Valentin Petrov | VUZF - Academia.edu (original) (raw)

Papers by Valentin Petrov

2007 Conference on Lasers and Electro-Optics (CLEO), 2007

Composite Yb:KY(WO 4) 2 grown on KY(WO 4) 2 substrates by segmented growth showed highly efficien... more Composite Yb:KY(WO 4) 2 grown on KY(WO 4) 2 substrates by segmented growth showed highly efficient continuous-wave laser operation with slope efficiencies as high as 80% and 375 mW output power was demonstrated.

2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006

We demonstrate output powers exceeding 4 W with continuous-wave, diode-pumped Yb:TVO 4 (T=Y, Gd, ... more We demonstrate output powers exceeding 4 W with continuous-wave, diode-pumped Yb:TVO 4 (T=Y, Gd, and Lu) lasers operated at room temperature. The three orthovanadate hosts are compared in longitudinal and thin-disk pump geometries.

Optics Express, 2015

We report on the first Tm-doped double tungstate microchip laser Q-switched with graphene using a... more We report on the first Tm-doped double tungstate microchip laser Q-switched with graphene using a Tm:KLu(W04)2 crystal cut along the TV g dielectric axis. This laser generates a maximum average output power of 310 mW with a slope efficiency of 13%. At a repetition rate of 190 kHz the shortest pulses with 285 ns duration and 1.6 pj energy are achieved.

Conference on Lasers and Electro-Optics 2010, 2010

ABSTRACT Passive mode locking of the self-frequency doubling Yb:Ca4YO(BO3)3pumped by a two-sectio... more ABSTRACT Passive mode locking of the self-frequency doubling Yb:Ca4YO(BO3)3pumped by a two-section distributed Bragg-reflector tapered-diode-laser is demonstrated. Pulses as short as 49 fs at 1050 nm are achieved for the E//Z polarization.

Lasers, Sources, and Related Photonic Devices, 2012

ABSTRACT

SPIE Proceedings, 2014

ABSTRACT CdSiP2 (CSP) is a very promising nonlinear crystal for the mid-IR spectral range with a ... more ABSTRACT CdSiP2 (CSP) is a very promising nonlinear crystal for the mid-IR spectral range with a nonlinear coefficient slightly larger than that of ZnGeP2 (ZGP). In contrast to ZGP, CSP is phase-matchable and can be employed in 1.064-μm pumped optical parametric oscillators (OPOs) without two-photon absorption. Although low damage resistivity has been reported in such initial OPO tests of CSP, no reliable data on the damage-threshold of uncoated CSP exists. We compare in this work the damage resistivity of uncoated CSP with ZGP at two wavelengths, 2.09 μm (1 kHz, 21 ns) and 1.064 μm (100 Hz, 8 ns).

Optics Letters, 2015

We report on a continuous-wave Ho:KLuWO 4 2 (KLuW) microchip laser with a record slope efficiency... more We report on a continuous-wave Ho:KLuWO 4 2 (KLuW) microchip laser with a record slope efficiency of 84%, the highest value among the holmium inband-pumped lasers, delivering 201 mW output power at 2105 nm. The Ho laser operating at room temperature on the 5 I 8 → 5 I 7 transition is in-band-pumped by a diode-pumped Tm:KLuW microchip laser at 1946 nm. Ho:KLuW laser operation at 2061 and 2079 nm is also demonstrated with a maximum slope efficiency of 79%. The microchip laser generates an almost diffraction-limited output beam with a Gaussian profile and a M 2 < 1.1. The laser performance of the N g-cut Ho:KLuW crystal is very similar for pump light polarizations ‖N m and N p. The positive thermal lens plays a key role in the laser mode stabilization and proper mode-matching. The latter, together with the low quantum defect under in-band-pumping (∼0.08), is responsible for the extraordinary high slope efficiency.

