In this work the authors intend to present a new approximate technique of solving the characteristic (eigenvalue) equation for a step index fiber optic near cut-off. To illustrate this new method, there are presented (and demonstrated) two particular forms, corresponding to the case v equals 0 (TE0m and TM0m modes). Solutions of these equations are compared with other solutions suggested by Marcuse and--also--it is analyzed the accuracy of our results compared with the general solution of the characteristic equation.
{"title":"Approximate solutions of the eigenvalue equation near cutoff for TE0mand TM0m modes for a step index fiber optic: new forms and considerations","authors":"C. Schiopu, P. Schiopu","doi":"10.1117/12.312686","DOIUrl":"https://doi.org/10.1117/12.312686","url":null,"abstract":"In this work the authors intend to present a new approximate technique of solving the characteristic (eigenvalue) equation for a step index fiber optic near cut-off. To illustrate this new method, there are presented (and demonstrated) two particular forms, corresponding to the case v equals 0 (TE0m and TM0m modes). Solutions of these equations are compared with other solutions suggested by Marcuse and--also--it is analyzed the accuracy of our results compared with the general solution of the characteristic equation.","PeriodicalId":383583,"journal":{"name":"ROMOPTO International Conference on Micro- to Nano- Photonics III","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115056543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The optical properties of layered materials of a fractal quasiperiodic structure are reviewed considering both the case of wavelength smaller than the thickness of the thinner layer and the reverse case in which the whole structure is much smaller than the wavelength.
{"title":"Optical properties of quasi-periodic (self-similar) structures","authors":"M. Bertolotti, C. Sibilia","doi":"10.1117/12.312774","DOIUrl":"https://doi.org/10.1117/12.312774","url":null,"abstract":"The optical properties of layered materials of a fractal quasiperiodic structure are reviewed considering both the case of wavelength smaller than the thickness of the thinner layer and the reverse case in which the whole structure is much smaller than the wavelength.","PeriodicalId":383583,"journal":{"name":"ROMOPTO International Conference on Micro- to Nano- Photonics III","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115074965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper summarizes the peculiarities of the nonlinear interaction of short laser pulses with the noncrystalline semiconductors (chalcogenide glasses, a-Si:H), showing that noncrystalline semiconductors (NS) are an interesting material for high speed optoelectronics. The physical mechanisms, which can contribute to the nonlinear light absorption in NS under pulsed excitation, are reviewed.
{"title":"Nonlinear optical properties of noncrystalline semiconductors","authors":"Valentin N. Ciumash","doi":"10.1117/12.312789","DOIUrl":"https://doi.org/10.1117/12.312789","url":null,"abstract":"The paper summarizes the peculiarities of the nonlinear interaction of short laser pulses with the noncrystalline semiconductors (chalcogenide glasses, a-Si:H), showing that noncrystalline semiconductors (NS) are an interesting material for high speed optoelectronics. The physical mechanisms, which can contribute to the nonlinear light absorption in NS under pulsed excitation, are reviewed.","PeriodicalId":383583,"journal":{"name":"ROMOPTO International Conference on Micro- to Nano- Photonics III","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128671625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Calian, M. Ursache, C. Sarpe-Tudoran, M. Socaciu
A numerical method for simulating realistic problems of mode coupling in optical transmission systems is described. The conclusion concerning waveguided propagation of the electromagnetic field in complex structures, selective mode excitation and the power transfer may become an important factor in designing and connecting devices used in optical signal processing. The numerical method is based on an extension of the `Orthogonal Collocation Method' to the case of coupled systems of differential equations with an infinite range of independent variables.
{"title":"Computing coupling coefficients in transmission systems","authors":"V. Calian, M. Ursache, C. Sarpe-Tudoran, M. Socaciu","doi":"10.1117/12.312766","DOIUrl":"https://doi.org/10.1117/12.312766","url":null,"abstract":"A numerical method for simulating realistic problems of mode coupling in optical transmission systems is described. The conclusion concerning waveguided propagation of the electromagnetic field in complex structures, selective mode excitation and the power transfer may become an important factor in designing and connecting devices used in optical signal processing. The numerical method is based on an extension of the `Orthogonal Collocation Method' to the case of coupled systems of differential equations with an infinite range of independent variables.","PeriodicalId":383583,"journal":{"name":"ROMOPTO International Conference on Micro- to Nano- Photonics III","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127765369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The processes involved in the melting and solidification of powders have been studied, in order to obtain 3D pieces. The experiments have been performed with a CW Nd:YAG laser, but the Q-switched regime has been also used. Measurements about compacting rate for different parameters (scanning speed, thickness of layer) and a comparison between the two regimes have been made.
