在本論文的研究中我們展示了兩個新穎的光電發射器，一個是利用低溫成長砷化鎵(LTG-GaAs)為基材的分離式傳輸複合光二極體(STR-PD) ，另一者是以砷化鎵/砷化鋁鎵(GaAs/AlGaAs)為基材的單載子傳輸光二極體(UTC-PD)。此兩種元件結合槽孔式的單極圓碟微波天線，其具有無需要整合在Si-lens的優點。藉由中心波長為800nm超快速飛秒光脈衝光訊號的激發下，我們的光電發射器可幅射出一個強而有力的次兆赫波脈衝訊號(最大功率20mW)和一個較寬的頻帶(100GHz到250GHz)。並由兆赫波時域光譜(TDS)系統量測並轉換成頻域訊號，此頻域訊號可應用在兆赫波資料連結系統內。而當元件操作在逆偏下，此光電發射器的峰值功率（峰值電場平方）隨著外加偏壓有顯著的變化，並經由訊號歸一化分析後，我們可以清楚的看到峰值功率與外加逆偏壓呈現一線性關係，此線性現象對於我們調制光次兆赫波的傳輸資料，有很大的益助。

In this paper, we demonstrated two novel photonic transmitters; one is composed of low-temperature-grown GaAs (LTG-GaAs) based separated-transport-recombination photodiode (STR-PD) and the other is GaAs/AlGaAs based Uni-traveling-carrier photodiode (UTC-PD). Both devices are integrated with broadband micromachined monopole antennas but without the integration with Si-lens. Under femto-second optical pulse illumination which the wavelength of around 800nm, the photonic-transmitter can radiate strong sub-THz pulses (20mW peak-power) with a wide bandwidth (100~250GHz). Such result was directly measured by a THz-TDS system, which could be used as a THz UWB data link system. The bias dependent high-peak-power performance of our device implies its application of photonic emitter and data modulator in photonic sub-THz UWB system.

[1] M. Z. Win and R. A. Scholtz, “ Impulse Radio: How it works,” IEEE Commun. Lett., vol. 2, pp. 36-38, 1998.
[2] K. Humphreys, J.P. Loughran, M. Gradziel, W. Lanigan, T. Ward, J. A. Murphy, C. O''Sullivan, “Medical applications of terahertz imaging: a review of current technology and potential applications in biomedical engineering,” Proc. EMBC, vol. 1, pp. 1302 - 1305, 2004.
[3] K. Kato, “Ultrawide-Band/High-Frequency Photodetectors,” IEEE Trans. Microwave Theory Tech., vol. 47, pp. 1265-1281, Jul., 1999.
[4] J. R. Pardo, J. Cernicharo, E. Serabyn, “Atmospheric transmission at microwaves (ATM): an improved model for millimeter/submillimeter applications,” IEEE Trans. on Antennas and Propagation, vol. 49, no. 12, pp. 1683 – 1694, Dec. 2001.
[5] M. C. Gaidis, H. M. Pickett, C. D. Smith, S. C. Martin, R. P. Smith, P. H. Siegel, “A 2.5-THz receiver front end for spaceborne applications,” IEEE Trans. on Microwave Theory and Tech., vol.48, no. 4, pp. 733 – 739, Apr., 2000.
[6] H. Eisele, A. Rydberg, and G. I. Haddad, “Recent advances in the performance of InP Gunn devices and GaAs TUNNET diodes for the 100-300GHz frequency range and above,” IEEE Trans. Microwave Theory Tech., vol. 48, pp. 626-631, Apr., 2000.
[7] Y. P. Gousev, I. V. Altukhov, K. A. Korolev, V. P. Sinis, M. S. Kagan, E. E. Haller, M. A. Odnoblyudov, I. N. Yassievich, and K.-A. Chao, “Widely tunable continuous-wave THz laser,” Appl. Phys. Lett., vol. 75, pp. 757-759, Aug., 1999.
