Dae-Sung Song

Continuous room-temperature operation of optically pumped two-dimensional photonic crystal lasers at 1.6 /spl mu/m

In this letter continuous operation is realized from two-dimensional slab photonic crystal lasers at room temperature. The laser structure is prepared by wafer fusion of an InGaAsP MQW active layer with an AlAs layer that is wet oxidized into an Al/sub 2/O/sub 3/ layer subsequently. The incident threshold pump power at 0.98 /spl mu/m is 9.2 mW for a /spl sim/10-/spl mu/m-diameter hexagonal cavity lasing at 1.6 /spl mu/m.

Polarization-controlled, single-transverse-mode, photonic-crystal, vertical-cavity, surface-emitting lasers

We developed a polarization-controlled, single-transverse-mode, photonic-crystal, vertical-cavity, surface-emitting laser (PC-VCSEL) by introducing elliptical air holes in the top mirror. The polarization-controlled PC-VCSELs show polarization extinction ratios of over 29 dB. The origin of the polarization stability is explained by the asymmetric polarization mode profile and the asymmetric current injection profile.

Effect of nonradiative recombination on light emitting properties of two-dimensional photonic crystal slab structures

InGaAsP-based two-dimensional photonic crystal light emitting structures are fabricated by employing wafer fusion and characterized optically. The structure does not contain defect regions and the whole area of the photonic crystal is used for light generation and extraction. The effect of nonradiative recombination is studied as a function of pump power. The relative contribution of surface recombination can be as low as 10% as pump power increases since carrier recombination is dominated by Auger recombination. In spite of the large surface-to-volume ratio of the photonic crystal pattern, over four-fold enhancement of photoluminescence extraction efficiency is observed.

Transverse mode control by etch-depth tuning in 1120-nm GaInAs/GaAs photonic crystal vertical-cavity surface-emitting lasers

Transverse mode control by etching depth tuning is demonstration from long wavelength (1120 nm) photonics-crystal vertical-cavity surface-emitting lasers. The non-degenerate single-transverse mode was obtained in 12 /spl sim/ 18-pair-etched PC-VCSELs over the entire operating current range.

InGaAsP microdisk lasers on Al/sub x/O/sub y/

InGaAsP microdisk lasers are fabricated on Al/sub x/O/sub y/ by wafer fusion. Room-temperature continuous-wave operation with threshold pump power of 1.13 mW has been achieved from a 2.2-/spl mu/m diameter microdisk laser. The lasing wavelength with incident pump power redshifts at a rate of 0.28 nm/mW which shows the improved thermal characteristics due to the high thermal conductivity of Al/sub x/O/sub y/ bottom layer.

High-finesse AlxOy/AlGaAs nonabsorbing optical cavity

We report the measured finesse value of ∼390 in nonabsorbing AlxOy/AlGaAs cavities. The nonabsorbing cavity consisting of a bottom AlxOy/AlGaAs distributed Bragg reflector (DBR), an AlxOy spacer layer, and a top AlxOy/AlGaAs DBR is prepared by a wet-oxidation process. The measured resonance linewidth agrees well with that of calculation, indicating very small overall losses in the cavity. The wet-oxidation process does not seem to degrade the interface of the epitaxial layers significantly. The lower bound of maximum achievable reflectivity from the AlxOy DBR is estimated to be >99.95%, assuming an average interface roughness of about 0.6 nm. The maximum achievable finesse of this type of cavity is expected to be larger than that of the all-epitaxial counterpart assuming the same roughness.

Modal Characteristics of Photonic Crystal Fibers

The modal characteristics of the photonic crystal fibers are analyzed using the reliable and efficient plane wave expansion method. The mode profile, effective index and group velocity dispersion are obtained by solving Maxwells vector wave equations without any approximation. The zero dispersion condition of a photonic crystal fiber is derived over a wide range of wavelengths. Higher-order modes are also easily found as a by-product of the plane wave expansion method. This method can be used to quickly and accurately design various optical properties of photonic crystal fibers.

Effect of nonradiative recombination on the light-emitting property of two-dimensional photonic crystals

Summary form only given. Semiconductor light-emitting-structures based on photonic crystals, have been demonstrated recently. Lasing actions and enhanced light extraction are observed from two-dimensional (2D) photonic crystal slab structures. However, the problem, of surface recombination due to large surface-to-volume ratio still remains to be addressed. In this work, we present the analysis of nonradiative recombination effects on the optical characteristics of InGaAsP-based air-hole photonic crystal light-emitting structures.

Quasi-Continuous Operation of 1.55- μm Vertical-Cavity Surface-Emitting Lasers by Wafer Fusion

Room temperature quasi-continuous operation is achieved near 1556 nm with threshold current as low as 2.2 mA from a 5.6-

Room temperature continuous operation of optically-pumped two-dimensional photonic crystal slab laser

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