We present a simple, accurate, and fast algorithm for solving the one-dimensional time-independent Schrodinger equation. The algorithm is based on the transfer matrix method. We can thus calculate all bound and quasi-bound energy levels and the corresponding wave functions for an arbitrarily shaped potential profile. The results of our calculations are compared with those obtained by other authors for various types of problems. A central part of this paper deals with the solving of the Schrodinger equation in quantum-well structures. Our results show that the transfer matrix method is as accurate as other methods, but it is easier to implement and, hence, is superior for calculations on small computers, such as a PC.

Abstract-We report on extended measurements and theory on the recently developed monolithic wavelength demultiplexer consisting of voltage tunable superlattice p-i-n photodetectors in a waveguide configuration. This includes a reduced wavelength spacing, an investigation of the polarization dependence of the crosstalk and bit-error-rate measurements for various crosstalk levels. We show that the device is able to demultiplex and detect two optical signals with a wavelength separation of 20 nm directly into different electrical channels at a data rate of 1 Gbit/s and with a crosstalk attenuation varying between 20 and 28 dB, depending on the polarization. The minimum acceptable crosstalk attenuation at a data rate of 100 Mbits/s is determined to be 10 dB. The feasibility of using the device as a polarization angle sensor for linearly polarized light is also demonstrated. The paper includes a theory for the emission of photogenerated carriers out of the quantum wells since this is potentially a speed limiting mechanism in these detectors. We show that a theory of thermally assisted tunneling by polar optical phonon interaction is able to predict emission times consistent with the observed temporal response.

Widely tunable single-mode picosecond pulses have been obtained from a buried optical guide AlGaAs semiconductor laser operated with external grating feedback. Intensity autocorrelation measurements show single-mode 30-ps pulses. A tuning range of 20 nm, corresponding to more than 70 different laser frequencies, was easily achieved.

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