[8] N. Orihashi, S. Suzuki, and M. Asada, “One THz harmonic oscillation of resonant tunneling diodes, ” Appl. Phys. Lett., vol. 87, pp. 233501, 2005.
[9] M. J. W. Rodwell, S. T. Allen, R. Y. Yu, M. G. Case, U. Bhattacharya, M. Reddy, E. Carman, M. Kamegawa, Y. Konishi, J. Pusl, R. Pullela, “Active and nonlinear wave propagation devices in ultrafast electronics and optoelectronics [and prolog]” Proceedings of the IEEE, vol. 82, pp. 1037-1059, Jul., 1994.
[10] H. Ito, T. Furuta, F. Nakajima, K. Yoshino, T. Ishibashi, “Photonic Generation of Continuous THz Wave Using Uni-Traveling-Carrier Photodiode,” J. of Lightwave Technol., vol. 23, pp. 4016-4021, Dec., 2005.
[11] Kirk Steven Giboney, Ph. D. Thesis, University of California at Santa Barbara, 1995.
[12] Yi-Jen Chiu, Ph. D. Thesis, University of California at Santa Barbara, 1999.
[13] 許晉瑋，金屬-半導體-金屬 行波式光偵測器，國立臺灣大學/光電工程學研究所博士論文(2001)
[14] Y. -L. Huang, and C. -K. Sun, “Nonlinear saturation behaviors of high-speed p-i-n photodetectors,” J. of Lightwave Technol., vol. 18, pp. 203-212, Feb., 2000.
[15] K. J. Williams, R. D. Esman, and M. Degenais, “Nonlinearities in p-i-n Microwave Photodetectors,” J. of Lightwave Technol., vol. 14, pp. 84-96, Jan., 1996.
[16] S. Gupta, J. F. Whitaker, and G. A. Mourou, “Ultrafast Carrier Dynamics in III-V Semiconductors Grown by Molecular-Beam Epitaxy at Very Low Substrate Temperatures,” IEEE J. of Quantum Electronics, vol. 28, pp. 2464-2472, 1992.
[17] J. P. Ibbetson, Ph. D. Thesis, University of California at Santa Barbara, 1998.
[18] J. -W. Shi, Y. -H. Chen, K. G. Gan, Y. J. Chiu, John. E. Bowers, M. -C. Tien, T.-M. Liu, and C. -K. Sun, “Nonlinear Behaviors of Low-Temperature-Grown GaAs-Based Photodetectors Around 1.3-μm Telecommunication Wavelength,” IEEE Photon. Tech. Lett., vol. 16, pp. 242-244, Jan., 2004.
[19] C. -K. Sun, Y. -H. Chen, J. -W. Shi, Y. -J. Chiu, K. G. Gan, and J. E. Bowers, “Electron relaxation and transport dynamics in low-temperature-grown GaAs under 1eV optical excitation,” Appl. Phys. Lett., vol. 83, pp. 911-913, Aug., 2003.
[20] H. Ito, S. Kodama, Y. Muramoto, T. Furuta, T. Nagatsuma, T. Ishibashi, “High-Speed and High-Output InP–InGaAs Uni-traveling Carrier Photodiodes,” IEEE J. of Sel. Topics in Quantum Electronics. vol. 10, pp. 709-727, Jul./Aug., 2004.
[21] M. Levinshtein, S. Rumyantsev, and M. Shur, Handbook Series on Semiconductor Parameters, World Scientific, Singapore, p. 2., 1996.
[22] N. Li, X. Li, S. Demiguel, X. Zheng, J. C. Campbell, D. A. Tulchinsky, K. J. Williams, T. D. Isshiki, G. S. Kinsey, and R. Sudharsansan, “High-saturation-current charge-compensated InGaAs-InP uni-traveling-carrier photodiode” IEEE Photon. Tech. Lett., vol. 16, pp. 864-866, 2004.
[23] Y. -C. Liang, and N. -W. Chen, “An ultra-broadband coplanar waveguide-fed circular monopole antenna,” EuCAP 2007, Edinburgh, UK, Nov., 2007.
