Diode-pumped eye sensitive laser at 554.7 nm based on intracavity sum frequency generation

We report for the first time a coherent radiation at 554.7 nm by intracavity sum-frequency generation of 946 nm Nd:YAG laser and 1341 nm Nd:YAP laser. Yellow-green laser is obtained by using a doubly folded cavity, type-II critical phase matching KTP crystal sum-frequency mixing. With total pump power of 36.1 W (17.8 W pump power for 1341 nm Nd:YAP laser and 18.3 W pump power for 946 nm Nd:YAG laser), TEM₀₀ mode yellow-green laser at 554.7 nm of 1.43 W is obtained.     

All-solid-state side-pumped intracavity sum frequency generation yellow laser at 589 nm with the output power of 11.4 W

A laser diode side pump all-solid-state pulse laser at 589 nm with high power and high conversion efficiency and small volume is demonstrated by intracavity sum frequency generation. By optimizing the cavity and adopting etalon techniques, a quasi continuous wave at 589 nm laser source, which has a maximum output power of 11.4 W, a repetition rate of 5 kHz, and a pulse width of 135 ns, is developed. The optical to optical conversion efficiency is up to 6.5% and the power stability is better than 2% in 8 hours.     

Efficient blue laser generation at 473 nm by a BIBO crystal

It is reported that efficient blue laser generation at 473 nm in a BIBO crystal at type-I phase matching direction of (θ,)=(18.3°,90°) performed with a diode-pumped Nd:YAG laser. With incident pump power of 1.6 W, output power of 183 mW at 473 nm has been obtained using a 5.0 mm-long BIBO crystal. The optical conversion efficiency was up to 11.4%. It was found that the intracavity frequency doubling efficiency is about 50% greater than that obtained with a 10 mm-long type-I phase-matching LBO crystal.     

V型腔腔内和频产生3 W连续波589 nm黄光激光器

报道了双Nd：YAG棒串接V型折叠腔腔内KTP和频全固态黄光激光器，得到了3 W连续波589 nm黄光输出.为了提高黄光输出功率，采用了两种手段：一是通过优化腔型设计使得两束基频在腔内达到了最佳的空间重合，二是通过选择合适大小的二极管激光器的抽运功率使得两束基频在腔内达到了最佳的功率配比. 关键词： 全固态激光器 Nd：YAG激光器 黄光 腔内和频     

Self-consistent simulations of quantum cascade laser structures for frequency comb generation

Maxwell–Bloch equations are widely used to model the dynamics due to coherent light-matter interaction in quantum cascade laser (QCL) structures, which plays an essential role especially for the generation of frequency combs and mode-locked pulses. While the modest numerical complexity of the Maxwell–Bloch system allows for a full spatiotemporal treatment, its main disadvantage is the inclusion of dissipation by empirical dephasing rates and electron lifetimes. We present a self-consistent multi-domain approach which couples the Maxwell–Bloch equations to advanced carrier transport simulations based on a density matrix Monte Carlo technique, yielding the scattering and dephasing rates. In this way, the compact spatiotemporal modeling of the carrier-light dynamics by the Maxwell–Bloch system can be combined with the versatility and reliability of self-consistent carrier transport approaches. Simulation results are shown for a QCL-based terahertz frequency comb source, and good agreement with experiment is obtained.     

A frequency-stabilized Yb:KYW femtosecond laser frequency comb and its application to low-phase-noise microwave generation

We present an optically stabilized Yb:KYW fs-laser frequency comb. We use an f–2f nonlinear interferometer to measure the carrier envelope offset frequency (f ₀) and the heterodyne beatnote between the comb and a stable CW laser at 1068 nm to detect fluctuations in the comb repetition rate ( $f_{\mathrm{rep}}$ f rep ). Both of these degrees of freedom of the comb are then controlled using phase-locked loops. As a demonstration of the frequency-stabilized comb, we generate low-phase-noise 10 GHz microwaves through detection of the pulse train on a high bandwidth photodiode. The phase noise of the resulting 10 GHz microwaves was ?99 dBc/Hz at 1 Hz and the corresponding Allen deviation was <2.6 × 10^?15 at 1 s, measured by comparison to an independently stabilized Ti:sapphire frequency comb. This room-temperature, optically based source of microwaves has close-to-carrier phase noise comparable to the very best cryogenic microwave oscillators.     

