• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.88-89
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• 1999

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.669-673
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• 2003

We fabricated a buried-ridge waveguide laser diode (B-RWG LD) which has more advantages for obtaining lateral single mode operation on the same ridge width and for the planarization of the device surface, compared to the conventional RWG LD. In this LD, the difference of the lateral effective refractive index can be controlled by the thickness of the InGaAsP layer which is grown on the active and the p-InP layers. The InGaAsP multiple quantum well was grown on a n-InP substrate by the CBE. The buried ridge structure was formed by selective wet etchings, followed by liquid phase epitaxy methods. The fabricated LD with the ridge width of 7 ${\mu}{\textrm}{m}$ showed a linear increase of the optical power up to 20 ㎽ without any kinks and a saturated output power of more than 80 ㎽. By measuring the far field pattern, we demonstrate that LDs with the ridge widths of 5 ${\mu}{\textrm}{m}$ and 7 ${\mu}{\textrm}{m}$ were operated in a lateral single mode up to 2.7I$_{th}$ and 2.4I$_{th}$, respectively.ely.

• ETRI Journal
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• v.30 no.3
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• pp.480-482
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• 2008

A novel InGaAsP/InP buried-ridge waveguide laser diode structure is proposed and demonstrated for use as a single-mode laser. The lateral mode of the proposed device can be controlled by adjusting the composition and thickness of the InGaAsP layer grown over the active region. Stable single-mode operation without kinks or beam-steering is achieved successfully with lateral and transverse in the junction plane even for the device with the ridge width of 9 ${\mu}m$ up to an injection current of 500 mA.

• Korean Journal of Optics and Photonics
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• v.12 no.4
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• pp.312-319
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• 2001

We proposed a B-RWG LD (Buried-ridge waveguide laser diode) having more merits than a conventional RWG-LD. It's ridge width is controlled easily, it has the advantage of being more planar than the RWG-LD and it is possible to control refractive index with growth layer thickness. Before fabricating the device, we designed the optimal device for single mode, high efficiency and high power operation. From theoretical analysis, we have to control the $d_2, d_3$ layer thicknesses for lateral effective index difference, $\Delta_{nL}$ to be higher than critical value, and simultaneously consider the ridge width for single mode and low threshold current operation. As a result, it is possible to make a single mode LD having the ridge width of $6~9{\mu}m$ if the lateral effective index difference was controlled properly. perly.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.9
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• pp.634-642
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• 2001

We calculate the facet reflectivity of buried channel waveguides and ridge waveguides as a function of the waveguide width for various thicknesses using the angular spectrum method and the two dimensional field profiles obtained by the variational method (VM) and the effective index method (EIM). The variation of the reflectivity of buried channel waveguides as a function of the waveguide width is large, while that of ridge waveguides is very small. The accuracy of the field profiles necessary for the calculation of the facet reflectivity using the angular spectrum method greatly affects that of the facet reflectivity. The difference between the exact reflectivity and that using EIM increases as the waveguide width and thickness decreases due to the inaccuracy of the field profiles obtained by EIM. However, the difference between the exact reflectivity and that using VM is smaller than that using EIM regardless of waveguide width and thickness. The difference between the facet reflectivities u sing EIM and VM is small in the area where the EIM works very well.

• Korean Journal of Optics and Photonics
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• v.9 no.5
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• pp.307-314
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• 1998

We have studied the effects of interface on polarization dependence of waveguide and designed the polarization independent 2-dimensional waveguides on InP for arrayed waveguide grating. To figure out the effects of interface on polarization dependence, we have solved the 1-dimensional wave equation using a transfer matrix method. It is shown that the birefringence becomes stronger as the number of interfaces increases. In order to design polarization independent 2-dimensional waveguides, we have used effective index method. The structures considered are ridge type, raised strip type, and buried type waveguide. In the cases of ridge and raised strip type, conventional effective index method was used. In the case of buried type corrected effective index method was used. We have determined the height and width of waveguides such that the waveguides become polarization independent.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.469-474
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• 2004

We have fabricated and designed wavelength-tunable sampled grating distributed Bragg reflector laser diodes(SGDBR-LD) by using, for the first time, planar buried heterostructures(PBH). The diodes have low threshold current values and high-performance of laser operation. Growth condition using metal organic chemical vapor deposition(MOCVD) was optimized for the formation of a good butt-coupling at the interface. A maximum output power of the fabricated device was 20 mW under 200 mA continuous wave(CW) operation at $25^{\circ}C$. Average threshold current and voltage were 12 mA and 0.8 V, approximately. This output power is higher than those of ridge waveguide(RWG) and buried ridge stripe(BRS) structures by amounts of 9 mW and 13 mW, respectively. We obtained a tuning range of 44.4nm which is well matched with the target value of our design. The side mode suppression ratio of more than 35 dB was obtained for the whole tuning range. Optical output power variation was less than 5 dB, which is 4 dB smaller than that of RWG structures.

• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.509-514
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• 2003

Mach-Zehnder interferometric wavelength converters with monolithically integrated semiconductor optical amplifiers (SOA's) have been fabricated and characteristics of wavelength conversion at 10 Gb/s have been investigated for wavelength span of 40 nm. The devices have been achieved by using a butt-joint combination of buried ridge structure type SOA's and passive waveguides. In the integration, a new method has been applied that removes p+InP cladding layer leading to high propagation loss and forms simultaneously the current blocking and the cladding layer using undoped InP. The module packaging has been achieved by using a titled fiber array for effective coupling into the tilted waveguide in the wavelength converter. Using the module, wavelength conversion with power penalty lower than 1 ㏈ at 10 Gb/s has been demonstrated for wavelength span of 40 nm. In addition, it is show that the module can provide 2R (re-amplification, re-shaping) operation by demonstrating the conversion with the negative penalty.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.454-459
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• 2003

We report the first demonstration of 10 Gb/s wavelength conversion in a Mach-Zehnder interferometric wavelength converter monolithically integrated with a loss-coupled DFB probe source. The integrated device is fabricated using a BRS (buried ridge stripe) structure with an undoped InP clad layer on the top of a passive waveguide to reduce high propagation loss. The device exhibited a static extinction ratio of 11 dB. Good performance at 10 Gb/s is obtained with an extinction ratio of 7 dB and a power penalty of 2.8 dB at a 10$^{-9}$ bit error rate.