• Korean Journal of Optics and Photonics
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• v.16 no.5
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• pp.406-410
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• 2005

we propose an external cavity laser which can adjust the number of longitudinal laser mode by using a tunable chirped fiber. Bragg grating. By inducing a tunable temperature gradient in a uniform fiber Bragg grating, the bandwidth of the unform fiber Bragg grating can be tuned. With the chirped fiber Bragg grating as an external reflector of the external cavity laser, the number of longitudinal laser mode was able to be tuned from one to two or three modes.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.327-330
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• 2003

We present the fabrication and measured performance of a wavelength tunable Butt coupled DBR-LD. An average coupling efficiency between active layer and passive waveguide layer was measured over 85％per facet, and the average threshold current was 21 ㎃ for the waveguide integrated DBR laser. High output power of Butt coupled DBR-LD was obtained over 25 ㎽. As high as 25 ㎽ of output power was achieved by the butt coupled method. The maximum wavelength tuning range is about 7.4 nm, and the side mode suppression ratio was more than 40 ㏈ using 1.3 ${\mu}{\textrm}{m}$ InGaAsP waveguide layer.

• Current Optics and Photonics
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• v.5 no.4
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• pp.384-390
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• 2021

This paper presents a wide-range tunable wavelength-locking technology based on optoelectronic oscillation (OEO) loops for optical fiber sensors and microwave photonics applications, explains the theoretical fundamentals of the design, and demonstrates a method for locking the relative wavelength differences between a leader semiconductor laser and its follower lasers. The input of the OEO loop in the proposed scheme (the relative wavelength difference) determines the radio-frequency (RF) signal frequency of the oscillation output, which is quantized into an injection current signal for feedback to control the wavelength drift of follower lasers so that they follow the wavelength change of the leader laser. The results from a 10-hour continuous experiment in a field environment show that the wavelength-locking accuracy reached ±0.38 GHz with an Allan deviation of 6.1 pm over 2 hours, and the wavelength jitter between the leader and follower lasers was suppressed within 0.01 nm, even though the test equipment was not isolated from vibrations and the temperature was not controlled. Moreover, the tunable range of wavelength locking was maintained from 10 to 17 nm for nonideal electrical devices with limited bandwidth.

• Current Optics and Photonics
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• v.3 no.1
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• pp.27-32
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• 2019

We present an autofocus tracking system implemented by the digital refocusing of digital holographic microscopy (DHM) and the tunability of an electrically tunable lens (ETL). Once the defocusing distance of an image is calculated with the DHM, then the focal plane of the imaging system is optically tuned so that it always gives a well-focused image regardless of the object location. The accuracy of the focus is evaluated by calculating the contrast of refocused images. The DHM is performed in an off-axis holographic configuration, and the ETL performs the focal plane tuning. With this proposed system, we can easily track down the object drifting along the depth direction without using any physical scanning. In addition, the proposed system can simultaneously obtain the digital hologram and the optical image by using the RGB channels of a color camera. In our experiment, the digital hologram is obtained by using the red channel and the optical image is obtained by the blue channel of the same camera at the same time. This technique is expected to find a good application in the long-term imaging of various floating cells.

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.5
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• pp.547-553
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• 2024

Precise control over the morphology of nanostructures is critical for tailoring their physical and chemical properties. This study addresses the challenge of developing a simple, integrated method for synthesizing both 1D and 2D colloidal Cu nanostructures in a single system, achieving successful tuning of their localized surface plasmon resonance (LSPR) properties. A facile hydrothermal synthesis utilizing potassium iodide (KI) and hexadecylamine (HDA) is presented for controlling Cu nanostructure morphologies. The key to achieving 1D nanowires (NWs) and 2D nanoplates (NPs) depends on the controlled adsorption of HDA molecules and iodide (I-) ions on specific crystal facets. Depending on the morphologies, the resultant Cu nanostructures exhibit tunable LSPR peaks from 558 nm [nanoplates (NPs)] to 590 nm [nanowires (NWs)]. These results pave the way for the scalable and cost-effective production of plasmonic Cu nanostructures with tunable optical properties, holding promise for applications in sensing, catalysis, and photonic devices.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.12a
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• pp.2-2
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• 2004

• Proceedings of the Korean Vacuum Society Conference
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• 2007.02a
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• pp.37-37
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 1998.08a
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• pp.168-169
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• 1998

• Proceedings of the Optical Society of Korea Conference
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• 1998.08a
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• pp.166-167
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• 1998