• Korean Journal of Optics and Photonics
• /
• v.21 no.6
• /
• pp.254-258
• /
• 2010

We investigate an optical technique for beam shaping and optical amplification of a pulsed laser diode without variation of its original properties, such as repetition rate and pulse duration. The horizontal and longitudinal sizes of the pulsed laser diode are 300 and $2{\mu}m$, respectively, and its output power is $1.1mW/cm^2$. The multimodal and elliptical pulse shape of the laser diode is converted to the single-modal and Gaussian pulse shape by using a lensed optical fiber. Since the single-modal lensed fiber coupling from the multimodal pulsed laser diode degrades the output power severely, the output power of the pulsed laser diode is dramatically enhanced by using an optical amplification method based on master oscillated power amplification (MOPA). The pulse qualities of the laser diode are not changed after amplifying the pulse power and the output power was finally measured to be $29mW/cm^2$.

• Current Optics and Photonics
• /
• v.4 no.2
• /
• pp.127-133
• /
• 2020

We successfully constructed a passively Q-switched Yb:YAG laser ignitor pumped by a diode laser with low power and long pulse width. To the best of our knowledge, this is the first study to achieve a quasi-MW output power from an optimized Q-switch Yb:YAG laser ignitor by using a pumping diode laser module emitting at under a power of 23 W. The output pulse energy of our optimized laser is 0.98 mJ enclosed in a 1.06 ns pulse width, corresponding to a peak power of 0.92 MW.

• Proceedings of the KIEE Conference
• /
• 1987.07a
• /
• pp.54-57
• /
• 1987

A new method optical short pulse generation using diode lasers under the negative electro-optic feedback are proposed. The self-pulsing is induced by feedback itself and the pulse is formed by the interaction of feeback signal and the dynamics of the diode laser. The simulated pulse width is on the order of picosecond with several GIIz repetition rates.

• Proceedings of the IEEK Conference
• /
• 2000.06e
• /
• pp.106-109
• /
• 2000

The diode characteristics for therapy radiation sensor have been studied by irradiating therapy radiation from the MM22 microtron accelerator. Signal processing has been performed in the pulse mode which can process the signal fast. We have designed integrator, peak detector and synchronization circuit to detect diode signal in the pulse mode for implementation of portal image. We also read the diode signal by A/D board and displayed the peak value with LabView program. Because the quality of portal image obtained by film in the case of therapy radiation is much worse than that of diagnostic film, Digital radiography system by rectifier diode detector was suggested for portal Image.

• Korean Journal of Optics and Photonics
• /
• v.19 no.4
• /
• pp.320-326
• /
• 2008

The output characteristics of a laser-diode pumped electrooptic Q-switched Nd:YAG ceramic laser were investigated. The output energy of a Q-switched Nd:YAG ceramic laser was optimized under an output coupler reflectivity of 77%, a laser-diode pulse width of $1,000\;{\mu}s$, and a delay time of $985\;{\mu}s$. The output energy of the Q-switched pulse was measured to be 0.35 mJ with a pulse width of 4 ns under a pump energy of 17.9 mJ. The output efficiency and the peak power were 1.9% and 87.5 kW, respectively.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.7
• /
• pp.916-922
• /
• 2014

Diode rectifiers have been widely used for an AC to DC converter. But a big problem is that they include large harmonics components in the input currents. A 12-pulse configuration with phase shifting transformer is useful for reducing them. however, it still includes the ($12{\pm}1$)th (m; integer) harmonics in the input currents. In this paper, we propose a single-phase square wave auxiliary voltage supply which is inserted in the middle DC bus. It reduces harmonics especially the 11th and 13th and the harmonic characteristic becomes almost equivalent to a 24-pulse rectifier. Theoretical analysis of the combined 12-pulse diode rectifier with the auxiliary supply is presented and a control method of the auxiliary supply is proposed. The reduction in the input current harmonics is verified by simulation using software PSIM.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.4 no.5
• /
• pp.423-432
• /
• 1999

This paper proposes a 12­pulse diode rectifier system with low kVA components suitable for powering switch mode power supplies or ac/dc converter applications. The proposed 12-pulse system employs a polyphase transformer, a zero sequence blocking transformer (ZSBT) in the dc link, and an interphase transformer. Results produce near equal leakage inductance in series with each diode rectifier bridge ensuring equal current sharing and performance improvements, The utility input currents and the voltage across the ZSBT are analyzed the kVA rating of each component in the proposed system is computed. The 5th , 7th , 17th and 19th harmonics are eliminated in the input line currents resulting in clean input power. The dc link voltage magnitude generated by the proposed rectifier system is nearly identical to a conventional to a conventional 6-pulse system. The proposed system is suitable to retrofit applications as well as in new PWM drive systems. Simulation and experimental results from a 208V , 10kVA system are shown.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.4 no.3
• /
• pp.304-309
• /
• 1999

In this paper, a new 24longleftarrowpulse diode rectifier system based upon the conventional series-connected 12-pulse rectifier is p proposed with the least number of switching devices and low VA rating of the additional passive components. The p proposed approach does not employ any active switching devices. Therefore, the system is rugged and simple to i implement. Detailed analysis with VA rating calculation of the components is presented and experimental results from a a 220V, 3kV A rectifier system verify the proposed concept.

• 전기의세계
• /
• v.11
• /
• pp.14-17
• /
• 1963

정확하게 control된 pulse의 용도는 과학과 공업이 발달될수록 날로 많아져 가고 있는데 그의 일부는 대전력을 취급하는 경우로서, Radar에 대한 응용을 들 수 있다. 한편, 요지음 gallium-arsenide등 반도체 diode를 사용해서 Laser action을 일으킬 수 있다는것이 발견되어 G.E. 및 IBM등에서 개발되고 있다. 이 경우에, continuous emission도 가능하지만 흔히, intermittent operation을 시켜야 할 때가 많기 때문에 timed pulse source가 필요하게 된다. 또 한편, spot welding의 경우에도 이러한 pulse source가 필요하게 된다. 이들을 크게 나누어 source를 AC로 할 경우와 DC로 할 경우가 있는데, 전자의 경우는 thyratron을 사용할 경우가 많게 될 것이다. DC의 경우나 AC의 경우에나 잘 shape되고 time된 pulse source를 만들어 놓으면 진공관이나 thyratron이나 같은 모양으로 drive할 수 (thyratron의 경우는 trigger)있을 것이기 때문에, 이러한 pulse source를 만들 필요가 있게 된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.05a
• /
• pp.869-871
• /
• 2012

In this paper, we make silicon photodiodes for the detection of pulsed radiation that affects electronics devices and study the output characteristics of photodiodes using circuit design. We conducted the simulation for pulse sensing circuit and experimented the photodiode output characteristics using a high luminance light emitting diode. The results can be used for the design of the input sensor that is trigger of additional module for protecting a electoronics circuit from high energy pulse radiation.