We report the research results on Solid-State Laser System for Terahertz Radiation Generation. Terahertz radiation
generation is based on a double longitudinal mode laser with a single linear cavity and laser amplifiers. The laser is LD
pumped CW Nd:YVO4 laser with a single linear cavity. The double longitudinal mode laser beam makes it very
convenient to control their propagation for Terahertz radiation generation. The relative intensities of the modes and the
frequency difference between the modes can be adjusted for high efficiency generating THz radiation with required
frequency. The CW laser beam was first amplified by a LD end-pumped Nd:YVO<sub>4</sub> amplifier, then it was changed into
pulsed beam by an LN electro-optical modulator. The pulsed laser beam was amplified by other four Nd:YVO4
amplifiers pumped by three 6W LDs and a 35W optical fiber coupled LDA, respectively, and became strong enough
and was projected into an organic nonlinear optical crystal DAST to generate THz radiation with narrow linewidth and
stable frequency. By this method a new kind of THz wave source can be developed. It is smaller in size, high efficient
and no any adjustment is needed in applications. The paper reports the experimental setup and results in details.
High-speed flier velocity measurement is one of the key technologies in investigating collision sites on the surfaces of spacecraft structures impacted by high-speed space debris. We have designed and constructed an optoelectronic system to accurately determine the average velocity of a flier impacting on a spacecraft structure. The system is based on two parallel laser screens, which are crossed by the fliers before impact. This system utilizes scattered light as the start and the end signal to measure the time of flight between the two screens. A wideband optical sensor has been designed and evaluated, and an electronic circuit is used to accurately record the time of flight and calculate the velocity. Experimental results show this system is adequate to measure the velocity of a flier larger than 100 µm, in the range from 0.1 to 10 km/s, with accuracy better than 1.3%, and with low cost, simplicity, and high reliability.
A multi-end-pumped nonplanar ring laser with a two-mirror resonator has been demonstrated. Two important parameters of the beam loops are described, and simulation diagrams of the beam loops are shown. Using an output coupler with a fan-shaped distribution in reflectivity, multi-end-pumped operation with the output beam from a single point has been achieved, and the experimental results show that the laser could be multi-end-pumped to reduce thermal effects and multiply the fracture limit of the laser crystal.
Self-triggering pulsed laser ranging, a novel pulsed laser ranging method, can ease the trade-off between ranging precision and measurement speed in the traditional laser ranging technique. Theoretical analysis and system design for time-of-flight measurement, which determines both the ranging precision and the measuring speed of self-triggering pulsed laser ranging, is performed. An experiment on self-triggering pulsed laser ranging is reported, in which submillimeter (better than 0.5 mm) precision is achieved over a 20-m range.
The optical characteristic of Nd:YAG ceramic was introduced, and a LD pumped high efficiency Nd:YAG ceramic laser was demonstrated. The laser threshold is 48mW with <i>R</i>=97% output coupler. With 2W LD pumping, 812mW CW laser output at 1064 nm has been obtained, and the corresponding optical-to-optical efficiency is as high as 45.6%. A LD pumped high efficiency high repetition rate A-O Q-switched Nd:YAG ceramic laser was also demonstrated. With a 2W LD pumping, the obtained narrowest pulse width, highest peak power and highest energy per pulse are 16.4ns, 2.46kW and 40.5μJ, respectively. The experimental study about the influence of repetition rate on the performance of A-O Q-switched pulse laser was emphasized, and the experiment results were analyzed and discussed.
A new type of <i>Q</i>-switched pulsed lasers (CPQL, Controllable Passively Q-switched Laser) is presented. The laser is composite of a passively Q-switched laser with a saturable absorber and a controlling LD with a focus system. The performance of the laser output pulses, including the pulse energy, pulse width, pulse generation moment and repetition frequency, can be actively controlled by the operator with the controlling LD. The new type laser is discussed theoretically and the experiment results are present. Compare to the ordinary <i>Q</i>-switched laser, including passively Q-switched lasers and actively Q-switched lasers, CPQL’s have higher performance and will find important applications in many fields.
By combining the techniques of AO (acousto-optic) Q-switching and EO (electro-optic) cavity-dumping, a new type of diode-pumped nanosecond pulsed laser was proposed for the first time. The Q- switched pulses at 1.06micrometers with a peak power of 5.02kW and a pulse width 3.1ns pumped a 1W laser diode on the Nd:YVO<SUB>4</SUB> microchip at the 1kHz repetition rate were obtained. The temporal characteristics of the pulses were analyzed numerically. The experiment results are shown to be in good agreement with theoretical predictions.
In the paper we describe a completely new type of diode-pumped solid-state ring traveling-wave laser with two mirrors. Compared with traditional single-frequency laser, mode-locked laser and high power laser, this kind of novel ring traveling- wave lasers is more compact, reliable and affordable.
We report the implementation of a low loss core-cladding waveguide structure of an a-axis Nd:MgO:LiNbO<SUB>3</SUB> single crystal fiber and the demonstration of a frequency-doubled laser made from such a cladded crystal fiber. The laser-heated pedestal grown a-axis single crystal fiber, which has an elliptical cross sectional area of about 200 micrometer X 150 micrometer, was further treated with a Mg-ion indiffusion process. An electron probe microanalysis was used to measure the Mg-ion concentration distribution of the Mg diffused layer. After a number of trials, the diffusion parameters suitable for forming a core-cladding waveguide structure have been obtained. The optical and structural properties of the cladded crystal fibers were also characterized. A diode pumped external cavity frequency doubled laser has been made from the cladded crystal fiber. At room temperature, CW green laser output with a power of 10 (mu) W at the wavelength of 0.532 micrometer has been obtained. The origins of the relatively low frequency-doubled conversion efficiency will also be discussed.
