• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.153-158
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• 2009

Stable and tunable dual-wavelength erbium-doped fiber ring laser(EDFL) using a single fiber Bragg grating(FBG) and two coil heaters is proposed and demonstrated. Installing two identical coils into a single FBG, the FBG is symmetrically divided into two different portions. While a current supply to the coil, the refractive index of the FBG under the coil is changed. The FBG can operate as a joint of two different FBGs. Due to the thermo-optic effect of a fiber, the resonance wavelength split into two peaks. The spacing between two adjacent channels was changed as much as the difference of heating power. It was tuned up to 3 nm of wavelength under the electrical power with a 1000 mW. Moreover, the lasing wavelength can be individually tuned without influencing to the adjacent channel.

• Current Optics and Photonics
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• v.2 no.6
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• pp.582-588
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• 2018

A $Nd:YVO_4$ laser dual-end-pumped by a wavelength-locked 878.6 nm laser diode is presented. At the repetition rate of 500 KHz, the absorbed pump power of 58 W, an output power of 26.1 W at 1064 nm is obtained, corresponding to an optical-optical efficiency of 45%. The pulse width is 44.2 ns. Meanwhile, the effects of traditional 808 nm pumping and 878.6 nm dual-end-pumping on the output laser beam quality and pulse width are compared and analyzed in an experiment.

• Korean Journal of Optics and Photonics
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• v.21 no.5
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• pp.181-184
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• 2010

A simple technique for a flexibly tunable and switchable dual wavelength-switchable erbium-doped fiber (EDF) laser using fiber Bragg gratings is proposed and demonstrated by using both linear cavity loss controlling and homogeneous gain broadening of the EDF. The oscillating wavelength switching is successfully realized by using the modulation of the acousto-optic modulator driven by the RF signal. The wavelength spacing and lasing wavelength of the proposed wavelength-switchable laser can also be controlled by using the bending-induced tension or compression strain. The proposed tunable dual wavelength-switchable fiber laser has a lot of advantages, such as a high extinction ratio larger than 40dB and a high tunability of ~7.2 nm/$m^{-1}$.

• ETRI Journal
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• v.33 no.5
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• pp.810-813
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• 2011

We report the use of a widely tunable detuned dual-mode laser diode (DML) as a compact and portable continuous-wave THz emitter. The wavelength difference between the two lasing modes of this DML can be tuned from 2.4 nm to 9.3 nm by using integrated microheaters. The power difference between these modes is less than 1 dB, and the side-mode suppression ratio is greater than 30 dB over the entire tuning range.

• Medical Lasers
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• v.9 no.2
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• pp.110-118
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• 2020

The non-ablative fractional dual laser is equipped with two types of lasers, 1550 nm and 1927 nm in one device, and was approved by the United States Food and Drug Administration in 2013. The advantages of the non-ablative fractional laser (NAFL) include fewer side effects such as erythema, edema, post-laser pigmentation, and scab formation. Thus, the NAFL is preferred by both practitioners and consumers because it is convenient and safe for use. The 1550 nm erbium glass and 1927 nm thulium lasers are representative NAFLs that have been developed separately and are often used as a single-wavelength laser with proven clinical efficacy in various indications. The 1550 nm wavelength laser penetrates the dermis layer and the 1927 nm wavelength laser is effective for epidermal lesions. Therefore, targeting the skin layer can be easily achieved with both the 1550 and 1927 nm lasers, respectively, or in combination. Clinically, the 1550 nm laser is effective in the treatment of mild to moderate sagging and wrinkles, scars, and resurfacing. The 1927 nm laser improves skin texture and treats skin pigmentation and wounds. It can also be used for drug delivery. The selection and utilization rate of NAFL has been increasing in recent times, due to changes in lifestyle patterns and the need for beauty treatments with fewer side effects and short downtime. In this study, we present a plan for safe and effective laser therapy through a review of literature. Clinical applications of the multifunctional NAFL are also described.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.716-721
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• 2016

