The Experts below are selected from a list of 127479 Experts worldwide ranked by ideXlab platform
Michal Lipson - One of the best experts on this subject based on the ideXlab platform.
-
Guiding, modulating, and Emitting Light on Silicon - Challenges and opportunities
Journal of Lightwave Technology, 2005Co-Authors: Michal LipsonAbstract:Silicon photonics could enable a chip-scale platform for monolithic integration of optics and microelectronics for applications of optical interconnects in which high data streams are required in a small footprint. This paper discusses mechanisms in silicon photonics for waveguiding, modulating, Light amplification, and emission. These mechanisms, together with recent advances of fabrication techniques, have enabled the demonstration of ultracompact passive and active silicon photonic components with very low loss. TS - RIS
Ronald Sroka - One of the best experts on this subject based on the ideXlab platform.
-
Preliminary evaluation of a novel side-fire diode laser Emitting Light at 940 nm, for the potential treatment of benign prostatic hyperplasia: ex-vivo and in-vivo investigations
BJU International, 2009Co-Authors: Michael Seitz, Thomas Bayer, Robin Ruszat, Derya Tilki, Alexander Bachmann, Christian Gratzke, Boris Schlenker, Christian G. Stief, Ronald Sroka, Oliver ReichAbstract:OBJECTIVES: To evaluate, ex vivo and in vivo, the tissue-removal capacity and coagulation properties of a diode laser Emitting Light at 940 nm, as in the search for potential therapeutic strategies for benign prostatic hyperplasia that cause less morbidity than transurethral resection of the prostate (TURP), various types of lasers have been tested. MATERIALS AND METHODS: A diode laser system (prototype; wavelength 940 nm, Dornier MedTech, Wessling, Germany) was evaluated in an isolated, blood-perfused ex-vivo porcine kidney model at 10-60 W (five kidneys). An in-vivo beagle model was used to investigate the effects on six prostate lobes at a generator output power level of 200 W. After the laser treatment tissue were examined histologically to compare the depth of coagulation and vaporization. RESULTS: With increasing generator output power levels there was an increasing vaporization and coagulation ability for the diode laser at 940 nm in the ex-vivo model. At 60 W the mean (sd) vaporization depth was 1.72 (0.47) mm with a coagulation zone of 9.56 (0.26) mm. In vivo, the diode laser caused rapid ablation with no intraoperative haemorrhage. Histologically, the zone of coagulation had a mean (sd) depth of 4.25 (0.15) mm at 200 W. The tissue removal capacity was estimated at 0.874-1.583 g/min in vivo. CONCLUSIONS: Our findings indicate that diode-laser vaporization at 940 nm is feasible and might be effective for acutely relieving bladder outlet obstruction in an in-vivo setting. Due to its mean coagulation zone of 4.25 mm the diode laser seems to have effective haemostatic properties.
-
comparison of long term results after ho yag and diode laser treatment of hyperplastic inferior nasal turbinates
Lasers in Surgery and Medicine, 2007Co-Authors: Ronald Sroka, P Janda, Tina Killian, F Vaz, Christian S Betz, Andreas LeunigAbstract:Background and Objective Various laser systems have been used to reduce the volume of hyperplastic inferior nasal turbinates during the last 25 years. Although there are many studies reporting the clinical results immediately after laser treatment, there are only a few describing long-term results. Therefore, a clinical study was performed to assess and to compare the long-term outcome of both endonasal Ho:YAG and endonasal diode laser-assisted turbinate surgery. Study Design/Materials and Methods In the first treatment group, a total of 80 patients (allergic rhinitis (46%) and vasomotor rhinitis (54%)) suffering from nasal obstruction due to hyperplastic inferior nasal turbinates were treated by a pulsed Ho:YAG laser Emitting Light at a wavelength of λ = 2,100 nm (pulse energy: 0.8–1.2 J/pulse, repetition rate: 4–8 Hz) under local anesthesia. In the second group, an additional 113 patients (allergic rhinitis (52%) and vasomotor rhinitis (48%)) were treated by means of a continuous wave GaAlAs-diode laser Emitting Light at a wavelength of λ = 940 nm (power: 8–10 W). The treatment time was 3–10 minutes per turbinate and the nasal cavities were left unpacked following the procedure. The study concerning long-term effects was conducted using a standardized questionnaire, allergy test, and rhinomanometry within a follow-up period of 6 month and after 3 years. All patients were refractory to conservative medical treatment prior to laser treatment. Results Three years after laser treatment, a subjective improvement of nasal airflow had been described by the patients in 67.5% after Ho:YAG- and in 74.4% after diode laser treatment. Rhinomanometry revealed a significant improvement of the nasal airflow at both 6 months and 3 years after the laser treatment as compared to the preoperative data. Side effects like nasal dryness and pain were rare (<5%) and occurred only during the first weeks after the intervention. After diode laser treatment, patients showed nasal obstruction due to postoperative edema and nasal crusting during the first 3–4 weeks, whereas patients from the Ho:YAG laser group described these symptoms only for a period of 1–2 weeks. Conclusion Both Ho:YAG- and diode laser treatment, which are performed as an outpatient procedure under local anesthesia, show promising long-term results. It has therefore, developed to become a time and cost-effective treatment modality in endonasal laser surgery at our institution. While short-term differences concerning the healing process after Ho:YAG- compared to diode-laser treatment could be ascertained according to the subjective and objective evaluation, no significant long-term differences between the two investigated groups could be observed. Lasers Surg. Med. © 2007 Wiley-Liss, Inc.
