Ultrafast intersubband optical switching in II–VI‐based quantum well for optical fiber communications

Abstract

Abstract Ultrafast all‐optical switching at optical communication wavelength has been investigated by utilizing an intersubband transition (ISBT) of II–VI‐based multiple quantum wells (MQWs) fabricated in high‐mesa waveguide devices. At first, we have achieved λ ∼ 1.55 µm ISBT absorption in (CdS/ZnSe)/BeTe QWs. The QWs consists of Cl‐doped CdS/ZnSe well and BeTe barrier. The ISBT optical nonlinearity in the wafer sample exhibits sub‐ps relaxation time and sub‐pJ/µm 2 saturation energy, indicating a promising characteristic for high‐speed switching. The waveguide device fabricated consists of a CdS/ZnSe/BeTe MQWs core layer and two top and bottom ZnMgBeSe quaternary cladding layers. Ultrafast gate switching within a time window of 0.56 ps was demonstrated with pump pulse at λ = 1.57 µm and probe pulse at λ = 1.63 µm in this waveguide device. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)