NATIONAL INSTITUTE for LASER, PLASMA and RADIATION PHYSICS
  LABORATORY of SOLID-STATE QUANTUM ELECTRONICS

CONTRACT 36 / 06.10.2011; PROGRAMUL 'IDEI', PN-II-ID-PCE-2011-3-0363
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TITLU:                                 Laseri de Tip Ghid de Unda obtinuti prin Tehnica Scrierii Directe cu Pulsuri Laser cu durata de ordinul Femtosecondelor

TITLE:                                 Waveguide Laser Devices Realized by Direct Femtosecond Laser Writing Technique
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FUNDED BY:                        UEFISCDI, Ministry of Education, Research, Youth and Sport, Romania
FINANTARE :                        Unitatea Executiva pentru Finantarea Invatamantului Superior, a Cercetarii, Dezvoltarii şi Inovarii (UEFISCDI), Ministerul Educatiei, Cercetarii, Tineretului si Sportului, Romania
PROJECT MANAGER:           Dr. Nicolaie PAVEL
DIRECTOR DE PROIECT:       Dr. Nicolaie PAVEL
Email:                                   nicolaie.pavel@inflpr.ro
 

PROJECT DURATION:           October 2011 - December 2016
DURATA PROIECTULUI:        Octombrie 2011 - Decembrie 2016

PROJECT LEADER:              National Institute for Laser, Plasma and Radiation Physics, Magurele, Bucharest, Romania
CONDUCATOR PROIECT:
  
  Institutul National de Cercetare-Dezvoltare pentru Fizica Laserilor, Plasmei si Radiatiei, Magurele, Bucuresti, Romania

Contract value:                      1.500.000 lei

Valoare contract:                   1.500.000 lei

The research team:                PAVEL Nicolaie, PhD

Echipa de cercetare:              DASCALU Traian, PhD

                                            ZAMFIRESCU Marian, PhD

                                            SALAMU Gabriela, PhD student

                                            GRIGORE Oana Valeria, PhD student

                                            VOICU Flavius Marian, PhD student

                                            JIPA Florin, PhD student 

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The ability of ultra-short laser pulses to induce permanent changes on the refractive index of solid-state laser media is nowadays attracting much attention because of the unique possibility of three-dimensionally modifying, at the micrometric and sub-micrometric scale, the optical properties of the irradiated media. The interest is of both fundamental and applied point of view. One of the most promising, but also challenging applications of this technique, is the integrated laser active optical circuit fabrication. When femtosecond (fs) pulses are focused inside the bulk media, permanent (micro-) modifications around the focus region are induced; these changes can lead to the creation of buried channel waveguides. On the other hand, material removal can take place if the fs pulses are focused at surface, which could lead to the appearance of a surface channel waveguide close to the ablated volume. A variety of optoelectronic components, such as photonic crystals, diffraction grating, or optical memories can be fabricated by this technique.
One very interesting application of fs direct laser writing is fabrication of buried channel waveguide lasers. For lasers applications, channel waveguides can be used to confine tightly the pump and laser modes and to achieve a high spatial overlap. Furthermore, waveguide confinement can provide lower lasing thresholds and higher pumping efficiencies than are obtainable in bulk laser counterparts. Therefore, due to their robust monolithic nature, waveguide lasers arebecoming potential candidates as efficient laser sources for integrated optics. Nd-lasers are promising active media for waveguide lasers with low threshold, high efficiency, and rather high (watt- or few-watts level) power in continuous wave operation regime.
The main objectives of this project are:
A
. Realization of waveguide lasers by fs direct laser writing;
B
. Demonstration of laser emission in such structures at the fundamental wavelength of emission, as well as in visible spectrum employing multi-functional optical waveguides;
C. Evaluation of various phenomena, like spatial location, magnitude and nature of the micro-structural and refractive index changes, or modification of laser media spectroscopic properties that takes place during and after the process of waveguide writing, the investigations aim being theoretical modeling and explanation of these phenomenon.

