Modeling of Active Layer and Injection-locking Characteristics inPolarized and Unpolarized Fabry-Perot Laser Diodes (Received January 6, 2012; Revised manuscript February 14, 2012; Accepted February 14, 2012) In this paper, injection-locking characteristics versus active layer structures in Fabry-Perot laser diodes (FP-LD) are compared. TE and TM gain spectra and peak gains versus carrier density in polarized and unpolarized multiple quantum well structures and in an unpolarized bulk structure are calculated. The calculated gain parameters are applied to a time-domain large-signal model to simulate the injection-locking characteristics. The results show that RIN in unpolarized FD-LDs is about 3 dB lower than that in a polarized FP-LD and that the eye characteristics of the unpolarized FP-LD are much better than those of the polarized FP-LD.
The dependence of leakage current in a planar buried heterostructure laser diode (PBH-LD) on the operating temperature was analyzed by taking the effects of the connection width between a p-InP clad layer and a p-InP blocking layer into account. A two-step etching process comprising nonselective mesa etching followed by InP selective etching is proposed for obtaining a narrow connection width and high controllability of an active layer width. The performance was compared for LDs fabricated using the two-step etching process and those fabricated using conventional nonselective etching process. The average threshold current and the slope efficiency of the 1.3 µ m strain-compensated multiple quamtum well (MQW) PBH-LD fabricated using the two-step etching process were 5.6 mA and 0.27 mW/mA, respectively, for a cavity length of 400 µ m. However, using the nonselective etching process, the average threshold current was 14.5 mA and the slope efficiency was 0.22 mW/mA, given the same cavity length. A higher differential gain and characteristic temperature were also obtained due to the lower leakage currents and strain-compensated multiple quantum well active layers.
An InAsP phase formed during the heatup time to the growth temperature of MOVPE was investigated by transmission electron microscopy and energy dispersive spectroscopy. The thickness of the InAsP phase on the concave regions of corrugation is increased with increased AsH3 partial pressure and heat-up time. The arsenic composition in InAsP was also increased with the increase of AsH3 partial pressure during the heat-up time. Dislocations and defects were not generated below an AsH3 partial pressure of 2.4×10−3 Torr, although strain was induced according to the thickness and composition of InAsP formed on the concave regions of corrugation.
The silicon (Si) or boron (B) implantation process in
Ga0.8In0.2As/Ga
x
In1-x
As
y
P1-y
/Ga0.51In0.49P/GaAs
quantum well structures can be used not only for maintaining
single lateral mode during high power operation but also for
increasing the catastrophic optical damage (COD) level of 980 nm pump
lasers. The fabricated 980 nm pump lasers with partially ion
implanted channels after ridge waveguide structure formation exhibited
high power operation up to 250 mW without any kink and
beam steering. A photoluminescence peak shift of 70 meV was
obtained by 120 keV Si-implantation and annealing at
900°C. Improvement of the COD level by
a minimum of 1.65 times is obtained by forming transparent windows
near facets
by Si implantation and annealing. A highly nonradiative polycrystalline phase of the active area may be the major cause of COD failure in the Al-free 980 nm lasers.
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