SPIE Proceedings, 2013

ABSTRACT We investigated optical damage (surface and bulk) in wide band-gap (absorption edge belo... more ABSTRACT We investigated optical damage (surface and bulk) in wide band-gap (absorption edge below 532 nm) sulphide and selenide nonlinear crystals that can be used in 1064-nm pumped optical parametric oscillators (OPOs) for generation of idler pulses above 4 μm without two-photon absorption losses at the pump wavelength. The optical damage has been characterized at the pump wavelength for different repetition rates. Surface damage has been studied for uncoated and antireflection-coated (mainly with a single layer for pump and signal wavelengths) samples. Optical damage inside the OPO has a lower threshold and represents at present the principal limitation for the achievable output. It is related to peak and not to average intensities and in many of the studied crystals bulk damage in the form of scattering centers occurs before surface damage. Such bulk damage formation is faster at higher repetition rate. Lower repetition rates increase the lifetime of the crystal but do not solve the problem. In the most successful nonlinear crystal (both in terms of output energy and average power), orange-phase HgGa2S4, the safe pump intensity in extracavity measurements is below 100 MW/cm2 which corresponds to less than 1 J/cm2 for the 8 ns pulse duration (both values peak on-axis). In the OPO, however, peak on-axis fluence should not exceed 0.3 J/cm2 limited by the formation of bulk scattering centers. The damage resistivity of yellow-phase HgGa2S4 or Cd-doped HgGa2S4 is higher and of the almost colorless CdGa2S4 it is roughly two times higher but the latter has no sufficient birefringence for phase-matching.

Optical Materials Express, 2013

ABSTRACT We employ LiInSe2 nonlinear crystal for difference-frequency generation between signal a... more ABSTRACT We employ LiInSe2 nonlinear crystal for difference-frequency generation between signal and idler of a synchronously pumped femtosecond optical parametric oscillator at 80 MHz achieving continuous tuning from 4 µm (16.7 mW) to 11.5 µm (2.3 mW).

Nonlinear Optics, 2011

We have grown single crystals of PbIn 6 Te 10 , with clear transparency from 3 to 20 µm, and show... more We have grown single crystals of PbIn 6 Te 10 , with clear transparency from 3 to 20 µm, and showed that it possesses sufficient birefringence for phase-matching of three-wave parametric interactions and a nonlinear coefficient of 51 pm/V.

Solid State Lasers XX: Technology and Devices, 2011

Passive mode-locking of Nd-lasers operating on the 4F3/2 --&amp;amp;amp;amp;amp;amp;amp;amp;a... more Passive mode-locking of Nd-lasers operating on the 4F3/2 --&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 4I13/2 transition is problematic for semiconductor saturable absorber mirrors (SESAMs) not only because of difficulties in their fabrication process but also in relation to the achievable parameters and damage resistivity. We investigate an alternative approach based on second-order nonlinearity inside the laser cavity which utilizes negative chi(2)-lens formation in a SHG

Lasers, Sources, and Related Photonic Devices, 2012

ABSTRACT A mode-locked Tm:Lu2O3 laser delivering pulses as short as 175 fs at 2070 nm is demonstr... more ABSTRACT A mode-locked Tm:Lu2O3 laser delivering pulses as short as 175 fs at 2070 nm is demonstrated. The self-starting oscillator is mode-locked by a single-walled carbon nanotube-based saturable absorber and operates at 88 MHz.

CLEO: 2013, 2013

ABSTRACT HgGa2S4 is employed in a 1064-nm pumped optical parametric oscillator, to generate ~5-ns... more ABSTRACT HgGa2S4 is employed in a 1064-nm pumped optical parametric oscillator, to generate ~5-ns long idler pulses near 4 µm with energies as high as 6.1 mJ and average power of 610 mW at 100 Hz.

Optics Letters, 2007

High-power continuous-wave laser operation was demonstrated with Yb: KLu͑WO 4 ͒ 2 crystals cut al... more High-power continuous-wave laser operation was demonstrated with Yb: KLu͑WO 4 ͒ 2 crystals cut along the N p , N m , and N g principal optical axes, achieving a nearly equal slope efficiency of 79%-80% in the absence of thermal effects. The N g-cut crystal proved to be the most advantageous for power scaling as well as efficient pumping. A maximum output power of 11.0 W was produced from a 2 mm thick uncoated N g-cut crystal in a ϳ7 mm long plano-concave resonator end pumped by a fiber-coupled diode; the corresponding optical-to-optical efficiency was 68%.