1. STAGE I. October - December 2011:
Theoretical substantiation. Experimental conditions for fs-laser beam direct writing in Nd:YAG.
2. STAGE II. December 2012:
Nd-based waveguide lasers obtained by direct writing with fs Ti:sapphire laser in single-crystals gain media.
3. STAGE III. December 2013:
Waveguide lasers based on all-poly-crystalline Nd:YAG ceramics.
4. STAGE IV. December 2014:
Waveguide lasers in Nd-vanadates.
5. STAGE V. December 2015:
Multi-functional optical waveguides. Passively Q-switched waveguide lasers.
6. STAGE V. September 2016:
Multi-functional optical waveguides. The final research report. ___________________________________________________________________________________________________________________________________________________________________________

RESULTS
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1. STAGE I. October - December 2011

Value: 41.000 lei
 Theoretical studies aiming writing of waveguides in Nd-based lasers have been conducted. The characteristics of the laser crystals that will be used in experiments have been determined.
Raportul stiintific pe anul 2011 este disponibil aici: | 2011
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2.  Stage II. December 2012

Value:    570.000 lei
OBJECTIVES
1. Realization of waveguides in Nd:YAG single crystals by direct writing with fs-laser technique.
2. Laser emission at 1.06 si 1.32
Ám under diode pumping at 807 nm.
3. Preliminary experiments aiming wrinting of waveguides in Nd-vanadate laser crystals.
4. Development of a technique for obtaining ceramics Nd:YAG laser media (preliminary experiments).

RESULTS
Waveguides have been inscribed in Nd:YAG single crystals. Various kind, such as two-wall types, and buried cladding depressed structures of rectangular, square, circular or ellipse shapes were realized. The minimal fluence of the Ti:sapphire laser for writing these waveguides was 3.4 J/cm2. The waveguides losses were in the range of  1.1-1.4 dB/cm for the two-wall type waveguides, and from 1.3 to 2.2 dB/cm for the buried cladding depressed wavequides.
Laser emission at 1.06 and 1.34 Ám has been achieved using the pump with diode lasers at 807 nm as follows:
- Laser pulses at 
1.06 Ám (randomly-polarized beam) with energy of 1.8 mJ (overall optical-to-optical efficiency of 20%) were obtained from a buried cladding depressed wavequides with radius of 120 Ám. The same waveguide yielded 0.54 W of continuous-wave power (optical-to-optical efficiency of 14%). A two-wall type waveguide (40 Ám distance between) delivered linearly-polarized pulses with 0.92 mJ energy (optical-to-optical efficiency of 20%);
- The  buried cladding depressed waveguides with radius of 120 Ám emitted laser pulses at 1.32 Ám with energy of 0.4 mJ;
- Laser emission at 946 nm was observed from the same waveguide.
Note: To the best of our knowledge this is the first report on laser emission at 1.32 Ám from Nd:YAG waveguides realized by direct fs-laser writing technique, while the laser performances at both 1.06 and 1.32 Ám wavelengths are the highest obtained under the pump with diode lasers. Further works will consider improvement of the writing technique, especially for the buried depressed cladding waveguides, and realizing of laser emission with increased performances.
Research on realizing Nd:YAG ceramics media by the solid-state sintering method have been conducted.
Raportul stiintific pe anul 2012 este disponibil aici: | 2012
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3. STAGE III. December 2013
Value:    229.808,84 lei
OBJECTIVES
1. Waveguides inscribed by fs-laser writing technique in Nd-vanadate laser crystals.
2. Waveguide lasers in Nd-vanadates under pumping with diode lasers.
3. Writing of waveguides in Nd:YAG ceramic media.
4.
Transparent laser medium realized by ceramics techniques (first stage).
RESULTS
Experiments on writing waveguides in Nd-vanadate laser crystals (Nd:YVO4 si NdGdVO4) have been performed; changes of the refraction index were realized in Nd:YVO4 up to a depth of 400 Ám and in NdGdVO4 up to 200 Ám depth. The minimal fluence of the fs-laser beam that realized changes at the laser crystals surface was 2.0 J/cm2, and this value increased to 3.4-4.0 J/cm2 for depths between 200 and 400 Ám. Experiments on laser emission under diode-laser pumping are in progress. 
● Two-wall type and buried, buried cladding depressed waveguides (of cylindrical shape) were realized in Nd:YAG ceramics.
● Circular, buried depressed-cladding waveguides were realized in a 5.0-mm long, 1.1-at.% Nd:YAG ceramic by direct femtosecond-laser writing using a scheme in which the laser medium is moved on a helical trajectory along its axis and parallel to the writing direction.
Raportul stiintific pe anul 2013 este disponibil aici: | 2013 |
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4. STAGE IV. December 2014
Value:    190.000 lei