Diode laser pumped green light source based on intracavity sum frequency generation

We report a continuous-wave (CW) green laser emission by sum-frequency mixing in Nd:GdVO₄ and Nd:YLF crystals. Using type-I critical phase-matching (CPM) LBO crystal, a green laser at 538 nm is obtained by 912 and 1313 nm intracavity sum-frequency mixing. The maximum output power of 185 mW is obtained when an incident pump laser of 18.2 W is used. At the output power level of 185 mW, the output stability is better than 3.3%.     

Coherent bisection of 141 THz using sum frequency generation of 1064 and 709 nm radiation

The frequency interval (141 THz) that exists between 1064 nm radiation and the unusual semiconductor wavelength of 709 nm has been coherently divided by using an optical phase-locked loop to control a slave laser lying at the mean frequency of these two wavelengths. The 709 nm radiation has been generated by a combination of wavelength tuning in an extended cavity and temperature tuning of a ridge-waveguide semiconductor laser with a nominal wavelength of 728 nm. Two nonlinear processes have been used to produce the coherent division: the sum frequency mixing of 1064 and 709 nm radiation to produce 425 nm radiation and the second harmonic generation of 851 nm light to produce the same wavelength radiation.     

Diode-pumped Nd:YVO<Subscript>4</Subscript>-LBO laser at 544 nm based on intracavity sum frequency generation

A dual-wavelength continuous-wave (CW) diode-pumped Nd:YVO₄ laser that generates simultaneous laser action at the wavelengths 914 and 1342 nm is demonstrated. A total dual-wavelength output power of 1.79 W was achieved at the incident pump power of 18.2 W. Furthermore, intracavity sum-frequency mixing at 914 and 1342 nm was then realized in a LBO crystal to reach the yellow-green range. We obtained a total CW output power of 212 mW at 544 nm.     

Theory of sum frequency generation from metal surfaces

zzz (ω₁,ω₂). Four types of metal surfaces are considered: simple metals, alkali metal overlayers, noble metals, and charged metal surfaces. Differences and similarities with respect to second harmonic generation from these surfaces are pointed out. Received: 20 September 1998     

Polarization-multiplexed vibrational sum frequency generation for comprehensive simultaneous characterization of interfaces

We describe a novel three-pulse experimental arrangement for the simultaneous generation and subsequent resolution of all four electric-dipole allowed vibrational sum frequency generation polarization combinations. For noncentrosymmetric and achiral systems, this represents full characterization of all symmetry-allowed elements of the second-order susceptibility, providing a comprehensive intensity level assessment of the system under study. By measuring all relevant signals simultaneously, this approach enables assessment of molecular orientation and structure in dynamic, temporally evolving systems that were previously inaccessible by means of sequentially scanned acquisition of the individual tensor elements.     

Highly efficient electro-optically Q-switched 473 nm blue laser

An external frequency doubling electro-optically Q-switched neodymium-doped yttrium aluminum garnet(Nd:YAG) 473 nm blue laser was demonstrated. With absorbed pump energy of 48 mJ at 100 Hz repetition rate, about 2 mJ of 473 nm blue laser pulse energy was achieved by cascade frequency doubling. The second harmonic conversion efficiency was 64.5%, and overall optical-optical efficiency was 4.2%, respectively. The blue laser pulse width was less than 10 ns, and beam quality factor was less than 2.4.     