The electro-optic characteristics of the KTP crystal are analyzed in detail and Q-switched operation of a diode-laser- pumped Nd:YVO<SUB>4</SUB> laser is reported using an intracavity KTP crystal. The KTP crystal was used as both an electro-optic Q- switcher and a frequency-doubling crystal in type II phase matching for generating pulsed green beams. Compared with the conventional frequency-doubling and Q-switching configuration where a Q-switcher and a frequency-doubling crystal was needed, low loss and high efficiency characteristics were realized by only using KTP crystal in our experimental setup. With the new type of KTP crystal doped particular element, the great green pulsed output was obtained continuously for a long time with no sign of electrochromic damage. In this paper, we demonstrated a relatively new and compact intracavity frequency-doubled and Q-switched Nd:YVO<SUB>4</SUB> laser. The short- cavity laser was longitudinally pumped with a diode laser.
A QCW 100 W LD array side pumped high power laser has been developed. The 1.06 micrometer laser pulse energy of 2 mJ, with the pulse width 20 ns and repetition frequency 70 Hz to approximately 5 KHz is obtained. Using the non-cylinder lens focus system developed by our group, the efficient conversion of pump energy into 1.06 micrometer TEM<SUB>00</SUB> mode is achieved with 17% optical-optical efficiency. The effect of vibrating output coupler in the laser resonator strengths the output power has been found for the first time.
We report here the Nd:YAP-KTP red laser pumped by LD for pumping Cr:LiSAF tunable laser. Using a CW 802 nm LD of 3 W, 670 nm CW red laser of 95 mW has been measured. The red laser is used to pump Cr:LiSAF laser, and over 4 mW CW laser from the Cr:LiSAF laser has been measured. They are to our knowledge the first Nd:YAP-KTP red laser pumped by LD and the first Cr:LiSAF laser pumped by Nd:YAP-KTP red laser.
We report here LD pumped Q-Switched LNYAB Self-frequency-doubling Laser. Under 570mW of O.8O2.tm pumping power, the series pulses of O.53j.im green laser with 4.2ns of pulse width and 750W of peak power have been measured . The laser reliably operates when Q—switching rate ranges from CW to 100kHz. The highest peak power was obtained at repetition rate of 10kHz. To our knowledge, it is the first LD pumped acoustooptic Q-switched LNYAB green laser in the world and should be a desirable and reliable pulsed green laser source in the future.
KEY WORDS: Self-frequency-doubling Laser, LD Pumped, LNYAB, Q-Switched
Here we report the LD pumped miniature 1.06 micrometers Nd:YAG solid lasers. Pumped by the LD of 1 W power, 420 mw of 1.06 micrometers CW laser has been obtained. The output stability is better than +/- 3%, and the divergence angle is smaller than 4 mrad. The volume of the device is very small and it is suitable to be applied in the optical fiber communication systems and optical fiber sensing system.
Here we report LD pumped solidified miniature Nd:YAG laser and Nd:YVO<SUB>4</SUB> laser with KTP crystal as intracavity frequency doubling material. Using 1W LD 70 mW and 80 mW of the green laser output in TEM<SUB>oo</SUB> mode have been measured for Nd:YAG laser and Nd:YVO<SUB>4</SUB> laser, respectively. The output stability is better than +/- 3 percent and the beam quality coefficient M<SUP>2</SUP> is smaller than 1.2. The laser is small is size and very suitable for optical recording and storage.
We have developed three types of green solid state lasers pumped by laser diodes. A green laser outputs up to 24.5 mW at 532 nm with Nd:YAG/KTP crystal, the second outputs up to 19 mW with Nd:YVO<SUB>4</SUB>/KTP crystal and the third up to 29 mW with LNYAB crystal. The experiments setups and results are discussed. Comparison of these three kinds of lasers are presented.
An LD pumped YAG-KTP intracavity frequency doubling laser has been developed. A cw linearly polarized green laser at 532 nm is obtained. The pumping threshold, output power, and slope efficiency are 12 mW, 2.5 mW, and 5%, respectively. The influence of the states of pump light on transverse modes of the frequency doubling laser has been studied. The experimental methods and results are reported briefly.
The first modified neodymium yttrium aluminum borate (M-NYAB) self-doubling laser pumped by LD has been designed. The properties of the lasers are much better than those of NYAB self-doubling lasers pumped by LD. All of the M-NYAB self-doubling lasers pumped by LD can operate in TEM<SUB>00</SUB> mode and the pumping threshold is less than one-third of that of LD pumped SFD laser with NYAB. The pumping threshold, maximum output power, and slope efficiency are 3.6 mW, 29 mW, and 4.8%, respectively.
We report on the first laser diode pumped Nd:YVO<SUB>4</SUB> fundamental and second harmonic lasers made in China. The threshold pumping power of the LD-pumped Nd:YVO<SUB>4</SUB> fundamental laser is 4.5 mW. The cw 1064 nm output power is 64 mW with slope efficiency of 10.7%. The threshold pumping power of the LD-pumped Nd:YVO<SUB>4</SUB> intracavity frequency doubling laser with KTP doubler is 12.5 mW. Nineteen mW of fundamental-mode 532 nm green laser were measured with a slope with a slope efficiency of 3.2$%. Experiment setups and results are discussed.