{"title":"Compacting of metallic powder by using Nd:YAG laser","authors":"A. Marian, Dan Buca, T. Dascălu, M. Poterasu","doi":"10.1117/12.312763","DOIUrl":"https://doi.org/10.1117/12.312763","url":null,"abstract":"The processes involved in the melting and solidification of powders have been studied, in order to obtain 3D pieces. The experiments have been performed with a CW Nd:YAG laser, but the Q-switched regime has been also used. Measurements about compacting rate for different parameters (scanning speed, thickness of layer) and a comparison between the two regimes have been made.","PeriodicalId":383583,"journal":{"name":"ROMOPTO International Conference on Micro- to Nano- Photonics III","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124604059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Stratan, C. Fenic, R. Dabu, N. Herisanu, C. Luculescu, D. Sporea, G. Dumitru, G. Iordache
We have developed a laser-diode pump system for continuous-wave end-pumping of Nd:YAG lasers. The pump system includes a pair of 1 W diode-arrays mounted in coaxial enclosures, a driver unit and the pump optics. The array wavelength was temperature tuned to achieve the maximum absorption of the pump radiation in the Nd:YAG crystal. The characteristics of the pump system are presented and the pump-beam profile is investigated.
{"title":"Performance of a pump system for diode-pumped lasers","authors":"A. Stratan, C. Fenic, R. Dabu, N. Herisanu, C. Luculescu, D. Sporea, G. Dumitru, G. Iordache","doi":"10.1117/12.312681","DOIUrl":"https://doi.org/10.1117/12.312681","url":null,"abstract":"We have developed a laser-diode pump system for continuous-wave end-pumping of Nd:YAG lasers. The pump system includes a pair of 1 W diode-arrays mounted in coaxial enclosures, a driver unit and the pump optics. The array wavelength was temperature tuned to achieve the maximum absorption of the pump radiation in the Nd:YAG crystal. The characteristics of the pump system are presented and the pump-beam profile is investigated.","PeriodicalId":383583,"journal":{"name":"ROMOPTO International Conference on Micro- to Nano- Photonics III","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126178249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents an experimental study on the behavior of piezoceramics type PZT, having a high compliance, and their application for an optoelectronic micropositioner device with piezoceramic transducer. The piezoelectric ceramics are crystallite conglomerate ferroelectrics materials with random orienting. In the laboratory we have realized PZT ceramics with various additions (Ni, Bi, Mn), presenting high compliance, for optoelectronic micropositioning device in micrometry displacements. The experimental transducers, realized like stacks of 30 divided by 35 pieces of PZT thin disks, supplied with 0 divided by 1000 V voltages, have produced 0 divided by 15 micrometers displacements.
{"title":"Optoelectronic micropositioning device with a piezoceramic transducer","authors":"I. Chilibon, M. Robu","doi":"10.1117/12.312680","DOIUrl":"https://doi.org/10.1117/12.312680","url":null,"abstract":"This paper presents an experimental study on the behavior of piezoceramics type PZT, having a high compliance, and their application for an optoelectronic micropositioner device with piezoceramic transducer. The piezoelectric ceramics are crystallite conglomerate ferroelectrics materials with random orienting. In the laboratory we have realized PZT ceramics with various additions (Ni, Bi, Mn), presenting high compliance, for optoelectronic micropositioning device in micrometry displacements. The experimental transducers, realized like stacks of 30 divided by 35 pieces of PZT thin disks, supplied with 0 divided by 1000 V voltages, have produced 0 divided by 15 micrometers displacements.","PeriodicalId":383583,"journal":{"name":"ROMOPTO International Conference on Micro- to Nano- Photonics III","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126723262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Antipa, V. Moldoveanu, N. Rusca, I. Bruckner, Mihaela Vlăiculescu, E. Ionescu, V. Vasiliu
Low power laser (LPL) use in the treatment of arthrosic rheumatism is well known. From a total number of 280 patients with symptomatic spondylosis we finally selected 66, with changes of the EEG color mapping. These investigation was done before and after treatment in order to obtain an objective method to appreciate these results. The patients were splitted in laser group (36 patients treated with HeNe and IR diode LPL) and control group (30 patients treated with placebo laser). The results indicate a significant improvement of the symptoms at 77% of the patients from laser group as compared with 33% favorable results at the placebo laser. The EEG mapping improved at 58% patients from laser group as compared with 20% at the control group.
