• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.69-70
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• 2006

• Current Optics and Photonics
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• v.5 no.1
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• pp.59-65
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• 2021

This paper reports a tunable diode-pumped folded intracavity Q-switched singly resonant optical parametric oscillator based on multi-period MgO:PPLN. A wide tuning mid-infrared parametric light from 2.78 ㎛ to 4.17 ㎛ was obtained in real time by changing the poled periods and temperatures. The maximum output power of 1.89 W at 3.2 ㎛, 1.53 W at 3.5 ㎛, 0.87 W at 3.8 ㎛ and 0.486 W at 4.1 ㎛ were achieved. The highest optical-optical conversion efficiency was 7.89%. During experiments, a range tunable output of 2.78-4.17 ㎛ in the mid-infrared range was achieved.

• Current Optics and Photonics
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• v.3 no.6
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• pp.577-582
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• 2019

We report on a continuous-wave (cw) optical parametric oscillator (OPO) optimized for mid-infrared emission above 5.0 ㎛. The OPO is based on a magnesium-oxide-doped periodically poled LiNbO₃(MgO:PPLN) crystal with a fan-out grating design. A linear two-mirror cavity resonating both at the pump and signal wavelengths is stabilized to the pump laser by using the modified Pound-Drever-Hall (PDH) method. The idler wavelength is continuously tunable from 4.7 ㎛ up to 5.3 ㎛ by varying the poling period of the fan-out grating crystal. Pumped by a diode-pumped solid state (DPSS) laser with a power of 1.1 W at 1064 nm, the maximum idler output power is measured to be 5.3 mW at 4.8 ㎛. The output power above 5.0 ㎛ is reduced to the hundreds of ㎼ level due to increased absorption in the crystal, but is stable and strong enough to be measured with a conventional detector.

• Current Optics and Photonics
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• v.5 no.2
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• pp.186-190
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• 2021

In this study, a compact, picosecond, mid-infrared 3.8 ㎛ MgO:PPLN optical parametric oscillator (OPO) laser output with high peak power is realized using a master oscillator power amplifier (MOPA) 1 ㎛ solid-state laser seeded by a picosecond fiber laser as the pump source. The pump source was a 50 MHz and 10 ps fiber seed source. After AOM pulse selection and two-stage solid-state amplification, a 1,064 nm laser output with a repetition frequency of 1-2 MHz, pulse width of 9.5 ps, and a maximum average power of 20 W was achieved. Furthermore, a compact short cavity with a unsynchronized pump is adopted through the design of an OPO cavity structure. When the injection pump power was 15 W and the repetition frequency was 1 MHz, the average output power of idler light was 1.19 W, and the corresponding peak power was 119 kW. The optical conversion efficiency was 7.93%. When the repetition frequency was increased to 2 MHz, the average output power of idler light was 1.63 W, the corresponding peak power was 81.5 kW, and the optical conversion efficiency was 10.87%. At the same time, the output wavelength was measured at 3,806 nm, and the beam quality was MX2 = 3.21 and MY2 = 3.34.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.341-342
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• 2009

• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.229-236
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• 2008

The optimum conditions of second harmonic generation (SHG) can be successfully achieved experimentally using single pass and double pass methods of a pumping beam. The beam has a power of several Watts radiated by a DOFA (Diode Laser Oscillator & Fiber Amplifier) system, which is a high power CW wavelength tunable infrared laser system, in a PPLN (Periodically Poled MgO doped Lithium Niobate) nonlinear crystal. In the case of a single pass method, the parameters are the wavelength of 535 nm for SHG and the output power of 245 mW generated from the pumping input beam with wavelength of 1070 nm and the power of 2.45 W at phase matching temperature of $108.9^{\circ}C$. The conversion efficiency of SHG was 10%. In order to enhance the output of SHG, the double pass method of the SHG system of a PPLN using a concave mirror for the retroreflection and a pair of wedged flat windows for phase compensation was also presented. In this double pass system, we obtained the SHG output beam with the wavelength of 535 nm and the maximum power of 383 mW at optimum phase matching temperature of $108.5^{\circ}C$ by using an incident pumping beam with wavelength of 1070 nm and the power of 2.45 W. The maximum conversion efficiency is 15.6%, which is more than that of the single pass method.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.64-65
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• 2009

• Current Optics and Photonics
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• v.3 no.1
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• pp.33-39
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• 2019

We report development of a frequency-stabilized mid-infrared continuous-wave (cw) optical parametric oscillator (OPO) based on a fan-out grating MgO:PPLN crystal pumped at 1064 nm. The OPO resonator was designed as a pump-enhanced standing-wave cavity that resonates to the pump and signal beams. To realize stable operation of the OPO, we applied a modified Pound-Drever-Hall technique, which is a well-known method for powerful laser frequency stabilization. Tuning a poling period of the fan-out grating of the crystal allows wavelength-tunable OPO outputs from 1510 nm to 1852 nm and from 2500 nm to 3600 nm for signal and idler beams, respectively. At the idler wavelengths of 2500 nm, 3000 nm and 3500 nm, we achieved more than 50 mW of output powers at a pumping power of 1.1 W. The long-term stability of the OPO was confirmed by recording the power and wavelength variations of the idler for an hour.

• Korean Journal of Optics and Photonics
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• v.30 no.4
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• pp.154-158
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• 2019

We have used a mid-IR (mid-infrared) continuous-wave (cw) optical parametric oscillator (OPO), developed previously and described in Ref. 12, to build a performance-evaluation setup for a mid-IR spectrometer. The used CW OPO had a wavelength tuning range of $ 2.5-3.6{\mu}m$ using a pump laser with a wavelength of 1064 nm and a fan-out MgO-doped periodically poled lithium niobate (MgO:PPLN) nonlinear crystal in a concentric cavity design. The OPO was combined with a near-IR integrating sphere and a Fourier-transform IR optical spectrum analyzer to build a performance-evaluation setup for mid-IR spectrometers. We applied this performance-evaluation setup to evaluating a mid-IR spectrometer developed domestically, and demonstrated the capability of evaluating the performance, such as spectral resolution, signal-to-noise ratio, spectral stray light, and so on, based on this setup.