Continuous-wave Frequency Doubling Research Articles

A high-finesse Fabry–Perot cavity with a frequency-doubled green laser for precision Compton polarimetry at Jefferson Lab

A high-finesse Fabry–Perot cavity with a frequency-doubled continuous wave green laser (532nm) has been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry. The infrared (1064nm) beam from a ytterbium-doped fiber amplifier seeded by a Nd:YAG nonplanar ring oscillator laser is frequency doubled in a single-pass periodically poled MgO:LiNbO3 crystal. The maximum achieved green power at 5W infrared pump power is 1.74W with a total conversion efficiency of 34.8%. The green beam is injected into the optical resonant cavity and enhanced up to 3.7kW with a corresponding enhancement of 3800. The polarization transfer function has been measured in order to determine the intra-cavity circular laser polarization within a measurement uncertainty of 0.7%. The PREx experiment at Jefferson Lab used this system for the first time and achieved 1.0% precision in polarization measurements of an electron beam with energy and current of 1.06GeV and 50μA.

All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 2.17 W output power at 543 nm

An efficient and compact red laser at 458 nm is generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:LuVO4 laser at 916 nm under the condition of suppression the higher gain transition near 1064 nm. With 30 W diode pump power and a frequency doubling crystal LBO, as high as 9.6 W of CW output power at 458 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 32.0% and the output power stability in 8 hours is better than 2.35%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 458 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 916 nm.

All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 9.6 W output power at 458 nm

All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 9.6 W output power at 458 nm

All-Solid-State Continuous-Wave Frequency Doubling Nd:LuVO4/LBO Laser with 2.17 W Output Power at 543 nm

All-Solid-State Continuous-Wave Frequency Doubling Nd:LuVO₄/LBO Laser with 2.17 W Output Power at 543 nm

All-Solid-State Continuous-Wave Frequency Doubling Nd:LuVO4/LBO Laser with 9.6 W Output Power at 458 nm

All-Solid-State Continuous-Wave Frequency Doubling Nd:LuVO₄/LBO Laser with 9.6 W Output Power at 458 nm

All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 9.6 W output power at 672 nm

An efficient and compact red laser at 672 nm is generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:LuVO4 laser at 1344 nm under the condition of suppression the higher gain transition near 1064 nm. With 38 W diode pump power and a frequency doubling crystal LBO, as high as 9.6 W of CW output power at 672 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 25.3% and the output power stability in 8 h is better than 2.38%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 672 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 1344 nm.

All-solid-state continuous-wave frequency doubling Nd:YAG/LBO laser with 8.2 W output power at 660 nm

An efficient and compact red laser at 660 nm is generated by intracavity frequency doubling of continuous wave (CW) laser operation of a diode pumped Nd:YAG laser at 1319 nm under the condition of suppression the higher gain transition near 1064 and 1319 nm under the condition of suppression the higher gain transition near 1064 and 1338 nm. With 40 W diode pump power and a frequency doubling crystal LBO, as high as 8.6 W of CW output power at 660 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 21.5% and the output power stability in 8 h is better than 2.73%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 660 nm generated by intracavity frequency doubling of a diode end pumped Nd:YAG laser at 1319 nm.

All-solid-state continuous-wave frequency doubling Nd:YLF/LBO laser with 2.15 W output power at 526 nm

An efficient and compact green laser at 526 nm generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:YLF laser at 1053 nm under the condition of suppression the high gain transition at 1047 nm. With 19.5 W diode pump power and a frequency doubling crystal LBO, as high as 2.15 W of CW output power at 526 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 11.2% and the output power stability in 8 h is better than 2.87%. To the best of our knowledge, this it the highest watt-level laser at 526 nm generated by intracavity frequency doubling of a diode pumped Nd:YLF laser at 1053 nm.

Second harmonic generation of 2.6W green light with thermoelectrically oxidized undoped congruent lithium niobate crystals below 100°C

We demonstrate that thermoelectric oxidization suppresses unwanted light-induced refractive index changes in undoped congruent periodically poled lithium niobate crystals used for single-pass continuous-wave frequency doubling of 1030nm light. The maximum second harmonic output power shows a strong dependence on the phase matching temperature. For 90°C, a total of 2.6W green light is generated with an efficiency of 22% corresponding to a normalized conversion efficiency of 1.8%∕W.

Sensitive detection and separation of fluorescent derivatives using capillary electrophoresis with laser-induced fluorescence detection with 532 nm Nd:YAG laser

Capillary electrophoresis with laser-induced fluorescence detection (CELIF) is a powerful tool for separation and sensitive determination of fluorescent species. Biologically active compounds, such as amino acids, peptides and proteins may exhibit native fluorescence, which is however often low and/or an expensive laser is required for excitation in UV. Therefore, labelling of the analytes with a fluorescent dye is usually necessary. In this work, a home-built CELIF instrument with diode pumped frequency-doubled continuous wave Nd:YAG excitation laser with feedback power regulation (532 nm) was constructed. The suitability of this type of laser for LIF detection in a separation method was found excellent. A limit of detection (LOD) ( S / N = 3 ) of 2×10 −13 mol/l was achieved with rhodamine B, which is comparable to those obtained using similar instruments with Ar + laser [Y.F. Cheng, N.J. Dovichi, Science 242 (1988) 562, E.S. Yeung et al., J. Chromatogr. 608 (1992) 73]. LOD of a protein derivatized according to modified procedures [M.J. Little et al., Anal. Chim. Acta 339 (1997) 279, A. Chersi et al., Biochim. Biophys. Acta 1336 (1997) 83] was determined. Detection of the derivatives was found to be limited by insufficient reaction recovery at low analyte concentration, chemical noise, separation efficiency and quality of the derivatizing reagent rather than by the detector performance. As a consequence, a huge gap between the detection ability of CELIF instruments and LOD determined in real samples is revealed.