Optics Letters, 2012

Low-threshold, efficient optical parametric generation at ∼6100 nm is demonstrated using CdSiP 2 ... more Low-threshold, efficient optical parametric generation at ∼6100 nm is demonstrated using CdSiP 2 nonlinear crystal at 1 to 10 kHz repetition rates with relatively long 500 ps pump pulses at 1064 nm. Maximum single pulse energy of 8.7 μJ and average power of 79 mW are achieved for the idler. Seeding at the signal wavelength is employed using a distributed feedback laser diode, which enables approximately tenfold narrowing of the idler bandwidth down to less than 1 nm.

Optics Express, 2011

Self-starting, steady-state χ (2)-lens mode-locking of a 1.34-μm diode-pumped Nd:YVO 4 laser usin... more Self-starting, steady-state χ (2)-lens mode-locking of a 1.34-μm diode-pumped Nd:YVO 4 laser using intracavity second harmonic generation in PPMgSLT is demonstrated. Pulses as short as 3.6 ps with an average output power of ~1 W are obtained at a repetition rate of 120 MHz.

Optics Express, 2007

Macrodefect-free single crystals of Yb-doped KGd(PO 3) 4 , a noncentrosymmetric laser host which ... more Macrodefect-free single crystals of Yb-doped KGd(PO 3) 4 , a noncentrosymmetric laser host which possesses second-order nonlinear susceptibility, were grown using the top seeded solution growth slowcooling (TSSG-SC) technique, reaching a maximum ytterbium concentration in the crystal of ≈3.2×10 20 at/cm 3. In order to evaluate the potential for self-frequency doubling, the dispersion of the refractive indices of KGd(PO 3) 4 was studied and Sellmeier equations were constructed which are valid in the visible and near-infrared. The Stark splitting of the two electronic states of ytterbium was determined from absorption and emission measurements at room and low temperatures, and this allowed to compute the emission cross sections at room temperature. The fluorescence decay time is quite long, 1.22±0.01 ms. Laser generation in the 1 µm range is demonstrated with this new Yb host for the first time. Although the maximum output power achieved, of the order of 100 mW, was limited by the available crystal size and doping level, the more than 55% slope efficiency obtained with this first sample is rather promising for the future.

2007 Conference on Lasers and Electro-Optics (CLEO), 2007

Composite Yb:KY(WO 4) 2 grown on KY(WO 4) 2 substrates by segmented growth showed highly efficien... more Composite Yb:KY(WO 4) 2 grown on KY(WO 4) 2 substrates by segmented growth showed highly efficient continuous-wave laser operation with slope efficiencies as high as 80% and 375 mW output power was demonstrated.

2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006

We demonstrate output powers exceeding 4 W with continuous-wave, diode-pumped Yb:TVO 4 (T=Y, Gd, ... more We demonstrate output powers exceeding 4 W with continuous-wave, diode-pumped Yb:TVO 4 (T=Y, Gd, and Lu) lasers operated at room temperature. The three orthovanadate hosts are compared in longitudinal and thin-disk pump geometries.

Optics Express, 2015

We report on the first Tm-doped double tungstate microchip laser Q-switched with graphene using a... more We report on the first Tm-doped double tungstate microchip laser Q-switched with graphene using a Tm:KLu(W04)2 crystal cut along the TV g dielectric axis. This laser generates a maximum average output power of 310 mW with a slope efficiency of 13%. At a repetition rate of 190 kHz the shortest pulses with 285 ns duration and 1.6 pj energy are achieved.

Conference on Lasers and Electro-Optics 2010, 2010

ABSTRACT Passive mode locking of the self-frequency doubling Yb:Ca4YO(BO3)3pumped by a two-sectio... more ABSTRACT Passive mode locking of the self-frequency doubling Yb:Ca4YO(BO3)3pumped by a two-section distributed Bragg-reflector tapered-diode-laser is demonstrated. Pulses as short as 49 fs at 1050 nm are achieved for the E//Z polarization.