Sergio Brovelli - One of the best experts on this subject based on the ideXlab platform.
-
fully inorganic oxide in oxide ultraviolet nanocrystal Light Emitting devices
Nature Communications, 2012Co-Authors: Sergio Brovelli, Alessandro Lauria, N Chiodini, Roberto Lorenzi, Marco Romagnoli, Alberto PaleariAbstract:Light-Emitting diodes in the form of nanocrystals offer promise for environmental and biomedical diagnostics. Brovelli et al. present a method for realizing mechanically robust and chemically stable nanocrystals Emitting Light in the ultraviolet range.
Yasumasa Kashima - One of the best experts on this subject based on the ideXlab platform.
-
Broad spectrum InGaAsP edge-Emitting Light-Emitting diode using selective-area metal-organic vapor-phase epitaxy
IEEE Photonics Technology Letters, 1998Co-Authors: Yasumasa Kashima, T. MunakataAbstract:We studied the effects of a composition-changing emission region on the emission spectrum using an InGaAsP multiple-quantum-well edge-Emitting Light-Emitting diode (ELED). The ELED was fabricated by selective-area growth using a gradually changing mask stripe width. The spectral half-width exceeded 120 nm at an ambient temperature of 25/spl deg/C, offering a wider spectrum than that of conventional Light-Emitting diodes.
-
InGaAsP multiple quantum well edge-Emitting Light-Emitting diode showing low coherence characteristics using selective-area metalorganic vapor phase epitaxy
Optical Review, 1997Co-Authors: Yasumasa Kashima, T. Munakata, Akio MatobaAbstract:Low coherence multiple-quantum well edge-Emitting Light-Emitting diodes were obtained using selective-area metalorganic vapor-phase epitaxial growth, which utilized growth rate enhancement on an open stripe region between mask stripes. An optical absorption region, which was controlled by selective-area growth, was introduced to suppress optical feedback. At a driving current of 100 mA and an ambient temperature of 25°C, a power of 55 μW was coupled into a single-mode fiber, and a broad spectrum without spectral ripple was observed. Low coherence characteristics and very small temperature dependence were obtained in the temperature range from -40°C to 85°C. The modulation bandwidth was 210 MHz at a bias current of 100 mA.
-
Optical properties of InGaAsP multiple quantum well edge-Emitting Light-Emitting diode
Japanese Journal of Applied Physics, 1994Co-Authors: Yasumasa Kashima, Akio Matoba, Hiroshi Takano, Hisashi Kanie, Taizo IrieAbstract:Effects of the number of wells on the characteristics of a 1.3-µ m edge-Emitting Light-Emitting diode (LED) are investigated. The edge-Emitting LED with 10 quantum wells had the highest optical output power at 100 mA and the lowest temperature coefficient of the optical output power in the temperature range from 10 to 75°C. The experimental result shows that the multiple quantum well structure improves the thermal stability of the optical output power.
Y. -p. Park - One of the best experts on this subject based on the ideXlab platform.
-
Design of an integrated optical pickup with NA of 0.85 for small form factor optical disk drives
Microsystem Technologies, 2005Co-Authors: J. -s. Sohn, T. -s. Song, N. -c. Park, M S Jung, S H Lee, Y. -p. ParkAbstract:We design an integrated optical pickup for small form factor optical disk drives. The specifications of the pickup are compatible with those of the Blu-ray disk (BD) in terms of numerical aperture (NA) of the objective lens, the wavelength of the laser diode, and the thickness of the cover layer. The objective lens unit with NA of 0.85 consists of two aspherical refractive lenses and a diffractive optical element for compensation of the chromatic aberration. Each element of objective lens unit will be fabricated on a wafer as an array type, and the three wafers will be aligned and bonded to form an objective lens array. Therefore, elements of the objective lens unit are designed to have sufficient alignment tolerances for various directions such as de-center and tilt. The optical performances of the objective lens unit are evaluated by simulation against various disturbances such as wavelength change of Emitting Light from laser diode, misalignments, etc. We also design a quarter wave plate, a polarized holographic optical element, and the shape of photodiode integrated circuit array to generate focusing and tracking error signals. The entire height of the pickup including working distance is 2 mm, and the effective pupil diameter of the objective lens unit is less than 1 mm.
-
Design of an integrated optical pickup with NA of 0.85 for small form factor optical disk drives
Microsystem Technologies, 2005Co-Authors: J. -s. Sohn, T. -s. Song, N. -c. Park, M S Jung, S H Lee, Y. -p. ParkAbstract:We design an integrated optical pickup for small form factor optical disk drives. The specifications of the pickup are compatible with those of the Blu-ray disk (BD) in terms of numerical aperture (NA) of the objective lens, the wavelength of the laser diode, and the thickness of the cover layer. The objective lens unit with NA of 0.85 consists of two aspherical refractive lenses and a diffractive optical element for compensation of the chromatic aberration. Each element of objective lens unit will be fabricated on a wafer as an array type, and the three wafers will be aligned and bonded to form an objective lens array. Therefore, elements of the objective lens unit are designed to have sufficient alignment tolerances for various directions such as de-center and tilt. The optical performances of the objective lens unit are evaluated by simulation against various disturbances such as wavelength change of Emitting Light from laser diode, misalignments, etc. We also design a quarter wave plate, a polarized holographic optical element, and the shape of photodiode integrated circuit array to generate focusing and tracking error signals. The entire height of the pickup including working distance is 2 mm, and the effective pupil diameter of the objective lens unit is less than 1 mm.