Controlling Third-Order Nonlinearities by Ion-Implantation Quantum-Well Intermixing

Abstract

Abstract-The optical Kerr effect was measured by observing self-phase modulation in GaAs-AlGaAs superlattice-core waveguides modified by ion-implantation quantum-well intermixing. The band-gap energy was shifted by 68 nm for an implantation dose of 0 5 10 13 cm 2 and annealing temperature of 775 C. The Kerr effect was suppressed by up to 71% in the transverse-electric polarization after intermixing. A reduced polarization dependence of the self-phase modulation was observed after intermixing.Index Terms-Nonlinear optics, optical Kerr effect, quantumwell intermixing (QWI), semiconductor superlattice. COMPOUND semiconductors have led the way towards monolithically integrated all-optical signal processing devices. Mature fabrication technologies have allowed the development of low-loss waveguides and advanced structures such as Bragg reflection waveguides [1], passive mode converters [2], and cascaded microring resonators [3]. AlGaAs is of particular interest since the optical Kerr effect, a third-order nonlinearity, has been shown to be 500 times stronger than in silica [4]. These nonlinearities are nonresonant and do not rely on free-carrier plasma dispersion effects since the operating wavelengths are typically below the half-band-gap energy. This has opened the possibility of all-optical switching devices such as nonlinear directional couplers (NLDCs) [5] and nonlinear Mach-Zehnder interferometers (NLMZIs) [6] with ultrafast response times necessary for ultrahigh-speed communications systems and signal processing. Multiple quantum-well (MQW) structures based on AlGaAs permit greater flexibility to tailor the band-gap energy to suit the optical properties required for particular applications. Furthermore, the band-gap energy of MQWs can be modified after wafer growth by quantum-well intermixing (QWI) techniques [7]. This cost-effective approach allows selective control , which is a requirement for devices such as QPM gratings. Deep-well semiconductor superlattices have attracted attention as the greater fill-factor and large band discontinuity in comparison to conventional quantum-well structures potentially provides a larger modification to nonresonant optical properties such as the refractive index and nonlinear optical susceptibilities in the transparency window for the complete structure. Thus, shorter and more efficient devices that require less power to operate are possible. In this letter, we demonstrate large modifications of the optical Kerr effect in GaAs-AlGaAs superlattice-core waveguides induced by ionimplantation QWI at wavelengths near the half-band-gap. We have previously reported on the large polarization dependence of the Kerr coefficient in GaAs-AlAs superlattice waveguides [12]. However, measurements indicated the presence of parasitic two-photon absorption (TPA) resonances due to the reduced barrier resulting in asymmetric quantum wells (ASQW) found on either side of the superlattice waveguide core. In the present study, we modified the waveguide structure with several improvements. The new ...

Stable integrated hyper-parametric oscillator based on coupled optical microcavities

“…Notice that the resulting round-trip time in the cavity is still much shorter than the lifetime, thus Ikeda instabilities would require power and detuning values incompatible with the present analysis. The medium is a semiconductor of refractive index 3.48, Kerr index n 2 = 2 × 10 −17 m 2 /W [22], thus we getχ = 2.90 × 10 22 [Js] −1 . The scaling intensity results I 0 = 34.4 fJ.…”

Recent advances in phase matching of second‐order nonlinearities in monolithic semiconductor waveguides

“…This allows pump lasers to be mixed with passive optical components. However, the intermixing process has also been shown to alter the nonlinear optical properties of the quantum well structure [69]. Furthermore, the absorption/emission band and nonlinear strength can be manipulated with varying degrees of intermixing on the same chip [70], opening the possibility of monolithic integration of complex photonic integrated circuits and systems.…”

“…We also eliminated a pair of AQWs by terminating the superlattice at either end with barrier layers of Al 0 85 Ga 0 15 As instead of well layers of GaAs. This removed a parasitic two-photon absorption peak present in the original wafer design [69]. Secondly, the IID and RTA processes were optimized to provide an appropriate balance between optical losses and bandgap shift.…”

Study of N ions implantation induced quantum well intermixing in GaInP/AlGaInP quantum well structures

“…However, ion implantation has adverse influence on the crystal quality, and the caused damage should be improved by the optimized annealing parameters to meet the demand of device fabrication. Many ions such as P [10], As [11], He [12], and H [13] can be applied in the ion implantation induced QWI. Whereas P and As are commonly used given preference to their impurity-free M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT introduction, their low diffusion coefficient can result in irreparable implantation damage, which may degrade the device performance [12].…”

“…However, ion implantation has adverse influence on the crystal quality, and the caused damage should be improved by the optimized annealing parameters to meet the demand of device fabrication. Many ions such as P [10], As [11], He [12], and H [13] can be applied in the ion implantation induced QWI. Whereas P and As are commonly used given preference to their impurity-free…”