THz applications of multimode laser diodes: a review

Abstract

Investigations are ongoing to develop cheaper THz time-domain spectroscopy (THz-TDS) systems. In thiscontext, many studies have been published in which multimode laser diodes (MLDs) are used as light sources in THz-TDS systems. There is another method for cost-reduction. Photomixing employs two single-mode LDs and does notrequire a pulse laser, and then realizes a reduced-cost system. A comprehensive report has been presented by examiningthe work done up to now. In these studies, it has been shown that the characteristics of MLDs, the effects of antennastructures on THz signal production, the difficulty of collimation of the MLD radiation beam, and the contribution offiber-based systems are of utmost importance. It has also been determined that mode spacing has a significant role inTHz radiation generation. In addition, successful SN ratio enhancement and imaging studies have shown that a morecompact and cheaper THz-TDS system can be established using MLDs as a light source. Macor and RC51HF sampleshave been analyzed using a MLD-TDS created in the same way as in previous studies and results are given.