Investigation of the Carrier Concentration and Laser Peak Intensity on the Terahertz Pulse Generated by Photoconductive Antennas Based On LT-GaAs
Subject Areas : Majlesi Journal of Telecommunication DevicesMohamad Ali Malakoutian 1 , Morteza Fathipour 2
1 - University of Tehran
2 - University of Tehran
Keywords: en,
Abstract :
The possibility of terahertz generation has been investigated from a photoconductive switch based on GaAs, gated by a femtosecond laser. The emission properties of photoconductive antenna (PCA) with low-temperature-grown (LT) GaAs have been studied. In such GaAs materials presence of the charged defects induces a redistribution of the electric field between the antenna electrodes. This effect has a huge influence on the amplitude of the radiated terahertz field. In this work we demonstrate that carrier concentration enhances radiation power. Results obtained as a function of the laser excitation power (with 100 fs rise time and 1KHz repetition rate) and carrier concentration are discussed and a comparison of the performance of these devices with a conventional antenna-type (dipole) emitter is given.
[1] T. Lo er, K.J. Siebertt, N. Hasegawa, T. Hahn, G. Loata, R. Wipf, M. Kress, M. Thomson, and H.G Roskos, “Terahertz surface and interface characterization”, 2005 IEEE MTT-S International Microwave Symposium Digest, pages 4, 2005.
[2] B. Ferguson, S. Wang, D. Gray, D. Abbott, and X-C Zhang, “Towards functional 3d t-ray imaging”, Phys. Med. Biol, 47:3735_3742, 2002.
[3] Anthony J. Fitzgerald, Vincent P. Wallace, Mercedes Jimenez-Linan, Lynda Bobrow, Richard J. Pye, Anand D. Purushotham, and Donald D. Arnone, “Terahertz Pulsed Imaging of Human Breast Tumors”, Radiology, 239(2):533_ 540, 2006.
[4] William R. Tribe, David A. Newnham, Philip F. Taday, and Michael C. Kemp, “Hidden object detection: security applications of terahertz technology”, In R. Jennifer Hwu, editor, Proceedings of SPIE, volume 5354 of Terahertz and Gigahertz Electronics and Photonics III, pages 168_176, 2004.
[5] J. F. Fuller, E. F. Fuchs, and K. J. Roesler, “Influence of harmonics on power distribution system protection,” IEEE Trans. Power Delivery, vol. 3, pp. 549-557, Apr. 1988.
[6] Auston, D.H., Cheung, K.P., and Smith, P.R.: “Picosecond photoconducting hertzian dipoles”, Appl. Phys. Lett., 1984, 45, (3), pp. 284–286
[7] Grischkowsky, D., Keiding, S., Vanexter, M., and Fattinger, “Far-infrared time-domain spectroscopy with terahertz beams of dielectrics and semiconductors”, J. Opt. Soc. Am. B, 1990, 7, (10), pp. 2006–2015
[8] Zhang, X.C., and Auston, “Optoelectronic measurement of semiconductor surfaces and interfaces with femtosecond optics”, J. Appl. Phys., 1992, 71, (1), pp. 326–338
[9] Hu, B.B., Zhang, X.C., Auston, D.H., and Smith, “Free-space radiation from electrooptic crystals”, Appl. Phys. Lett., 1990, 56, (6), pp. 506–508
[10] Roskos, H.G., Nuss, M.C., Shah, J., Leo, K., Miller, D.A.B., Fox, A.M., Schmit-Trink, S., and Kohler, “Coherent submillimeter-wave emission from charge oscillations in a double-well potential”, Phys. Rev. Lett., 1994, 68, (14), pp. 2216–2219
[11] Tani, M., Fukasawa, R., Abe, H., Matsuura, S., Sakai, K., and Nakashima, “Terahertz radiation from coherent phonons excited in semiconductors”, J. Appl. Phys., 1998, 83, (5), pp. 2473–2477.
[12] J. T. Darrow, X.-C. Zhang, D. H. Auston and J. D. Morse: IEEE J. Quantum Electron. 28 (1992) 1607.R.
[13] D. M. Caughey and R. E. Thomas, “Carrier mobilities in silicon empirically related to doping and field,” Proc. IEEE, vol. 55, pp. 2192-2193, 1967.
[14] R. Luebbers, K. Kunz, M. Schneider, and F. Hunsberger, “A finitedifference time-domain near zone to far zone transformation”, IEEE Trans. Antennas. Propagat., vol 39, no 4, pp 429-433, April 1991.