Quantum Interference Control (QuIC) of Currents in Semiconductors

Abstract

This dissertation presents the first comparison of the polarization dependence of the photocurrents generated in 1+2 QuIC and 2+3 QuIC. We also show the first observation of 1+2 QuIC current from Ohmic-contact AlGaAs devices. We demonstrate that the optical frequency combs (OFC) are capable of providing a two-color light field with a controllable relative phase, which is vital to 2+3 QuIC generation. The feed-forward technique is effective in reducing the bandwidth of the offset frequency and offers tunability to the detection frequency of 2+3 QuIC.

We first discuss our results from the 1+2 QuIC setup. We generate 1+2 QuIC photocurrent from AlGaAs devices, which have two types of metal-semiconductor contact - Schottky contact and Ohmic contact. We detect the QuIC currents at the dither frequency of one of the arms of the two-color interferometer. We show that the oscillation of the relative phase results in the oscillation of QuIC current. The amplitude of the QuIC current responds to the oscillations of both optical arms. The QuIC current from the Ohmic-contact AlGaAs device has a more linear external-resistance dependence than that from the Schottky-contact AlGaAs device, which indicates a current source nature of the Ohmic-contact QuIC device.

We then discuss our results on the 2+3 QuIC current, which is detected at a phase ramp directly related to the offset frequencies of two OFCs. We present the detection-frequency dependence of 2+3 QuIC current, which validates the bandwidth reduction of the offset frequencies. The sinusoidal dependence of 2+3 QuIC current on the optical path delay is consistent with the optical injection theory.

We finally show the QuIC currents measured from two perpendicular Ohmic-contact electrode pairs in 1+2 QuIC and 2+3 QuIC. We observe the change of QuIC currents when two co-linearly polarized light fields rotate together. The fitting of experimental data with an angular current density model shows evidence for the k-space localization of 2+3 QuIC. We also extract the injection rate tensor elements from one-color polarization dependencies of 1+2 QuIC and 2+3 QuIC. Our study shows the potential of 2+3 QuIC as a tool for high k-space-resolution band anisotropy studies.