Refractive-index nonlinearities of intersubband transitions in GaN/AlN quantum-well waveguides

Abstract

The refractive-index nonlinearities of intersubband transitions in GaN/AlN quantum-well waveguides are investigated. A large spectral broadening of TM-polarized near-infrared pulses is observed after propagation through these devices due to intersubband self-phase modulation. From the measured data, a nonlinear refractive index n 2 of 1.8ϫ 10 −12 cm 2 / W is estimated at the operating wavelength of 1550 nm. A detailed theoretical model of the intersubband refractive index as a function of wavelength and optical intensity is then presented. This model assumes an inhomogeneously broadened transition line and is based on experimentally determined material and device parameters. The results of this study are finally used to discuss the prospects of nitride quantum wells for all-optical switching via cross-phase modulation.

Measuring the refractive index around intersubband transition resonance in GaN/AlN multi quantum wells

“…The theoretical work of Cen et al [15] describes the influence of polarization induced electric fields on the resonance wavelength and the refractive index of ISBTs in GaN/AlN coupled QWs. Refractive index nonlinearities in GaN/AlN QWs were studied by Lin et al [16]. In a recent work, Lupo et al [17] reported a measurement of Δn ISBT deduced from the shift of the position of the beating interference maxima of different order modes in a wave-guided depletion modulator.…”

Nonlinear absorption of InN/InGaN multiple-quantum-well structures at optical telecommunication wavelengths

“…Therefore, throughout the InN layer thickness, edge-type threading dislocations keep a uniform density in the range of mid 10 9 cm -2 [8]. It must be pointed out that GaN-based waveguide devices with similar density of threading dislocations have been reported [2], [3].…”

“…Optical switching based on intersubband transitions in GaN/AlN nanostructures operating at 1.5 μm has been reported [2] [3].…”

Intersubband absorption in Si‐ and Ge‐doped GaN/AlN heterostructures in self‐assembled nanowire and 2D layers

“…On the other hand, ISB transitions in planar GaN/AlN quantum wells are extensively studied [17], [18], with many devices being developed [19][20][21][22][23], typically based on Sidoping. It is interesting at this point to explore the development of Ge doping for the same tasks.…”