Detection Method of Fatigue Damage in Carbon Steel Using Laser Ultrasonics

Ultrasonic attenuation was measured by the laser ultrasonic technique among the carbon steel specimens which were subjected to five stages of fatigue damage by constant cyclic tensile stress amplitude. Irradiation of a Q-switched laser was used for ultrasonic generation, and a laser interferometer which consists of a frequency-doubled continuous wave laser and a Fabry-Perot etalon was used for detection of ultrasonic vibration on the specimen surface. From the comparison of the broadband ultrasonic waveforms among five stages of fatigue damage, the attenuation coefficient of the longitudinal wave by the intrinsic material attenuation increased progressively with increasing the number of fatigue cycle. Ultrasonic attenuation at 2.5, 5.0, 7.5 and 10.0MHz were also calculated by Fourier transformation in order to compare the decay of the longitudinal wave among these frequency components. From the results, ultrasonic attenuation increased as the number of fatigue cycle increased, in both broadband and narrowband frequency components. Therefore, the measurement of broadband and narrowband ultrasonic wave obtained by the laser ultrasonic technique would be effective as the detection method of fatigue damage in nuclear power plant components.

Detection Method of Fatigue Damage in Carbon Steel Using Laser Ultrasonics.

Ultrasonic attenuation was measured by the laser ultrasonic technique among the carbon steel specimens which were subjected to five stages of fatigue damage by constant cyclic tensile stress amplitude. Irradiation of a Q-switched laser was used for ultrasonic generation, and a laser interferometer which consists of a frequency-doubled continuous wave laser and a Fabry-Perot etalon was used for detection of ultrasonic vibration on the specimen surface. From the comparison of the broadband ultrasonic waveforms among five stages of fatigue damage, the attenuation coefficient of the longitudinal wave by the intrinsic material attenuation increased progressively with increasing the number of fatigue cycle. Ultrasonic attenuation at 2.5, 5.0, 7.5 and 10.0MHz were also calculated by Fourier transformation in order to compare the decay of the longitudinal wave among these frequency components. From the results, ultrasonic attenuation increased as the number of fatigue cycle increased, in both broadband and narrowband frequency components. Therefore, the measurement of broadband and narrowband ultrasonic wave obtained by the laser ultrasonic technique would be effective as the detection method of fatigue damage in nuclear power plant components.

New vibrational analysis of the 1B2(1Δu) state of CS2

Sub-Doppler excitation spectra of CS2 in the spectral range of 29 600–32 800 cm−1 (V-system) are measured with a frequency doubled continuous wave (cw) single-mode dye laser. The ultraviolet (UV) radiation is generated in an external enhancement cavity. The average output power is about 5 mW, which is sufficient to resolve weak rotational lines in the excitation spectra of hot bands from the (0,22,0) level of the ground state. This increased the number of measured transitions with K>0 considerably. The low temperature achieved by adiabatic cooling of CS2 seeded in a supersonic argon beam simplifies the spectrum and allows an exact assignment of the rotational lines. Based on new ab initio calculations, a revised electronic state and vibrational assignment of the bands were necessary and will be presented. From this vibrational analysis the geometry, the position of the barrier to linearity, and the rotational constants of the CS2 molecule in the V 1B2(1Δu) state have been determined, revising former results. A statistical analysis of the positions of all measured bands shows a pure Poissonian nearest level distribution indicating no correlation between neighboring vibrational levels nor long-range interactions.

Efficient continuous-wave frequency doubling of a tunable CO_2 laser in AgGaSe_2

Second-harmonic output at 4.6-5.5 mum of the order of 6 mW with a 0.12% external conversion efficiency has been obtained by pumping a AgGaSe(2) crystal with a low-power cw CO(2) laser. The surface damage threshold of AgGaSe(2) for cw radiation was found to be inside the limit of 33-45 kW/cm(2) in the 9.2-10.8-mum wavelength region. Another important limitation of the pump power connected with a thermal lensing effect in crystal was determined experimentally. A comparison was made of AgGaSe(2) and ZnGeP(2) crystals as materials suitable for the efficient generation of the second harmonic of cw CO(2) laser radiation.

82% Efficient continuous-wave frequency doubling of 106 μm with a monolithic MgO:LiNbO_3 resonator: errata

We describe a frequency-doubling monolithic standing-wave resonator made of MgO:LiNbO(3) with dielectric mirror coatings for impedance matching near 100 mW input power and near-optimum nonlinear coupling. An external conversion efficiency of 82% has been achieved.

82% Efficient continuous-wave frequency doubling of 106 μm with a monolithic MgO:LiNbO_3 resonator

We describe a frequency-doubling monolithic standing-wave resonator made of MgO:LiNbO(3) with dielectric mirror coatings for impedance matching near 100 mW input power and near-optimum nonlinear coupling. An external conversion efficiency of 82% has been achieved.

Direct measurement of the picosecond decay time of the J aggregate of pseudoisocyanine iodide using an optically compressed frequency-doubled continuous wave Nd—YAG laser and a synchronously operating streak camera

Using the shorter than 4 ps pulses at 532 nm from a frequency-doubled optically compressed continuous wave Nd—YAG laser, in conjunction with a synchronously operating streak camera, the flourescence decay of the J aggregates of 1,1′-diethyl-2,2′-cyanine (pseudoisocyanine) iodide has been measured with picosecond resolution to be 24 ps. The power and concentration dependence are also described.