Browsing by Author "Tai, K"

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Alterable temperature-dependent wavelength shifts in (InP)(2)/(GaP)(2) quantum wells
(1998-02-02)
Cheng, YC
;
Tai, K
;
Chou, ST
;
Huang, KF
;
Tu, SL
Alterable temperature-dependent emission wavelength shifts were observed from (InP)(2)/(GaP)(2) short-period superlattices (SPSs) quantum wells grown with different interruption periods. Photoluminescence spectra showed that the peak energy of the SPS samples is inversely proportional to the interruption time conducted between the two consecutive binary growth sequences in the SPS regions. It is believed that a lateral composition modulation occurred during the interruption period which resulted in periodic In-rich and Ga-rich regions in the SPS quantum wells along the growth plane. With the lateral compositional variation, temperature variation can induce a multiaxial strain effect which can either amplify or reduce the temperature-dependent wavelength shift of the SPS quantum wells with different interruption periods. (C) 1998 American Institute of Physics.
AuBe Ohmic contacts to p-type ZnTe
(1998-12-10)
Lan, WH
;
Lin, WJ
;
Cheng, YC
;
Tai, K
;
Tasi, CM
Ohmic contacts of AuBe to p-ZnTe show a minimum specific contact resistance of 3.0 x 10(-6) Ohm cm(2) for a p-doping level of 1.6 x 10(19) cm(-3) and at an annealing temperature of 200 degrees C. The beryllium is very effective at improving the electrical properties of p-type contacts to ZnTe.
Far-field emission narrowing effect of microdisk lasers
(1998-05-04)
Lee, TD
;
Cheng, PH
;
Pan, JS
;
Tsai, RS
;
Lai, Y
Far-field intensity distribution of semiconductor microdisk lasers is experimentally measured and the emission angle is found to be much smaller than that of a planar source with the same near-held width. In fact the emission angle is determined mainly by the disk radius instead of the disk thickness. A scalar diffraction theory in the cylindrical coordinate is developed to explain such an emission-angle-narrowing phenomenon and numerical calculation based on a vectorial diffraction theory is carried out to explain the measured polarization state. (C) 1998 American Institute of Physics.
Mode emission characteristics of semiconductor microdisc and microring lasers
(1996-10-01)
Lee, TD
;
Cheng, PH
;
Pan, JS
;
Tai, K
;
Lai, Y
We fabricate both microdisc and microring InGaAsP-InGaAs quantum well semiconductor lasers using an etching-and-bonding technique. Their emission properties are studied by optical pumping at 77 K. Single mode lasing is achieved for discs with a diameter of 5 mu m. Multimode emission is observed for rings with larger diameters. Both fundamental and higher order lasing modes are observed and are found to exhibit interesting emission characteristics.
Mode emission properties of semiconductor micro-disk and micro-ring lasers
(1999)
Lee, TD
;
Cheng, PH
;
Pan, JS
;
Tai, K
;
Lai, Y
We have successfully fabricated optically pumped semiconductor micro-disk and micro-ring lasers under the InGaAsP/InGaAs system at the 1.5 mu m wavelength and under the InGaP/InGaAlP system at the 0.66 mu m wavelength. The spontaneous emission factor beta of these micro-lasers is estimated directly from their output-pump curves and its dependence on the cavity volume is verified. Interesting phenomena regarding the far-field emission pattern and lasing linewidth of these micro-cavity lasers are experimentally observed and theoretically studied.
Spontaneous emission factor versus cavity volume in low dimensional photonic micro-cavities
(1997-10-15)
Cheng, PH
;
Lee, TD
;
Pan, JS
;
Lai, Y
;
Tai, K
Micro-ring and micro-disk lasers an formed at the same time by transferring the epitaxial layers of 1.55 mu m wavelength InGaAs/ZnGaAsP quantum wells on a glass substrate. The spontaneous emission factor beta in such micro-rings of 5 mu m diameter and 0.2 x 0.5 mu m(2) cross-section is 0.16, which is four times that in micro-disk lasers of the same diameter. The result confirms for the first time that the micro-ring being a lower dimensional photonic system has a larger beta. Study of beta versus the cavity size indicates that the observed spontaneous emission factor is approximately the reciprocal of the normalized cavity volume, when normalization is done to the cubic of the wavelength in the medium. (C) 1997 Elsevier Science B.V.
Spontaneous emission factor versus cavity volume in low dimensional photonic micro-cavities
(1997-10-15)
Cheng, PH
;
Lee, TD
;
Pan, JS
;
Lai, Y
;
Tai, K
Micro-ring and micro-disk lasers an formed at the same time by transferring the epitaxial layers of 1.55 mu m wavelength InGaAs/ZnGaAsP quantum wells on a glass substrate. The spontaneous emission factor beta in such micro-rings of 5 mu m diameter and 0.2 x 0.5 mu m(2) cross-section is 0.16, which is four times that in micro-disk lasers of the same diameter. The result confirms for the first time that the micro-ring being a lower dimensional photonic system has a larger beta. Study of beta versus the cavity size indicates that the observed spontaneous emission factor is approximately the reciprocal of the normalized cavity volume, when normalization is done to the cubic of the wavelength in the medium. (C) 1997 Elsevier Science B.V.