Low threshold InGaAsP/InP lasers with microcleaved mirrors suitable for monolithic integration

Low threshold InGaAsP/InP injection lasers on semi-insulating InP substrates have been developed with mirrors fabricated by the microcleavage technique. Miniature suspended bridges containing the laser channels have been formed and then microcleavage has been accomplished by the use of ultrasonic vibrations. Lasers with current thresholds as low as 18 mA with 140-µm cavity length and with 35–45% differential quantum efficiency have been obtained

Mode stabilized terrace InGaAsP lasers on semi-insulating InP

Mode stabilized terrace InGaAsP lasers have been fabricated on semi-insulating InP substrates. The fabrication involves a selective, single-step liquid phase epitaxial growth process, and a lateral Zn diffusion. Two versions of the terrace lasers are fabricated, and threshold currents as low as 35 mA and 50 mA respectively are obtained. The lasers operate with a stable single lateral mode. High power performance is observed. These lasers are suitable for monolithic integration with other optoelectronic devices

Phase-locked InGaAsP laser array with diffraction coupling

A phase-locked array of InGaAsP lasers has been fabricated for the first time. This 50-µm-wide array utilized diffraction coupling between adjacent lasers to achieve phase locking. Threshold current as low as 200 mA is obtained for arrays with 250-µm cavity length. Smooth single-lobe far-field patterns with beam divergence as narrow as 3° have been achieved

A Bayesian test for the appropriateness of a model in the biomagnetic inverse problem

This paper extends the work of Clarke [1] on the Bayesian foundations of the biomagnetic inverse problem. It derives expressions for the expectation and variance of the a posteriori source current probability distribution given a prior source current probability distribution, a source space weight function and a data set. The calculation of the variance enables the construction of a Bayesian test for the appropriateness of any source model that is chosen as the a priori infomation. The test is illustrated using both simulated (multi-dipole) data and the results of a study of early latency processing of images of human faces. [1] C.J.S. Clarke. Error estimates in the biomagnetic inverse problem. Inverse Problems, 10:77--86, 1994.Comment: 13 pages, 16 figures. Submitted to Inverse Problem

Direct measurement of the carrier leakage in an InGaAsP/InP laser

Carrier leakage over the heterobarrier in an InGaAsP/InP laser is measured directly in a laser-bipolar-transistor structure. Experimental results indicate a significant amount of carrier leakage under normal laser operating conditions