Lasers, Sources, and Related Photonic Devices, 2012

ABSTRACT

SPIE Proceedings, 2014

ABSTRACT CdSiP2 (CSP) is a very promising nonlinear crystal for the mid-IR spectral range with a ... more ABSTRACT CdSiP2 (CSP) is a very promising nonlinear crystal for the mid-IR spectral range with a nonlinear coefficient slightly larger than that of ZnGeP2 (ZGP). In contrast to ZGP, CSP is phase-matchable and can be employed in 1.064-μm pumped optical parametric oscillators (OPOs) without two-photon absorption. Although low damage resistivity has been reported in such initial OPO tests of CSP, no reliable data on the damage-threshold of uncoated CSP exists. We compare in this work the damage resistivity of uncoated CSP with ZGP at two wavelengths, 2.09 μm (1 kHz, 21 ns) and 1.064 μm (100 Hz, 8 ns).

Optics Letters, 2015

We report on a continuous-wave Ho:KLuWO 4 2 (KLuW) microchip laser with a record slope efficiency... more We report on a continuous-wave Ho:KLuWO 4 2 (KLuW) microchip laser with a record slope efficiency of 84%, the highest value among the holmium inband-pumped lasers, delivering 201 mW output power at 2105 nm. The Ho laser operating at room temperature on the 5 I 8 → 5 I 7 transition is in-band-pumped by a diode-pumped Tm:KLuW microchip laser at 1946 nm. Ho:KLuW laser operation at 2061 and 2079 nm is also demonstrated with a maximum slope efficiency of 79%. The microchip laser generates an almost diffraction-limited output beam with a Gaussian profile and a M 2 < 1.1. The laser performance of the N g-cut Ho:KLuW crystal is very similar for pump light polarizations ‖N m and N p. The positive thermal lens plays a key role in the laser mode stabilization and proper mode-matching. The latter, together with the low quantum defect under in-band-pumping (∼0.08), is responsible for the extraordinary high slope efficiency.

SPIE Proceedings, 2013

ABSTRACT We investigated optical damage (surface and bulk) in wide band-gap (absorption edge belo... more ABSTRACT We investigated optical damage (surface and bulk) in wide band-gap (absorption edge below 532 nm) sulphide and selenide nonlinear crystals that can be used in 1064-nm pumped optical parametric oscillators (OPOs) for generation of idler pulses above 4 μm without two-photon absorption losses at the pump wavelength. The optical damage has been characterized at the pump wavelength for different repetition rates. Surface damage has been studied for uncoated and antireflection-coated (mainly with a single layer for pump and signal wavelengths) samples. Optical damage inside the OPO has a lower threshold and represents at present the principal limitation for the achievable output. It is related to peak and not to average intensities and in many of the studied crystals bulk damage in the form of scattering centers occurs before surface damage. Such bulk damage formation is faster at higher repetition rate. Lower repetition rates increase the lifetime of the crystal but do not solve the problem. In the most successful nonlinear crystal (both in terms of output energy and average power), orange-phase HgGa2S4, the safe pump intensity in extracavity measurements is below 100 MW/cm2 which corresponds to less than 1 J/cm2 for the 8 ns pulse duration (both values peak on-axis). In the OPO, however, peak on-axis fluence should not exceed 0.3 J/cm2 limited by the formation of bulk scattering centers. The damage resistivity of yellow-phase HgGa2S4 or Cd-doped HgGa2S4 is higher and of the almost colorless CdGa2S4 it is roughly two times higher but the latter has no sufficient birefringence for phase-matching.

Optical Materials Express, 2013

ABSTRACT We employ LiInSe2 nonlinear crystal for difference-frequency generation between signal a... more ABSTRACT We employ LiInSe2 nonlinear crystal for difference-frequency generation between signal and idler of a synchronously pumped femtosecond optical parametric oscillator at 80 MHz achieving continuous tuning from 4 µm (16.7 mW) to 11.5 µm (2.3 mW).

Nonlinear Optics, 2011

We have grown single crystals of PbIn 6 Te 10 , with clear transparency from 3 to 20 µm, and show... more We have grown single crystals of PbIn 6 Te 10 , with clear transparency from 3 to 20 µm, and showed that it possesses sufficient birefringence for phase-matching of three-wave parametric interactions and a nonlinear coefficient of 51 pm/V.