A single-and dual-wavelength switchable polarized Yb-doped double-clad fiber laser around 1120 nm based on a pair of fiber Bragg gratings (FBGs) is demonstrated. The polarization-maintaining (PM) linear cavity is composed of a double clad PM Yb-doped fiber (YDF) and a pair of PM FBGs. The laser can operate in stable dual-wavelength or wavelength-switching modes due to the polarization hole burning (PHB) and the spatial hole burning (SHB) enhanced by the PM linear cavity. In dual-wavelength operation, the two orthogonally polarized wavelengths are centered at 1118.912 nm and 1119.152 nm, with an interval of 0.24 nm and a signal to noise ratio (SNR) of 35 dB. The maximum output power is 14.67 W when the launched LD pump is 24 W corresponding to an optical efficiency of 61.1%. The lasing lines switchover may be realized by adjusting the polarization controller (PC) fitted in the cavity. The two single-wavelengths are 1118.912 nm and 1119.152 nm. When the injected LD pump is 24 W, the highest output powers are 7.68 W and 8.64 W corresponding to optical efficiencies of 32% and 36% respectively. The spectral linewidth of the lasing lines are 0.075 nm and 0.07 nm, and the average numerical values of PER aredB and 19.9 dB, respectively.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.239-244
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• 2008

We have realized the swept source optical coherence tomography(SS-OCT) by using the self-fabricated wavelength swept laser(wavelength tuning range : 80nm, line-width : 0.12nm, wavelength sweeping rate : 50Hz). In addition, we have used the dual balanced detector that could make a mirror image in OCT display suppressed. We can also fabricate the comb filter of Michelson interferometer type for fast-signal processing in OCT. Using this SS-OCT system for measuring an mirror, a 1mm-depth glass and an onion, we confirmed that the in vivo epidermal cross-sectional images for them can be obtained appropriately.

• Journal of Biomedical Engineering Research
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• v.17 no.4
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• pp.491-498
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• 1996

The development of a compact two-wavelength Nd:YAG laser for dental and ENT applications is presented. The Nd:YAG resonator generates either 1.06$\mu$m or 1.32$\mu$m. The wavelength selection is made at the control panel. The Nd:YAG laser parameters at 1.06$\mu$m are ; the maximum pulse duration of 150$\mu$s, repetition rates of I-100Hz, and the maximum average power of 25W. At 1.32$\mu$m, the pulse duration is the same where the repetition rates and the maximum average power are I-30Hz and lOW respectively. High voltage power supply consists of a simmer module and two identical high voltage DC converters. In order to make a complete medical laser system, an optical fiber delivery unit, foot pedal and water spray handpiece are also developed. The wavelength selection is reliable since no movement of optical or mechanical components is required. The high voltage power supply is compact, easy to be maintained and applicable for other laser systems due to its modular design.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1995-1997
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• 2007

In this paper we propose a wavelength-switchable fiber ring laser that employs a polarization-dependent fiber band stop filter. The fiber filter was fabricated by inscribing a long-period fiber grating on a high birefringent fiber. Dual-wavelength switching operation was accomplished by controlling the rotatable linear polarizer which rotated the polarization plane of the light circulating through the fiber laser cavity. The amplitude variation of both laser lines was measured to be less than 0.5 dB and the signal-to-amplified spontaneous emission ratio was more than 55 dB.

• Medical Lasers
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• v.8 no.1
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• pp.24-27
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• 2019

Seborrheic keratoses (SKs) have been treated with non-ablative longpulsed (LP) lasers, including LP 532-nm neodymium (Nd): yttrium aluminum garnet (YAG), LP 695-nm ruby, LP 755-nm alexandrite (Alex), and LP 1,064-nm Nd:YAG lasers, with a pulse durations of 1-300 msec. Dual-wavelength LP 755-nm Alex/1,064-nm Nd:YAG laser systems have been used to remove hair follicles and treat various vascular and pigmented disorders by sequentially delivering two pulses of different wavelengths with interpulse intervals in the millisecond range. This paper reports the case of a female patient with multiple, discrete, light brown SKs on the dorsum of both hands that were treated effectively with one session of dual-wavelength LP 1,064-nm Nd:YAG/755-nm Alex laser treatment. The treatment settings for the LP Nd:YAG laser were comprised of a wavelength of 1,064 nm, fluence of 50 J/cm², pulse duration of 5 msec, and beam size of 3 mm. The settings for the LP Alex laser were comprised of a wavelength of 755 nm, fluence of 50 J/cm², pulse duration of 5 msec, and beam size of 3 mm. A hybrid mode was used to automatically deliver LP Nd:YAG and LP Alex laser pulses in succession at interpulse intervals of 20 msec. Six weeks after treatment, the patient exhibited remarkable improvement of the light brown seborrheic keratoses and was satisfied with the results.