{"title":"Value of low-power lasers in the treatment of symptomatic spondilosis","authors":"C. Antipa, V. Moldoveanu, N. Rusca, I. Bruckner, Mihaela Vlăiculescu, E. Ionescu, V. Vasiliu","doi":"10.1117/12.312830","DOIUrl":"https://doi.org/10.1117/12.312830","url":null,"abstract":"Low power laser (LPL) use in the treatment of arthrosic rheumatism is well known. From a total number of 280 patients with symptomatic spondylosis we finally selected 66, with changes of the EEG color mapping. These investigation was done before and after treatment in order to obtain an objective method to appreciate these results. The patients were splitted in laser group (36 patients treated with HeNe and IR diode LPL) and control group (30 patients treated with placebo laser). The results indicate a significant improvement of the symptoms at 77% of the patients from laser group as compared with 33% favorable results at the placebo laser. The EEG mapping improved at 58% patients from laser group as compared with 20% at the control group.","PeriodicalId":383583,"journal":{"name":"ROMOPTO International Conference on Micro- to Nano- Photonics III","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132055902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We apply the quasiadiabatic approximation for the femtosecond pulse propagation in a collection of excitons in the case of weak interaction between the optical pulse and the semiconductor medium. Using the semiconductor Maxwell-Bloch equations beyond the slowly varying envelope approximation we show that the dynamics of femtosecond pulse propagation is described by the modified Korteweg-de Vries equation. Bright solitons superimposed on a continuous wave background are found and their stability against low amplitude perturbations is investigated. Possible experiments in semiconductor systems such as GaAs/AlGaAs are discussed.
{"title":"Novel femtosecond optical solitons in weakly excited semiconductors","authors":"D. Mihalache, I. Mel'nikov, N. Panoiu","doi":"10.1117/12.312775","DOIUrl":"https://doi.org/10.1117/12.312775","url":null,"abstract":"We apply the quasiadiabatic approximation for the femtosecond pulse propagation in a collection of excitons in the case of weak interaction between the optical pulse and the semiconductor medium. Using the semiconductor Maxwell-Bloch equations beyond the slowly varying envelope approximation we show that the dynamics of femtosecond pulse propagation is described by the modified Korteweg-de Vries equation. Bright solitons superimposed on a continuous wave background are found and their stability against low amplitude perturbations is investigated. Possible experiments in semiconductor systems such as GaAs/AlGaAs are discussed.","PeriodicalId":383583,"journal":{"name":"ROMOPTO International Conference on Micro- to Nano- Photonics III","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134071318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The algorithm presented in this paper proposes a way to find the optimum glasses that assure a better correction for optical apparatus with the human eye as a final receiver. The model (Ne, v1, v2), based on the Buchdahl formula, gives an approximation error for the refraction index less than 5(DOT)10-5 for visible domain. We introduced in the merit function used for optimizing the optical system an operand that describes the existence of an optical glass. This operand was defined so that the obtained value for Ne, v1 and v2 can be closed to some values for a real glass. A definition for this operand is obtained using the PNe, Pv1, Pv2, probabilities of existence for a glass with a certain parameter Ne, v1 or v2. Another possibility to define this operand is to describe the volume occupied by the optical glass in (Ne, v1, v2) space with some elliptical functions. The probabilities and the elliptical functions were found after an analysis for all optical glasses listed in the Schott catalogues was made.
{"title":"New method for automatic optimization of glass combination in optical systems working in the visible range","authors":"D. Ralea, R. Mărginean, Marinica Marzu","doi":"10.1117/12.312728","DOIUrl":"https://doi.org/10.1117/12.312728","url":null,"abstract":"The algorithm presented in this paper proposes a way to find the optimum glasses that assure a better correction for optical apparatus with the human eye as a final receiver. The model (Ne, v1, v2), based on the Buchdahl formula, gives an approximation error for the refraction index less than 5(DOT)10-5 for visible domain. We introduced in the merit function used for optimizing the optical system an operand that describes the existence of an optical glass. This operand was defined so that the obtained value for Ne, v1 and v2 can be closed to some values for a real glass. A definition for this operand is obtained using the PNe, Pv1, Pv2, probabilities of existence for a glass with a certain parameter Ne, v1 or v2. Another possibility to define this operand is to describe the volume occupied by the optical glass in (Ne, v1, v2) space with some elliptical functions. The probabilities and the elliptical functions were found after an analysis for all optical glasses listed in the Schott catalogues was made.","PeriodicalId":383583,"journal":{"name":"ROMOPTO International Conference on Micro- to Nano- Photonics III","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134337892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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