• Korean Journal of Optics and Photonics
• /
• v.25 no.1
• /
• pp.38-43
• /
• 2014

An external cavity laser supporting two wavelengths is demonstrated by incorporating polymer waveguide Bragg reflectors and a superluminescent light-emitting diode. An oversized rib waveguide structure and Bragg gratings are designed by using the effective-index and transmission-matrix methods. Bragg gratings with different periods are inscribed on a polymer waveguide through double-exposure laser interferometry. In order to tune the cavity loss affected by the reflectivity of Bragg gratings, a Bragg reflectors with varying length is incorporated. Two-wavelength-mode lasing is achieved for the device consisting of 2-mm long, 537-nm period gratings and 2.2-mm long, 540-nm period gratings; the lasing wavelengths are 1554 nm and 1564 nm, with an output power close to 0 dBm, a 20-dB bandwidth of 0.2 nm, and a side-mode suppression ratio of 45 dB.

• Proceedings of the Optical Society of Korea Conference
• /
• 2001.02a
• /
• pp.166-167
• /
• 2001

과장 변환기는 WDM (wavelength division multiplexing) 시스템에서 wavelength relocation을 가능하게 하여 시스템의 유연성과 효율성을 향상시킨다는 측면에서 매우 중요한 기능을 갖는다. WDM 시스템의 채널의 수가 점차 증가함에 따라 채널의 간격이 100 GHz에 이르고 있으며 향후 더욱 조밀해 질것이다. 이러한 DWDM (Dense WDM)시스템에서 사용될 수 있는 파장변환기는 100 GHz단위의 파장변환 기능과 광대역 가변 변위가 필수적이다. (중략)

• Proceedings of the Optical Society of Korea Conference
• /
• 2006.02a
• /
• pp.315-316
• /
• 2006

• Proceedings of the Optical Society of Korea Conference
• /
• 2006.07a
• /
• pp.71-72
• /
• 2006

• Proceedings of the Optical Society of Korea Conference
• /
• 2006.07a
• /
• pp.313-314
• /
• 2006

• Korean Journal of Optics and Photonics
• /
• v.23 no.5
• /
• pp.227-232
• /
• 2012

A large-signal time-domain model is implemented to analyze an FG-LD (Fiber Grating Laser Diode) in which a reflective laser diode is hybrid-integrated with a fiber Bragg grating (FBG). When the length of the externally integrated resonator is 8 mm, in which the effective FBG length of 2.1 mm is included, a static frequency chirp of 0.44 GHz and a dynamic frequency chirp of 6.4 GHz are observed. In addition, it is also observed that the eye of the 10Gbps NRZ signal is well open. The FG-LD is expected to be a cost-effective solution for a 10Gbps-class single wavelength laser covering a span of 50 km range.

• Korean Journal of Optics and Photonics
• /
• v.10 no.6
• /
• pp.524-526
• /
• 1999

It is observed that the mode spacing of an cxternal cavity semiconducror laser can be altered dramatically by the insertion of an intracavity etalon. 111e mode spacing is decreased as a function of etalon's reflectivity and this effect is quantitatively explained by an analysis of resonant modes. We abo show that this effect provides a precise and convenient alternative for determining the coating reflectivity of a high reflectivity etalon. talon.

• International Journal of Precision Engineering and Manufacturing
• /
• v.8 no.4
• /
• pp.22-26
• /
• 2007

We describe a new way of implementing absolute displacement measurements by exploiting the optical comb of a femtosecond pulse laser as a wavelength ruler, The optical comb is stabilized by locking both the repetition rate and the carrier offset frequency to an Rb clock of frequency standard. Multiwavelength interferometry is then performed using the quasi-monochromatic beams of well-defined generated wavelengths by tuning an external cavity laser diode consecutively to preselected light modes of the optical comb. This scheme of wavelength synthesizing allows the measurement of absolute distances with a high precision that is traceable to the definition of time. The achievable wavelength uncertainty is $1.9{\times}10^{-10}$, which allows the absolute heights of gauge blocks to be determined with an overall calibration uncertainty of 15 nm (k = 1). These results demonstrate a successful industrial application of an optical frequency synthesis employing a femtosecond laser, a technique that offers many possibilities for performing precision length metrology that is traceable to the well-defined international definition of time.

• Korean Journal of Optics and Photonics
• /
• v.19 no.4
• /
• pp.334-340
• /
• 2008

We investigated the electromagnetically induced transparency (EIT) and the Hanle spectrum in a paraffin coated Rb vapor cell. The EIT spectrum was observed in the $F_g=2$, $3{\rightarrow}F_e=3$ transition of the $^{85}Rb$ $D_1$-line by using two independent external cavity diode lasers, and the Hanle spectrum was observed by using one external cavity diode laser in the $\Lambda$-type scheme between the Zeeman sublevels of the $F_g=2{\rightarrow}F_e=1$ transition of the $^{87}Rb$ $D_1$-line. In the Hanle spectrum, we could observe the dual-structured spectrum in the paraffin coated vapor cell. We investigated the dual-structured lineshape by applying an external magnetic field, and varying the direction of the magnetic field. The narrow linewidth of dual-structured EIT was measured to be approximately 200 Hz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.477-478
• /
• 2006

Characteristics of InAs/GaAs quantum dot (QD) ridge laser diodes (LDs) are investigated for high-power $1.3\;{\mu}m$ applications. For QD ridge LDs with a $5-{\mu}m$-wide stripe and a 1-mm-long cavity, the emission wavelength of 1284.1 nm, the single-uncoated-facet CW output power as high as 90 mW, the external efficiency of 0.31 W/A and the threshold current density of $800\;mA/cm^2$ are obtained. The linewidth enhancement factor ($\alpha$-factor) is successfully measured to be between 0.4 and 0.6, which are about four times as small values with respect to conventional quantum well structure. It is possible that this result significantly reduce the filamentation of far-field profiles resulting in better beam quality for high power operation.