The effect of temperature on carrier induced refractive index change of InGaAs/InGaAsP quantum wells is investigated, which shows that a reasonable adjustment of well width and carrier concentration can improve temperature dependence of index change.

No abstract

Characteristics of polarization insensitivity of carrier-induced refractive index change of 1.55 μm tensile-strained multiple quantum well (MQW) are theoretically investigated. A comprehensive MQW model is proposed to effectively extend the application range of previous models. The model considers the temperature variation as well as the nonuniform distribution of injected carrier in MQW. Tensile-strained MQW is expected to achieve polarization insensitivity of carrier-induced refractive index change over a wide wavelength range as temperature varies from 0°C to 40°C, while the magnitude of refractive index change keeps a large value (more than 3 × 10^-3). And that the polarization insensitivity of refractive index change can maintain for a wide range of carrier concentration. Multiple quantum well with different material and structure parameters is anticipated to have the similar polarization insensitivity of refractive index change, which shows the design flexibility.

A novel technique is presented in obtaining the performance characteristics of traveling-wave semiconductor optical amplifier (TWA) with tensile-strained-barrier multiple-quantum-well structure. In-out fiber ends of TWA are used to construct an external cavity resonator to produce big ripple on amplified spontaneous emission (ASE) spectrum. By this means, Hakki-Paoli method is adopted to obtain gain and differential gain spectra over a wide spectral range. From measured longitudinal mode spacing and peak wavelength shift due to increased bias current, we further calculate the effective refractive index, carrier-induced refractive index change and linewidth enhancement factor. Some special features about ASE mode spectrum shift and refractive index change above lasing threshold are revealed and explained.

The influences of dot material component, barrier material component, aspect ratio and carrier density on the refractive index changes of TE mode and TM mode of columnar quantum dot are analyzed, and a multiparameter adjustment method is proposed to realize low polarization dependence of refractive index change. Then the quantum dots with low polarization dependence of refractive index change (<1.5%) within C-band (1530 nm - 1565 nm) are designed, and it shows that quantum dots with different material parameters are anticipated to have similar characteristics of low polarization dependence.