Lynn C. Calhoun

Mechanical property measurement of InP-based MEMS for optical communications

We investigate mechanical properties of indium phosphide (InP) for optical micro-electro-mechanical systems (MEMS) applications. A material system and fabrication process for InP-based beam-type electrostatic actuators is presented. Strain gradient, intrinsic stress, Young’s modulus, and hardness are evaluated by beam profile measurements, nanoindentation, beam bending, and electrostatic testing methods. We measured an average strain gradient of δe0/δt = 4.37 × 10 −5 m −1 , with an average intrinsic stress of σ0 =− 5. 4M Pa for [0 1 1] beams. The intrinsic stress results from arsenic contamination during molecular beam epitaxy and (MBE) can be minimized by careful MBE growth and through the use of stress compensating layers. Nanoindentation of (1 0 0) InP resulted in E = 106. 5G Pa and H = 6.2 GPa, while beam bending of [0 1 1] doubly clamped beams resulted in E = 80.4 GPa and σ0 =− 5.6 MPa. We discuss the discrepancy in Young’s modulus between the two measurements. In addition, we present a method for simultaneously measuring Young’s modulus and residual stress using beam bending. Electrostatic actuation in excess of 20 V is demonstrated without breakdown.

Monolithic suspended optical waveguides for InP MEMS

We present a novel waveguide design for InP microelecromechanical systems. The substrate is removed from underneath the waveguide by sacrificial etching, and the suspended waveguide is supported by lateral tethers. This allows segments of the waveguide to be moved and prevents substrate leakage loss in the fixed segments of the waveguides. A single-mask fabrication process is developed that can be extended to more complex devices employing electrostatic actuation. Fabricated suspended waveguides exhibit a loss of 2.2 dB/cm and tether pairs exhibit 0.25-dB additional loss.

A tunable GaInAsP-InP optical microring notch filter

The authors demonstrate an ultracompact tunable GaInAsP-InP microring notch filter. The core of the device is a quantum-well superlattice and forms the intrinsic region in a p-n structure. The device has curved sections of radius 2.25 /spl mu/m and straight sections of length 1 /spl mu/m, making it the smallest microring filter ever reported. They obtain 0.8 nm (100 GHz) of tuning by reverse-biasing the diode structure over 8 V using the quadratic electrooptic effect.

Piezoelectric Al

This paper reports the modeling, fabrication, and experimental characterization of piezoelectric longitudinal mode bar resonators based on thin film single crystal Al/sub 0.3/Ga/sub 0.7/ As. Fabricated resonators with lengths ranging from 1000 /spl mu/m to 100 /spl mu/m have been characterized for operation in their first five odd longitudinal modes. Resonance frequencies range from 2.5 to 75 MHz, with quality factors up to 25 390 at 21.8 MHz in vacuum. Power handling capacity as high as -2.6 dBm is demonstrated at 18.8 MHz. Motional resistance and temperature stability of the resonators are also evaluated.

_0.3

Single transverse mode vertically coupled semiconductor microring resonators were made using a novel fabrication technique without regrowth. GaAs-AlGaAs and GaInAsP-InP devices are demonstrated.

Ga

This study demonstrates and characterizes the performance of all-optical AND and NAND logic gates using InP and GaAs micro-racetrack resonators. Since the switching energy of the device scales down by field enhancement (FE), subpico joule switching energy is predicted, which is required to operate the logic gate at 100 GHz assuming a carrier lifetime of 10 ps and that the microresonator has a moderate FE of 4.

_0.7

This paper demonstrates electro-optic tuning of a laterally-coupled GaInAsP-InP micro-ring resonators. The device is a p-i-n diode, with the intrinsic region of forming the waveguide core. The intrinsic region is composed of a superlattice of quantum wells. By applying a reverse bias, the resonance wavelength is tuned by 0.8 nm (100 GHz) over 8 V using the quadratic electro-optic effect. The quadratic electro-optic coefficient is estimated to be 4.9 /spl times/ 10/sup -15/ cm/sup 2//V/sup 2/. Independent measurements of the electro-optic characteristics of the wafer is also presented.

As Longitudinal Mode Bar Resonators

Summary form only given. Our work on periodically-coupled, triple-microring-resonator channel dropping filters in GaAs-AlGaAs and GaInAsP-InP is based on our prior fabrication efforts in these systems We demonstrate high-order filtering, bandpass flattening and improved free spectral range. Their behavior is consistent with theoretical analysis of such devices we have demonstrated vernier effect, and high-order filtering in triple-ring parallel cascaded filters.