Intrinsic parameter and modal characteristics of asymmetric cladding ridge waveguide lasers

Deep-Etched Native-Oxide-Confined High-Index-Contrast AlGaAs Heterostructure Lasers With 1.3 $\mu$m Dilute-Nitride Quantum Wells

“…In particular, HIC waveguides typically suffer greatly from scattering loss, shown to be inversely proportional to waveguide width to the fourth power (∝ 1/w 4 ) at the same roughness level [13]. Price et al have recently studied the mode confinement and loss mechanism of conventional index-guided lasers by varying the shallow etch depth in the upper cladding layers [24] and observed a more than 4 × loss increase from 5 cm −1 to about 21 cm −1 on the best w = 3 µm devices (∆n = 0.004) when the etch stops at 400 and 100 nm above the GaAs waveguide core layer, respectively. The fast increase of the loss is attributed to the scattering from the interaction of the optical mode with etch imperfections [24], indicating the strong effect of scattering loss even on conventional index-guided narrow-stripe devices of fairly low lateral index contrast.…”

“…Price et al have recently studied the mode confinement and loss mechanism of conventional index-guided lasers by varying the shallow etch depth in the upper cladding layers [24] and observed a more than 4 × loss increase from 5 cm −1 to about 21 cm −1 on the best w = 3 µm devices (∆n = 0.004) when the etch stops at 400 and 100 nm above the GaAs waveguide core layer, respectively. The fast increase of the loss is attributed to the scattering from the interaction of the optical mode with etch imperfections [24], indicating the strong effect of scattering loss even on conventional index-guided narrow-stripe devices of fairly low lateral index contrast. Although the total laser internal modal loss is composed of not only waveguide scattering loss but also material and free carrier absorption losses, the very low total waveguide loss seen in Fig.…”

Nonselective oxidation of GaAs-based III-V compound semiconductor heterostructures for in-plane semiconductor lasers

“…Numerous approaches to device structure optimization have been demonstrated to minimize current spreading, including varying the residual upper cladding thickness (i.e., etch depth) [15,22] and utilizing a buried heterostructure [23]. It is obvious that a reduced residual upper cladding layer thickness improves the lateral carrier confinement, however, ~3-4 higher optical scattering loss is also typically observed [22] since the guided light interacts with the waveguide sidewall roughness more intensely.…”

“…It is obvious that a reduced residual upper cladding layer thickness improves the lateral carrier confinement, however, ~3-4 higher optical scattering loss is also typically observed [22] since the guided light interacts with the waveguide sidewall roughness more intensely. Higher internal optical loss plus the probable extension of etch defects into the active region consequently leads to an overall higher threshold current [22].…”

“…It is obvious that a reduced residual upper cladding layer thickness improves the lateral carrier confinement, however, ~3-4 higher optical scattering loss is also typically observed [22] since the guided light interacts with the waveguide sidewall roughness more intensely. Higher internal optical loss plus the probable extension of etch defects into the active region consequently leads to an overall higher threshold current [22]. A buried heterostructure employing an etch plus regrowth process to confine the etch-defined p-waveguide region by an adjacent regrown n-cladding material has been shown to reduce the current spreading through reverse biasing of the n-cladding/p-waveguide diode junction.…”