OBJECTIVES
1. Transparent laser medium realized by ceramics techniques (continuation).
2. Laser emission from waveguides inscribed in Nd:YAG ceramic media.
3.
Waveguides lasers realized by direct fs-laser writing in Nd:YVO4 and Nd:GdVO4.
RESULTS

 Employing the pump with a fiber-coupled diode laser, laser emission at 1.06 μm and 1.3 μm was achieved in buried waveguides that were inscribed in Nd:YAG ceramic media by fs-laser writing method. A circular cladding waveguide of 100-μm diameter inscribed in a 0.7-at.% Nd:YAG delivered laser pulses at 1.06 μm with 2.8-mJ energy and 0.49-W cw power with overall optical-to-optical efficiency of 0.21 and 0.13, respectively. Laser pulses at 1.3 μm with 1.2-mJ energy were obtained from a 50-μm in diameter circular waveguide.
● Circular cladding waveguides were inscribed by helical movement of the laser medium during the direct fs-laser writing process. Laser pulses with 3.4-mJ energy at 1.06 μm and with 1.2-mJ energy at 1.3 μm under the pump with pulses of 13.1-mJ energy at 807 nm were obtained from a 100-μm diameter circular waveguide that was inscribed in a 1.1-at % Nd:YAG ceramic. The same waveguide yielded 0.48-W cw output power at 1.06 μm. Pulses at 1.06 μm with energy up to 4.1 mJ (overall optical-to-optical efficiency of 0.31) were obtained from a 50-μm diameter circular waveguide. For comparison, a circular waveguide with 100-μm diameter was inscribed by the classical translation method in the same medium. This device outputted laser pulses with maximum energy of 2.2 mJ at 1.06 μm and of 0.82 mJ at 1.3 μm. Optimization of the new inscribing procedure is necessary and should include the choice and correlation of the focusing optics, of the fs-laser pulse energy and of the helical trajectory parameters. These results show that the helical movement of the laser medium during fs-laser writing could be a step forward towards realization of efficient integrated lasers consisting of cladding waveguides pumped by diode lasers.  
● Efficient 1.06 μm and 1.34 μm laser emission from cladding waveguides inscribed by femtosecond-laser writing technique in Nd:YVO4 has been obtained using diode laser pumping. Employing the classical pump at 808 nm (i.e. into the highly-absorbing 4F5/2 level), laser pulses at 1.06 μm with 3.0-mJ energy at optical efficiency of 0.30 and 0.32 slope efficiency have been measured from a circular waveguide of 100-μm diameter that was inscribed in a 0.7-at.% Nd:YVO4 crystal. It has been proved that the pump directly into the 4F3/2 emitting level is an effective method for improving the emission performances of such a laser device. Under the pump at 880 nm the same waveguide yielded laser pulses with increased energy of 3.8 mJ, at higher optical efficiency and slope efficiency of 0.36 and 0.39, respectively. Cw output power of 1.5 W at 1.06 μm was outputted by this waveguide for the pump at 880 nm, in comparison with the 0.9-W output power that was achieved for the 808-nm pump. A similar waveguide inscribed in a 0.5-at.% Nd:YVO4 crystal yielded laser pulses at 1.34 μm with 1.5-mJ energy (at 0.14 optical efficiency) and slope efficiency of 0.19, whereas the pump at 880 nm improved the pulse energy at 1.8 mJ (with optical efficiency of 0.18) and increased the slope to 0.23. The results of this work suggest that the pump with diode lasers directly into the emitting level could be a good solution for realization of efficient waveguide lasers that are inscribed in Nd-vanadate laser media.
Raportul stiintific pe anul 2014 este disponibil aici: | 2014 |
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● Short resume of the results (2011-2014), in English:  | here|
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5. STAGE V. December  2015
Value:    151.386 lei 
(according to Act Aditional nr. 3/2015)
OBJECTIVES

1.
Transparent laser medium realized by ceramics techniques (continuation).
2. Hibrid waveguide lasers:
Passively Q-switched Nd:YAG/Cr4+:YAG lasers.
RESULTS

