| We present a discussion of waveguide phase modulators designed to be compatible with GaAs opto-electronic integrated circuit (OEIC) technology. Such compatibility introduces three special requirements: small size (which is directly related to cost), low drive voltage, and low growth and processing temperatures. In our discussion, we also address the frequency response of such a device.; We begin by reviewing the physical mechanisms and figures of merit for bulk and quantum well (QW) waveguide phase modulators in the current literature so that performance comparisons can be made. We also present experimental measurements of all-binary (InAs/GaAs) /GaAs MQW p-i-n waveguide modulators.; We optimize the electric field and optical confinement in order to maximize the phase change for a given applied voltage and device length. We consider a so-called hetero-nipi structure, since it is a more general case than a p-i-n, and take as our variable parameters the thicknesses of the doped regions, the doping concentrations, the number of intrinsic regions, the compositions of any cladding layers, and the thicknesses of the i regions. We give an algorithm for the optimization process and use it to design a structure. Due to depletion effects, there is an optimum intrinsic region thickness for a given set of parameters. We design a waveguide capable of achieving a {dollar}pi{dollar} phase change with 3 V applied over a 300 {dollar}mu{dollar}m length that also meets OEIC temperature requirements.; The geometry of the nipi structure changes the circuit model of the device, adding extra resistance and capacitance, and we analyze the impact of this on frequency response.; Finally, we have fabricated and characterized several devices based on this design, and the results show good agreement with predictions. We are able to achieve a {dollar}pi{dollar} phase change with 0.62 V applied in a 1.24 mm long device with a frequency response of 110 MHz. This corresponds to a V{dollar}sb{lcub}pi{rcub}{dollar} x L product of 0.77 V mm, which scales to a {dollar}pi{dollar} phase change at 3.1 V with a critical frequency near 200 MHz for a device length of 300 {dollar}mu{dollar}m. |