Calculation of the stationary generation power of a solid-state raman laser with intracavity second harmonic generation and sum frequency mixing

Analytical equations for the power of second-harmonic stationary generation or sum frequency mixing in a Raman laser with an intracavity nonlinear medium are developed and analyzed as functions of pumping mode and other parameters of the laser system. Parameter relationships providing the maximum output power and conditions for suppression of both stimulated Raman scattering by sum frequency mixing and; consequently, of sum frequency mixing itself are found.     

Efficiency of sum frequency generation by regular domain structures

We theoretically examine generation of sum-frequency radiation in a regular domain structure, taking into account phase changes for all the interacting waves in a dissipative medium. We show that in contrast to the constant-field approximation, in the constant-intensity approximation there is an optimal value for the longitudinal dimension (length) of the domains at which maximum conversion of the signal wave energy to the sum-frequency wave energy occurs. As the pump intensity increases, the optimal domain length decreases. As the losses of the interacting waves increase, both the conversion efficiency and the optimal domain dimensions decrease.     

Continuous-wave laser at 453 nm based on frequency-doubled diode-pumped Nd:ASL crystal

Efficient and compact is generated by intracavity frequency doubling of a diode-pumped Sr_1−x La _{x − y} Nd _y Mg _x Al_{12 − x} O₁₉(Nd:ASL) laser at 906 nm. With 10.3 W of diode pump power and the frequency-doubling crystal LiB₃O₆ (LBO), a maximum output power of 281 mW in the blue spectra] range at 453 nm has been achieved, corresponding to an optical-to-optical conversion efficiency of 2.7%; the output power stability over 4 h is better than 3.8%.     

Multi-peak tunable CW orange laser based on single-pass sum frequency generation in step-chirped MgO: PPLN

We report an all-solid-state tunable CW orange laser based on single-pass sum-frequency generation in step-chirped PPMgO: LN crystal. Two laser sources, a tunable laser (1550 nm) and an ASE laser (1525–1650 nm) are used interchangeably as pumps and mixed with a fixed 975 nm signal laser. Up to 4.3 mW at 597 nm is generated corresponding to 0.87% nonlinear conversion efficiency and the beam quality (M²) value of about 2.5 is measured. The output wavelength can be tuned up to?~?5.66 nm by varying the position of focusing inside the crystal and by temperature, which makes possible the practical application of our device for wavelength selection and diversity in the orange spectral range.     

Efficient yellow beam generation by intracavity sum frequency mixing in DPSS Nd:YVO4 laser

We present our studies on dual wavelength operation using a single Nd:YVO₄ crystal and its intracavity sum frequency generation by considering the influence of the thermal lensing effect on the performance of the laser. A KTP crystal cut for type-II phase matching was used for intracavity sum frequency generation in the cavity at an appropriate location for efficient and stable yellow output power. More than 550 mW of stable CW yellow-orange beam at 593.5 nm with beam quality parameter (M ²) ～4. 3 was obtained. The total pump to yellow beam conversion efficiency was estimated to be 3.83%.     

All-solid-state doubly resonant intracavity frequency sum mixing orange yellow laser with 3.2 W output power at 593.5 nm

A compact and efficient 593.5 nm orange-yellow laser is realized using doubly resonant intracavity sum frequency mixing. Two Nd: YVO₄ crystals are employed as the gain crystals. In two sub-cavities, 1064 nm radiation from one Nd: YVO₄ and 1342 nm radiation from the other Nd: YVO₄ are mixed to generate 593.5 nm orange-yellow laser. In the overlapping of the two cavities, sum frequency mixing is achieved in a type I critical phase matching (CPM) LBO crystal. An output power of 3.2 W at the wavelength of 593.5 nm is obtained with total incident pump power of 38 W. The optical to optical conversion efficiency is up to 8.4% and the stability of the output power is better than 2.48% in 8 h. To the best knowledge, this it the highest watt-level laser at 593.5 nm generated by diode end pump all-solid-state technology.