Solid State Lasers XX: Technology and Devices, 2011

Passive mode-locking of Nd-lasers operating on the 4F3/2 --&amp;amp;amp;amp;amp;amp;amp;amp;a... more Passive mode-locking of Nd-lasers operating on the 4F3/2 --&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 4I13/2 transition is problematic for semiconductor saturable absorber mirrors (SESAMs) not only because of difficulties in their fabrication process but also in relation to the achievable parameters and damage resistivity. We investigate an alternative approach based on second-order nonlinearity inside the laser cavity which utilizes negative chi(2)-lens formation in a SHG

Lasers, Sources, and Related Photonic Devices, 2012

ABSTRACT A mode-locked Tm:Lu2O3 laser delivering pulses as short as 175 fs at 2070 nm is demonstr... more ABSTRACT A mode-locked Tm:Lu2O3 laser delivering pulses as short as 175 fs at 2070 nm is demonstrated. The self-starting oscillator is mode-locked by a single-walled carbon nanotube-based saturable absorber and operates at 88 MHz.

CLEO: 2013, 2013

ABSTRACT HgGa2S4 is employed in a 1064-nm pumped optical parametric oscillator, to generate ~5-ns... more ABSTRACT HgGa2S4 is employed in a 1064-nm pumped optical parametric oscillator, to generate ~5-ns long idler pulses near 4 µm with energies as high as 6.1 mJ and average power of 610 mW at 100 Hz.

Optics Letters, 2007

High-power continuous-wave laser operation was demonstrated with Yb: KLu͑WO 4 ͒ 2 crystals cut al... more High-power continuous-wave laser operation was demonstrated with Yb: KLu͑WO 4 ͒ 2 crystals cut along the N p , N m , and N g principal optical axes, achieving a nearly equal slope efficiency of 79%-80% in the absence of thermal effects. The N g-cut crystal proved to be the most advantageous for power scaling as well as efficient pumping. A maximum output power of 11.0 W was produced from a 2 mm thick uncoated N g-cut crystal in a ϳ7 mm long plano-concave resonator end pumped by a fiber-coupled diode; the corresponding optical-to-optical efficiency was 68%.

Optics Letters, 2012

Low-threshold, efficient optical parametric generation at ∼6100 nm is demonstrated using CdSiP 2 ... more Low-threshold, efficient optical parametric generation at ∼6100 nm is demonstrated using CdSiP 2 nonlinear crystal at 1 to 10 kHz repetition rates with relatively long 500 ps pump pulses at 1064 nm. Maximum single pulse energy of 8.7 μJ and average power of 79 mW are achieved for the idler. Seeding at the signal wavelength is employed using a distributed feedback laser diode, which enables approximately tenfold narrowing of the idler bandwidth down to less than 1 nm.

Optics Express, 2011

Self-starting, steady-state χ (2)-lens mode-locking of a 1.34-μm diode-pumped Nd:YVO 4 laser usin... more Self-starting, steady-state χ (2)-lens mode-locking of a 1.34-μm diode-pumped Nd:YVO 4 laser using intracavity second harmonic generation in PPMgSLT is demonstrated. Pulses as short as 3.6 ps with an average output power of ~1 W are obtained at a repetition rate of 120 MHz.

Optics Express, 2007

Macrodefect-free single crystals of Yb-doped KGd(PO 3) 4 , a noncentrosymmetric laser host which ... more Macrodefect-free single crystals of Yb-doped KGd(PO 3) 4 , a noncentrosymmetric laser host which possesses second-order nonlinear susceptibility, were grown using the top seeded solution growth slowcooling (TSSG-SC) technique, reaching a maximum ytterbium concentration in the crystal of ≈3.2×10 20 at/cm 3. In order to evaluate the potential for self-frequency doubling, the dispersion of the refractive indices of KGd(PO 3) 4 was studied and Sellmeier equations were constructed which are valid in the visible and near-infrared. The Stark splitting of the two electronic states of ytterbium was determined from absorption and emission measurements at room and low temperatures, and this allowed to compute the emission cross sections at room temperature. The fluorescence decay time is quite long, 1.22±0.01 ms. Laser generation in the 1 µm range is demonstrated with this new Yb host for the first time. Although the maximum output power achieved, of the order of 100 mW, was limited by the available crystal size and doping level, the more than 55% slope efficiency obtained with this first sample is rather promising for the future.