Colorimetric Phosphate Detection Using Organic DFB Laser-Based Absorption Spectroscopy

A novel compact laser absorption spectrometer is developed for colorimetric detection. We demonstrate the realization of the system as well as example measurements of phosphate in water samples based on the malachite green (MG) method. A phosphate concentration range of to (which corresponds to a molar concentration range of to ) is investigated. This photometer demonstrates the ease of integration of organic distributed feedback (DFB) lasers and their miniaturizability, leading the way toward optofluidic on-chip absorption spectrometers. We constructed an optically pumped organic second-order DFB laser on a transparent substrate, including a transparent encapsulation layer, to have access to both emission directions of the surface-emitting laser. Using the two different surface emission directions of the laser resonator allows monitoring of the emitted light intensity without using additional optical elements. Based on these advances, it is possible to miniaturize the measurement setup of a laser absorption spectrometer and to measure analytes, such as phosphate.

A Review of the High-Power All-Solid-State Single-Frequency Continuous-Wave Laser

High-power all-solid-state single-frequency continuous-wave (CW) lasers have been applied in basic research such as atomic physics, precision measurement, radar and laser guidance, as well as defense and military fields owing to their intrinsic advantages of high beam quality, low noise, narrow linewidth, and high coherence. With the rapid developments of sciences and technologies, the traditional single-frequency lasers cannot meet the development needs of emerging science and technology such as quantum technology, quantum measurement and quantum optics. After long-term efforts and technical research, a novel theory and technology was proposed and developed for improving the whole performance of high-power all-solid-state single-frequency CW lasers, which was implemented by actively introducing a nonlinear optical loss and controlling the stimulated emission rate (SER) in the laser resonator. As a result, the output power, power and frequency stabilities, tuning range and intensity noise of the single-frequency lasers were effectively enhanced.

Seven-rod pumping approach for the most efficient production of TEM00-mode solar laser power by a Fresnel lens

A seven-rod/seven-TEM00 mode beam Fresnel lens solar laser pumping approach is here proposed. The Fresnel lens with 4.0 m2 collection area was used as the primary solar concentrator to pump seven 2.5 mm diameter, 15 mm length Nd:YAG rods within a conical pump cavity through a secondary fused silica aspheric concentrator. Within the pump cavity, solar pump rays not completely absorbed by one of the seven rods were furtherly absorbed by other rods, ensuring hence a high absorption efficiency and avoiding the serious thermal lensing and thermal stress issues associated with classical large rod solar lasers. Seven individual plane-concave large-mode resonators were adopted to enable a good overlap between solar pump mode and TEM00 laser oscillating mode. By using both ZEMAX® and LASCAD® software, the maximum total TEM00 mode solar laser power of 54.65 W was numerically calculated by optimizing the radius parameter of the Fresnel lens, the diameter of the laser rod and the radius of curvature of the laser resonator output mirror. 13.66 W/m2 TEM00 mode solar laser collection efficiency and 1.44% solar power-to-TEM00 mode laser power conversion efficiency were calculated, representing substantial enhancements of 4.66 times and 4.38 times, respectively, as compared to previous experimental records of the TEM00 mode solar laser pumped through a Fresnel lens with 0.785 m2 collection area. The feasibility of TEM00 mode solar laser power delivery by hollow-core photonic crystal fibers was finally studied.

Laser emitter of ultrashort pulses with controllable duration for robotics

This paper presents the analysis and experimental research of an original scheme of the solid-state laser resonator, capable of emitting subnanosecond radiation pulses with controllable duration. For this purpose, it is proposed to use the controllable Michelson interferometer, containing an electro optical phase modulator as a composed output resonator mirror. In this case, the interferometer provides the active resonator mode locking as well as the fast resonator Q-switching mode for effective generation of the output radiation pulses with variable duration.

Controllable Michelson interferometer of refractive type

In some applications of a Michelson interferometer, in particular, when it is used in a laser resonator, the high stability of its phases is necessary. The proposed paper contains the comparison of two interferometer configurations. The first of them uses a classical schematic interferometer, the second one is designed with the use of a refractive schematic one, which is typical of enhanced stability against misalignments and occasional fluctuations of surrounding air. The possibility is discussed of applying the controllable refractive interferometer inside the resonator for generation of ultra short laser pulses.