 Efficient continuous-wave laser emission was obtained using the pump with fiber-coupled diode laser of circular (100-μm diameter), buried depressed cladding waveguides that were inscribed in several Nd:YAG ceramics by fs-laser beam writing method. Output powers of 3.1 W at 1.06 μm and of 1.6 W at 1.3 μm were measured from a 4.5-mm long waveguide that was inscribed in a 1.1-at.% Nd:YAG using a novel, helical-moving of the medium writing technique. The optical-to-optical efficiency was 0.32 at 1.06 μm and 0.17 at 1.3 μm, whereas the slope efficiency was 0.43 and 0.19, respectively.
 Laser operation in Q-switch regime was obtained with Cr4+:YAG SA, the waveguide laser delivering 680 mW average power, in pulses with 19.7-μJ energy at 7-kW pulse peak power. 
 Circular buried depressed-cladding waveguides with were inscribed in composite Nd:YAG/Cr4+:YAG single crystals.
Raportul stiintific pe anul 2015 este disponibil aici: | 2015 |
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6. STAGE VI. December 2016
Value:    317.805,16 lei 
(according to Act Aditional nr. 3/2015)
OBJECTIVES

1.
Transparent laser medium realized by ceramics techniques (final stage).
2. Hibrid waveguide lasers:
Passively Q-switched Nd-vanadates - Cr4+:YAG lasers.
3.
Waveguide laser for generation of green light at 0.53 Ám.
RESULTS

 Efficient laser emission was obtained using the pump with fiber-coupled diode laser of circular (100-μm diameter), buried depressed-cladding waveguides that were inscribed in Nd:YAG ceramics by fs-laser beam writing method. Output powers of 3.1 W at 1.06 mm and of 1.6 W at 1.3 μm were measured from a 4.5-mm long waveguide that was inscribed in a 1.1-at.% Nd:YAG using a novel, helical moving of the medium, writing technique. The optical-to-optical efficiency was 0.32 at 1.06 μm and 0.17 at 1.3 μm, whereas the slope efficiency was 0.43 and 0.19, respectively. Laser operation in Q-switch regime was obtained with Cr4+:YAG SA, the waveguide laser delivering 680 mW average power, pulses with 19.7-μJ energy at 7-kW pulse peak power. The data reported for both cw and Q-switch operation are the highest for such configurations.
 Buried depressed-cladding waveguides with 100-μm diameter have been realized in several Nd:YVO4 laser crystals by fs-laser writing technique. The performances of cw laser emission at 1.06 μm and 1.34 μm were measured under the pump at 808 nm (into the highly-absorbing 4F5/2 level) as well as at 880 nm (directly into the 4F3/2 emitting level) with fiber-coupled diode lasers. The best results were recorded from an waveguide that was inscribed in a 6.9-mm long, 0.5-at.% Nd:YVO4 crystal. Thus, output power of 4.4 W at 1.06 μm was obtained for an absorbed pump power of 9.8 W at 880 nm, corresponding to an overall optical-to-optical efficiency (with respect to the absorbed pump power) of 0.45. The slope efficiency was 0.47. For the emission at 1.34 mm the output power reached 1.7 W with optical-to-optical efficiency of 0.17; the slope efficiency amounted to 0.24. Comparative results are given and discussed for the pump at 808 nm of all the Nd:YVO4 media employed in the experiments.
 The data reported in these works are the highest output powers obtained to date from waveguides inscribed in Nd:YAG and Nd:YVO4 and show the potential of the waveguides inscribed by fs-laser beam technique to realize efficient integrated laser sources pumped by fiber-coupled diode lasers.
● 
Transparent Nd:YAG ceramics (0.5-at.% Nd, 1.0-at.% Nd and 1.5-at.% Nd) were obtained by solid-state reaction method.
Raportul stiintific sintetic este disponibil aici: | 2016 |
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PUBLICATIONS

