R. H. Yan

Electrically tunable Fabry-Perot mirror using multiple quantum well index modulation

We describe a novel surface normal Fabry–Perot multiple quantum well index reflection modulator which may be tuned electrically. The Fabry–Perot etalon, composed of two AlAs/Ga1−xAlxAs quarter‐wavelength grating mirrors separating a multiple quantum well GaAs/Ga1−xAlxAs active medium, is formed in a single growth by molecular beam epitaxy. Contrast ratios of up to 8:1 at 873 nm have been measured.

A tanh substitution technique for the analysis of abrupt and graded interface multilayer dielectric stacks

The authors report a new analytical technique for estimating the peak reflectivity of lossless dielectric stacks with combinations of quarter and/or half-wave thicknesses. A simple variable substitution is used to transform the standard formula for the reflectivity of a Fabry-Perot resonator into a remarkably simplified form. The resulting expressions for reflectivity are intuitively appealing, allowing use of additive algebra to calculate the peak reflectivity of a multilayer dielectric stack. >

Design of optimized high‐speed depletion‐edge‐translation optical waveguide modulators in III‐V semiconductors

A new first‐principle theory that includes the higher order field and carrier effects in semiconductor waveguide refractive index modulators has been developed. For the first time, the relative importance of the electrorefractive, band filling, linear electro‐optic, and plasma effects is shown. The theory agrees well with measurements from experimental AlGaAs/GaAs depletion‐edge‐translation (DET) phase modulators that have given record levels of phase shift per volt per unit length, and it suggests an improved DET device design with much larger phase shifting efficiency. The required drive voltage/bandwidth figure of merit, Vπ/ Δf, for this configuration (without including quantum wells) is lower than for any other existing optical index modulator.

Multi-quantum well electro-optic modulator using a combination of excitonic index and absorption changes

Efficient reflection modulation, using index and absorption changes in a novel p-i-n surface-normal Fabry-Perot resonator configuration, is reported. A reverse bias changes both the absorption and the index of refraction by a tuning of the exciton resonance. In the resonator configuration, these effects cause both a shift in the position of the Fabry-Perot modes and a change in its Q, which can combine to enhance the net change in modulator reflectivity near the exciton lines. Further away from these exciton lines, the Fabry-Perot modes tune purely by index modulation. >