Investigation of terahertz emission characteristics of coherent InAs/InGaAs quantum-dash and quantum-dash-in-a-well
Abstract
The terahertz (THz) generation of molecular beam epitaxy (MBE) grown quantum dash (Qdash) and quantum dash-in-a-well (DWELL) were assessed through THz-Time-Domain Spectroscopy (TDS) measurements in reflection geometry. Samples were optically pumped using a 1550nm wavelength femtosecond laser, and detected using an optically gated photoconductive antenna (PCA). The measured peak-to-peak difference THz signal values for samples Qdash-1, Qdash-2, and DWELL were 11 pA, 13 pA, and 6 pA, respectively. Fast Fourier Transform (FFT) power spectra revealed that the center of frequency of the samples were 0.72 THz for Qdash-1, 0.72 THz for Qdash-2, and 0.65 THz for DWELL. Moreover, The differences in observed signals between Qdashes and DWELL were demonstrated, and was attributed to variations in carrier lifetime from different samples. Additionally, differing degree carrier confinement in Qdashes and DWELL were discussed in relation to THz generation capability.