ARTICLES PUBLISHED IN ISI JOURNALS
10. G. Croitoru (Salamu), F. Jipa, and N. Pavel, “Passive Q-switch laser operation of circular, buried depressed-cladding waveguides realized by direct fs-laser beam writing in Nd:YAG/Cr4+:YAG composite media,” Opt. Mat. Express 7(7), 2496-2504 (2017). (https://doi.org/10.1364/OME.7.002496) [2016 Impact Factor: 2.591]
9. G. Salamu and N. Pavel, “Power scaling from buried depressed-cladding waveguides realized in Nd:YVO4 by femtosecond-laser beam writing," Opt. & Laser Techn. 84, 149-154 (2016). (doi:10.1016/j.optlastec.2016.05.015) [2016 Impact Factor: 2.109]
8. G. Salamu, F. Jipa, M. Zamfirescu, and N. Pavel, “Watt-Level Output Power Operation from Diode-Laser Pumped Circular Buried Depressed-Cladding Waveguides Inscribed in Nd:YAG by Direct Femtosecond-Laser Writing,” IEEE Photonics Journal 8(1), art. 1500209 (2016). (DOI: 10.1109/JPHOT.2015.2512263; http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?punumber=4563994) [2016 Impact Factor: 2.291]
7. N. Pavel, G. Salamu, F. Jipa, and M. Zamfirescu, “Diode-laser pumping into the emitting level for efficient lasing of depressed cladding waveguides realized in Nd:YVO4 by the direct femtosecond-laser writing technique,” Opt. Express 22 (19), 23057-23065 (2014). (http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-19-23057) [2014 Impact Factor: 3.488]
6. N. Pavel, G. Salamu, F. Voicu, F. Jipa, and M. Zamfirescu, “Cladding waveguides realized in Nd:YAG laser media by direct writing with a femtosecond-laser beam,” Proceedings of the Romanian Academy - Series A: Mathematics, Physics, Technical Sciences, Information Science 15 (2), 151-158 (2014). (http://www.academiaromana.ro/sectii2002/proceedings/doc2014-2/07-Pavel.pdf)  [2014 Impact Factor: 1.658]
5. G. Salamu, F. Jipa, M. Zamfirescu, and N. Pavel, “Cladding waveguides realized in Nd:YAG ceramic by direct femtosecond-laser writing with a helical movement technique,” Opt. Material Express 4 (4), 790-797 (2014). (http://www.opticsinfobase.org/ome/abstract.cfm?uri=ome-4-4-790) [2014 Impact Factor: 2.844]
Note:  This paper was included by OSA in the list of “Optical Materials Express’ 15 Most Cited Articles”.
4.
G. Salamu, F. Jipa, M. Zamfirescu, and N. Pavel, “Laser emission from diode-pumped Nd:YAG ceramic waveguide lasers realized by direct femtosecond-laser writing technique,” Opt. Express 22 (5), 5177-5182 (2014). (http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-5-5177)  [2014 Impact Factor: 3.488]
3.  G. Salamu, F. Voicu, N. Pavel, T. Dascalu, F. Jipa, and M. Zamfirescu, “Laser emission in diode-pumped Nd:YAG single-crystal waveguides realized by direct femtosecond-laser writing technique,”
Rom. Reports in Physics 64 (3), 943-953 (2013) (
http://www.rrp.infim.ro/2013_65_3/A29.pdf). [2013 Impact Factor: 1.137]
2.  N. Pavel, G. Salamu, F. Voicu, F. Jipa, M. Zamfirescu, and T. Dascalu, “Efficient laser emission in diode-pumped Nd:YAG buried waveguides realized by direct femtosecond-laser writing,” Laser Physics Letters 10 (9), 095802 (2013) (http://iopscience.iop.org/1612-202X/10/9/095802). [2013 Impact Factor: 2.964]
1. T. Dascalu, G. Salamu, O. Sandu, F. Voicu, and N. Pavel, “Novel laterally pumped by prism laser configuration for compact solid-state lasers,” Laser Physics Letters 10 (5), 055804 (2013) (
http://iopscience.iop.org/1612-202X/10/5/055804/article). [2013 Impact factor: 2.964].
Note: This work was partially (30%) supported from this project.

PATENTS
● T. Dascalu, N. Pavel, G. Salamu, O. Grigore, F. Voicu, M. Dinca, "Sistem laser monolitic, compozit si compact cu livrare simultana a doua fascicule laser / Compact, composite, monolithic laser system with simultaneous emission of two laser beams," Romanian patent, OSIM application number A-100417 / 03.05.2013.
Note: The patent was partially (20%) supported from this project.

