ABSTRACT
Vertical cavity surface emitting lasers (VCSELs) emitting from 1.3 to 1.55 pm is considered as one of key components to realize high-speed optical local area networks and metro networks. However, conventional long wavelength lasers such as GalnAsP grown on an InP substrate have poor temperature characteristics due to their poor electron confinement. Long wavelength material, which can be grown on a GaAs substrate are very attractive, because the same structure can be used such as GaAs-based VCSELs including AlGaAs/GaAs distributed Bragg reflectors (DBRs) and a selectively oxidized AlAs current confinement structure [1][2]. A GalnNAs alloy was proposed as a novel material for long wavelength lasers grown on a GaAs substrate [3]. It is expected to show excellent temperature characteristics due to its large conduction band offset [4-6]. The bandgap energy of GalnNAs is decreased by small increase of the nitrogen composition due to a large bandgap bowing of the GalnNAs system. As a result, a photoluminescence (PL) up to 1.55 pm wavelength range was reported by a GalnNAs on a GaAs substrate [7], which indicates a capability of 1.55 pm GalnNAs lasers. The improvement in crystal qualities is a critical issue for increasing the nitrogen composition. There have been much effort to improve the crystal quality for molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) growths. 1.3 pm range GalnNAs/GaAs edge emitting lasers are succeeded in decreasing threshold current density as low as conventional GalnAs/GaAs QWs lasers [5][6][8-12]. Also GalnNAs/GaAs VCSELs emitting at 1.2-1.3 pm range have been reported [13-17]. However there are only a few reports on GalnNAs/GaAs lasers emitting beyond 1.3 pm of the wavelength [9] [18]. Capability of GalnNAs lasers such as excellent temperature characteristics and VCSELs will become also important for the wavelength range of 1.55 pm for a low-loss optical fiber window and 1.48 pm for the erbium doped fiber amplifier (EDFA) pumping.