[24] W. L. Stutzman and G. A. Thiele, Antenna theory and design, Chapter 6, 2nd Ed., John Wiely and Sons, 1998.
[25] 莊達人, “VLSI製造技術”, 高立圖書公司, 1995.
[26] T. -A. Liu, G. -R. Lin, Y. -C. Chang, C. -L. Pan, “Wireless audio and burst communication link with directly modulated THz photoconductive antenna,” Optic. Express, vol. 13, Issue 25, pp. 10416-10423, Dec., 2005.
[27] Y. -T. Li, J. -W. Shi, C. -L. Pan, C. -H. Chiu, W. -S. Liu, N. -W. Chen, C. -K. Sun, and J. -I. Chyi, “Sub-THz Photonic Transmitters Based on Separated-Transport-Recombination Photodiodes and a Micromachined Slot Antenna,” IEEE Photon. Tech. Lett., vol. 19, pp. 840-842, Jun., 2007.
[28] M. Tani, S. Matsuura, K. Sakai, and S. Nakashima, “Emission characteristics of photoconductive antennas based on low-temperature-grown GaAs and semi-insulating GaAs,” Applied Optics, vol. 36, pp. 7853-7859, Oct., 1997.
[29] N. Shimizu, N. Watanabe, T. Furuta, and T. Ishibashi, “InP-InGaAs Uni-Traveling-Carrier Photodiode With Improved 3-dB Bandwidth of Over 150GHz,” IEEE Photon. Tech. Lett., vol. 10, pp. 412-414, Mar., 1998.
[30] A. Hirata, T. Furuta, H. Ito, and T. Nagatsuma, “10-Gb/s Millimeter-Wave Signal Generation Using Photodiode Bias Modulation,” J. of Lightwave Technol., vol. 24, pp. 1725-1731, Apr., 2006.
[31] R. Xu, Y. Jin, and C. Nguyen, “Power-Efficient Switching-Based CMOS UWB Transmitters for UWB Communications and Radar Systems,” IEEE Trans. Microwave Theory Tech., vol. 54, pp. 3271-3277, Aug., 2006.
[32] S. Ramsey, E. Funk, and C. H. Lee, “A wireless photoconductive receiver using impulse modulation and direct sequence code division,” Int. Topical Meeting Microwave Photon., vol. 1, pp. 265-268, 1999.
[33] H. Togo, P. -C. P. Sah, N. Shimizu, T. Nagatsuma, “Gigabit Impulse Radio Link Using Photonic Signal-Generation Techniques,” European Microwave Conference 2005, vol. 1, pp. 4-7, Oct., 2005.
[34] T. -A. Liu, G. -R. Lin, Y. -C. Chang, C. -L. Pan, “Wireless audio and burst communication link with directly modulated THz photoconductive antenna,” Optic. Express, vol. 13, Issue 25, pp. 10416-10423, Dec., 2005.
[35] S. M. Duffy, S. Verghese, K. A. McIntosh, A. Jackson, A. C. Gossard, and S. Matsuura, “Accurate modeling of dual dipole and slot elements used with photomixers for coherent terahertz output power,” IEEE Trans. Microwave Theory Tech., vol. 49, pp. 1032-1038, Jun., 2001.
[36] J. -W. Shi, Y. -T. Li, C. -L. Pan, M. L. Lin, Y. S. Wu, W. S. Liu, and J. -I. Chyi, “Bandwidth enhancement phenomenon of a high-speed GaAs-AlGaAs based unitraveling carrier photodiode with an optimally designed absorption layer at an 830nm wavelength,” Appl. Phys. Lett., vol. 89, pp. 053512, 2006.
[37]K. P. Yang﹐P. L. Richaeds﹐and Y. R. Shen, “Generation of Far-Infrared Radiation by Picosecond Light Pulses in LiNbO3,” Appl. Phys. Lett., vol. 19, pp 320-323, 1971.