PROCEEDINGS
2. G. Salamu, F. Voicu, F. Jipa, M. Zamfirescu, T. Dascalu, and N. Pavel, "Laser emission from diode-pumped Nd:YAG cladding waveguides obtained by direct writing with a femtosecond-laser beam," Proc. SPIE 9135, Laser Sources and Applications II, 91351F (May 1, 2014); doi:10.1117/12.2052250; (http://dx.doi.org/10.1117/12.2052250).
1.
G. Salamu, A. Ionescu, C. Brandus, O. Grigore, N. Pavel and T. Dascalu, "Generation of high-peak power 532-nm green pulses from composite, all-ceramics, passively Q-switched Nd:YAG/Cr4+:YAG laser," Proc. SPIE 8882, ROMOPTO 2012: Tenth Conference on Optics: Micro- to Nanophotonics III, 888206 (June 10, 2013); doi:10.1117/12.2032267 (http://dx.doi.org/10.1117/12.2032267).
Note: This work was partially (50%) founded from this project.

CONFERENCES
17.
G. Croitoru, T. Dascalu, F. Jipa, M. Zamfirescu, N. Pavel, “High-power operation in circular buried depressed-cladding waveguides inscribed in Nd:YAG and Nd:YVO4 by femtosecond-laser beam,” 7th EPS-QEOD EUROPHOTON CONFERENCE, Solid State, Fibre, and Waveguide Coherent Light Sources, 21-26 August, 2016, Vienna, Austria, presentation FWG-4.4 (oral presentation).
16. G. Salamu, N. Pavel, T. Dascalu, F. Jipa, M. Zamfirescu, “Power-scaling from burried depressed-cladding waveguides realized in Nd:YAG and Nd:YVO4 by direct writing with a femtosecond-laser beam,” The 16th International Balkan Workshop on Applied Physics, 7-9 July, 2016, Constanta, Romania; Book of Abstracts, pp. 77-78 (S2 L3, invited presentation).
15. N. Pavel, G. Salamu, F. Voicu, O. Grigore, T. Dascalu, F. Jipa, and M. Zamfirescu, “Depressed-cladding waveguides inscribed in Nd:YAG and Nd:YVO4 by femtosecond-laser writing technique. Realization and laser emission,” ROMOPTO 2015, 11th International Conference on Optics “Micro- to Nano-Photonics IV”, September 1-4, 2015, Bucharest, Romania; presentation I.I.7 (invited presentation).
14. G. Salamu, F. Voicu, F. Jipa, M. Zamfirescu, T. Dascalu, N. Pavel, ”Efficient Laser Emission from Waveguides Inscribed in Nd-doped Media by Femtosecond-Laser Writing Technique,” “Siegman International School on Lasers: 2015”, 02-07 August 2015, Amberg, Germania (poster presentation).
13. G. Salamu, N. Pavel, T. Dascalu, F. Jipa, and M. Zamfirescu, “Diode-Pumped Laser Emission from Depressed Cladding Waveguides Inscribed in Nd-doped Media by Femtosecond Laser Writing Technique,” CLEO Europe - EQEC 2015 Conference, 21-25 June 2015, MŘnich, Germany, presentation CA-P.29 (poster presentation).
12. N. Pavel, G. Salamu, F. Jipa, and M. Zamfirescu, “Efficient Laser Emission under 880-nm Diode-Laser Pumping of Cladding Waveguides Inscribed in Nd:YVO4 by Femtosecond-Laser Writing Technique,“ Advanced Solid State Lasers (ASSL) Congress, 16-21 November 2014, Shanghai, China, presentation ATu2A.26 (poster presentation).
11. G. Salamu, F. Jipa, M. Zamfirescu, F. Voicu, and N. Pavel, “Laser emission from diode-pumped Nd:YAG waveguide lasers realized by femtosecond-writing technique,” 5th International Student Conference on Photonics, Orastie, Romania, 23-26 September 2014; presentation O.02 (oral presentation). Note: This work was awarded with the "Best Oral Presentation - Second Place" diploma at the conference.
10. N. Pavel, G. Salamu, F. Jipa, M. Zamfirescu, F. Voicu, and T. Dascalu, ”Efficient laser emission in diode-pumped Nd:YAG cladding waveguides fabricated by direct writing with a helical movement technique,” 6th EPS-QEOD EUROPHOTON CONFERENCE, Solid State, Fibre, and Waveguide Coherent Light Sources, 24-29 August, 2014, NeuchÔtel, Switzerland, presentation TuP-T2-P-02 (poster presentation); Europhysics Conference Abstract Vol. 38 E; ISBN 2-914771-89-4.
