simple design rules, based on geometric formulas and consideration of bend losses, are given and compared with the results of numerical calculations.

Journal Article↗
PubMed2005

Characterization of a multiwavelength Brillouin-erbium fiber laser based on a linear cavity configuration.

We experimentally demonstrate a simple method for generating a multiwavelength Brillouin comb by utilizing a linear cavity of hybrid Brillouin-erbium fiber lasers (BEFLs). The optimization of Brillouin pump wavelength, power, and erbium gain played a significant role in determining the maximum number of Brillouin Stokes signals generated. Simultaneous and stable multiple-wavelength laser output of 22 lines with 10.88-GHz channel spacing has been obtained with good flatness. Various parameters such as 980-nm pump power, Brillouin pump wavelength, and Brillouin pump power that affect the performance of a multiwavelength BEFL system have been investigated. An analysis of the tuning range of the system is presented.

Journal Article↗
PubMed2003

Amplification and compression of ultrashort fundamental solitons in an erbium-doped nonlinear amplifying fiber loop mirror.

A nonlinear amplifying loop mirror constructed from erbium-doped fiber is proposed for simultaneous amplification and compression of ultrashort fundamental solitons. Numerical simulations show that, unlike conventional erbium-doped fiber amplifiers in which nonlinear effects lead to serious degradation of pulse quality, the proposed device performs efficient high-quality amplification and compression of ultrashort fundamental solitons while it almost completely preserves the soliton nature of the input pulses. Moreover, the performance of the device is insensitive to small variations in the loop length and in the power-splitting ratio of the coupler.

Journal Article↗
PubMed2003

5-W repetitively Q-switched Er:LuAG laser resonantly pumped by an erbium fiber laser.

We report a high-average-power, near-diffraction-limited Er:LuAG laser generating 5 W of power at 1.648 microm in either cw or repetitively Q-switched operation. When the laser is Q switched at 9 kHz, we measure 0.52 mJ/pulse. The laser is end pumped by a 20-W erbium fiber laser and achieves >30% optical conversion efficiency and >40% incident slope efficiency. This is, to our knowledge, the highest performance (average power and conversion efficiency) obtained from a bulk solid-state erbium laser.

Journal Article↗
PubMed2004

Concentration-induced nonuniform power in tunable erbium-doped fiber lasers.

We report, for the first time to our knowledge, the presence of concentration-induced nonuniform power in tunable erbium-doped fiber lasers. A theoretical model is proposed with pair-induced quenching taken into account. We obtain good agreement between numerical and experimental results of a high-concentration erbium-doped fiber ring laser with a large tuning range of over 100 nm. These findings are useful for the design of lasers with doped fibers.

Journal Article↗
PubMed2005

Erbium partitioning in a heavily doped transparent glass ceramic.

An erbium-doped transparent glass ceramic, consisting of LaF3 nanocrystallites with a characteristic length of approximately 20 nm embedded in an aluminosilicate glass matrix and exhibiting infrared-to-green up-conversion, has been studied. The degree of erbium partitioning into the nanocrystallite phase was found using energy transfer coefficients determined from bulk Er3+:LaF3 samples. This transparent glass ceramic sample was found to have a partitioning fraction of 19 +/- 5%.

Journal Article↗
PubMed1998

Erbium: YAG laser--an improved periorbital resurfacing device.

Erbium: yttrium aluminum garnet lasers are highly absorbed by water within the skin. This has reduced thermal effects associated with carbon dioxide laser skin resurfacing, such as prolonged postoperative erythema, delayed healing, scarring, and pigmentation. The erbium: yttrium aluminum garnet is an ideal treatment for mild to moderate periorbital rhytids.

Dermatologic Surgical Procedures↗