9. N. Pavel, G. Salamu, F. Voicu, T. Dascalu, F. Jipa, and M. Zamfirescu, “Waveguides Fabricated in Nd:YAG by Direct fs-Laser Writing - Realization and Laser Emission under Diode-Laser Pumping,” The 14th International Balkan Workshop on Applied Physics, July 2-4, 2014, Constanta, Romania, presentation S2-L07, Book of Abstracts p. 106 (invited presentation).
8. G. Salamu, F. Jipa, M. Zamfirescu, and N. Pavel, “Laser Emission from Nd:YAG Laser Waveguides Realized by Femtosecond-Laser Writing Techniques,” 2014 Photonics Europe SPIE Conference, 14-17 April 2014, Brussels, Belgium; paper number: 9135-52 (oral presentation) (http://spie.org/EPE/conferencedetails/laser-sources-applications).
7. N. Pavel, G. Salamu, F. Jipa, and M. Zamfirescu, “Laser emission from diode-pumped Nd:YAG waveguides, realized by direct femtosecond-laser writing technique,“ Advanced Solid State Lasers (ASSL) Congress, 27 October - 1 November 2013, Paris, France, presentation ATu2A.6 (oral presentation).
6N. Pavel, G. Salamu, F. Voicu, F. Jipa, and M. Zamfirescu, “Femtosecond-laser inscribed Nd:YAG waveguides. Realization and laser emission,“ LPHYS’13: 22nd International Laser Physics Workshop, Prague, 15-19 July, 2013, presentation 4.1.3 (oral presentation).
5. G. Salamu, F. Voicu, N. Pavel, T. Dascalu, F. Jipa, and M. Zamfirescu, “Diode-pumped laser emission in femtosecond-laser inscribed Nd:YAG waveguides,” International Conference "Modern Laser Applications" Third Edition, INDLAS 2013, 20-24 May 2013, Bran, Romania, presentation O1 (oral presentation).
4. G. Salamu, F. Voicu, F. Jipa, M. Zamfirescu, N. Pavel, “Direct femtosecond laser written waveguides in Nd:YAG,” Micro- to Nano-Photonics III, ROMOPTO 2012, 10th International Conference on Optics, 3-6 September, Bucharest, Romania, presentation II.P. 1 (poster presentation).
3. G. Salamu, A. Ionescu, C. Brandus, O. Sandu, N. Pavel, T. Dascalu, “Generation of high-peak power 532-nm green pulses from passively Q-switched, all-poly-crystalline Nd:YAG/Cr4+:YAG ceramics laser,” Micro- to Nano-Photonics III, ROMOPTO 2012, 10th International Conference on Optics, 3-6 September, Bucharest, Romania, presentation I.P. 5.
; Proc. SPIE 8882, ROMOPTO 2012: Tenth Conference on Optics: Micro- to Nanophotonics III, 888206 (June 10, 2013) (http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1696853).
Note: This work was awarded with the Certificate of Excellence for First Place Student Presentation and Best Poster SPIE Award at the ROMOPTO 2012 conference.
2. N. Pavel, G. Salamu, O. Sandu, A. Ionescu, C. Brandus, F. Voicu, and T. Dascalu, ”Efficient, simultaneous dual-wavelength emission at 1.06 and 1.34 Ám in Nd:GdVO4 laser crystal,” 5th EPS-QEOD EUROPHOTON CONFERENCE, Solid State, Fibre, and Waveguide Coherent Light Sources, 26-31 August, 2012, Stockholm, Sweden, presentation TuP.11 (poster presentation); Europhysics Conference Abstract Vol. 36 E; ISBN 2-914771-778-9.
1. N. Pavel and T. Dascalu, ”High-peak power passively Q-switched Nd:YAG/Cr4+:YAG lasers,” International Student Conference on Photonics 2012, SPIE Student Chapter, 8-11 May 2012, Sinaia, Romania. Book of abstracts, ISSN 2284-9750, p. 79 (invited presentation).

Laboratory of Solid-State Quantum Electronics