Terahertz radiation of a butterfly-shaped photoconductive antenna(invited)
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摘要
The terahertz(THz) far-field radiation properties of a butterfly-shaped photoconductive antenna(PCA) were experimentally studied using a home-built THz time-domain spectroscopy(THz-TDS) setup.To distinguish the contribution of in-gap photocurrent and antenna structure to far-field radiation,polarization-dependent THz field was measured and quantified as the illuminating laser beam moved along the bias field within the gap region of electrodes. The result suggests that, although the far-field THz radiation originates from the in-gap photocurrent, the antenna structure of butterfly-shaped PCA dominates the overall THz radiation. In addition, to explore the impact of photoconductive material,radiation properties of butterfly-shaped PCAs fabricated on both low-temperature-grown GaAs(LT-GaAs) and semi-insulating GaAs(Si-GaAs) were characterized and compared. Consistent with previous experiments, it is observed that while Si-GaAs-based PCA can emit higher THz field than LT-GaAs-based PCA at low laser power, it would saturate more severely as laser power increased and eventually be surpassed by LT-GaAs-based PCA. Beyond that, it is found the severe saturation effect of Si-GaAs was due to the longer carrier lifetime and higher carrier mobility, which was confirmed by the numerical simulation.
The terahertz(THz) far-field radiation properties of a butterfly-shaped photoconductive antenna(PCA) were experimentally studied using a home-built THz time-domain spectroscopy(THz-TDS) setup.To distinguish the contribution of in-gap photocurrent and antenna structure to far-field radiation,polarization-dependent THz field was measured and quantified as the illuminating laser beam moved along the bias field within the gap region of electrodes. The result suggests that, although the far-field THz radiation originates from the in-gap photocurrent, the antenna structure of butterfly-shaped PCA dominates the overall THz radiation. In addition, to explore the impact of photoconductive material,radiation properties of butterfly-shaped PCAs fabricated on both low-temperature-grown GaAs(LT-GaAs) and semi-insulating GaAs(Si-GaAs) were characterized and compared. Consistent with previous experiments, it is observed that while Si-GaAs-based PCA can emit higher THz field than LT-GaAs-based PCA at low laser power, it would saturate more severely as laser power increased and eventually be surpassed by LT-GaAs-based PCA. Beyond that, it is found the severe saturation effect of Si-GaAs was due to the longer carrier lifetime and higher carrier mobility, which was confirmed by the numerical simulation.
The terahertz(THz) far-field radiation properties of a butterfly-shaped photoconductive antenna(PCA) were experimentally studied using a home-built THz time-domain spectroscopy(THz-TDS) setup.To distinguish the contribution of in-gap photocurrent and antenna structure to far-field radiation,polarization-dependent THz field was measured and quantified as the illuminating laser beam moved along the bias field within the gap region of electrodes. The result suggests that, although the far-field THz radiation originates from the in-gap photocurrent, the antenna structure of butterfly-shaped PCA dominates the overall THz radiation. In addition, to explore the impact of photoconductive material,radiation properties of butterfly-shaped PCAs fabricated on both low-temperature-grown GaAs(LT-GaAs) and semi-insulating GaAs(Si-GaAs) were characterized and compared. Consistent with previous experiments, it is observed that while Si-GaAs-based PCA can emit higher THz field than LT-GaAs-based PCA at low laser power, it would saturate more severely as laser power increased and eventually be surpassed by LT-GaAs-based PCA. Beyond that, it is found the severe saturation effect of Si-GaAs was due to the longer carrier lifetime and higher carrier mobility, which was confirmed by the numerical simulation.
引文
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[14]Zhang J,Tuo M,Liang M,et al.Contribution assessment of antenna structure and in-gap photocurrent in terahertz radiation of photoconductive antenna[J].J App Phys,2018,124:053107.
[15]Darrow J T,Zhang X C,Auston D H,et al.Saturation properties of large-aperture photoconducting antennas[J].IEEE Journal of Quantum Electronics,1992,28(6):1607-1616.
[16]Keil U D,Dykaar D R.Ultrafast pulse generation in photoconductive switches[J].IEEE Journal of Quantum Electronics,1996,32(9):1664-1671.
[17]Benicewicz P K,Taylor A J.Scaling of terahertz radiation from large-aperture biased InP photoconductors[J].Optics Letters,1993,18(16):1332-1334.
[18]Sano E,Shibata T.Fullwave analysis of picosecond photoconductive switches[J].IEEE Journal of Quantum Electronics,1990,26(2):372-377.
[19]Moreno E,Pantoja M F,Garcia S G,et al.Timedomain numerical modeling of THz photoconductive antennas[J].IEEE Transactions on Terahertz Science and Technology,2014,4(4):490-500.
[20]Zhang J,Tuo M,Liang M,et al.Numerical analysis of terahertz generation characteristics of photoconductive antenna[C]//IEEE Antennas and Propagation Society International Symposium(APSURSI),2014:1746-1747.
[21]Zhang J.Numerical analysis of the emission properties of terahertz photoconductive antenna by finitedifference-time-domain method[J].arXiv Preprint arXiv,2014,1407.2881:1-11.
[2]Jepsen P U,Cooke D G,Koch M.Terahertz spectroscopy and imaging-Modern techniques and applications[J].Laser&Photonics Reviews,2011,5(1):124-166.
[3] Burford N M,El-Shenawee M O.Review of terahertz photoconductive antenna technology[J].Optical Engineering,2017,56(1):010901.
[4]Tani M,Matsuura S,Sakai K,et al.Emission characteristics of photoconductive antennas based on low-temperature-grown GaAs and semi-insulating GaAs[J].Applied Optics,1997,36(30):7853-7859.
[5]Jepsen P U,Jacobsen R H,Keiding S R.Generation and detection of terahertz pulses from biased semiconductor antennas[J].Journal of the Optical Society of America B,1996,13(11):2424-2436.
[6]Tani M,Yamamoto K,Estacio E S,et al.Photoconductive emission and detection of terahertz pulsed radiation using semiconductors and semiconductor devices[J].Journal of Infrared,Millimeter,and Terahertz Waves,2012,33(4):393-404.
[7]Hou L,Shi W.An LT-GaAs terahertz photoconductive antenna with high emission power,low noise,and good stability[J].IEEE Transactions on Electron Devices,2013,60(5):1619-1624.
[8]Reklaitis A.Comparison of efficiencies of GaAs-based pulsed terahertz emitters[J].Journal of Applied Physics,2007,101:116104.
[9]Miyamaru F,Saito Y,Yamamoto K,et al.Dependence of emission of terahertz radiation on geometrical parameters of dipole photoconductive antennas[J].Applied Physics Letters,2010,96(21):211104.
[10]Gao Y,Yang C E,Chang Y,et al.Terahertz-radiationenhanced broadband terahertz generation from large aperture photoconductive antenna[J].Applied Physics B,2012,109(1):133-136.
[11]Liu T A,Chou R H,Pan C L.Dependence of terahertz radiation on gap sizes of biased multi-energy arsenicion-implanted and semi-insulating GaAs antennas[J].Applied Physics B,2010,95(4):739-744.
[12]Kono S,Gu P,Tani M,et al.Temperature dependence of terahertz radiation from n-type InSb and n-type InAs surfaces[J].Applied Physics B,2000,71(6):901-904.
[13]Zhang J,Mikulics M,Adam R,et al.Generation of THz transients by photoexcited single-crystal GaAs mesostructures[J].Applied Physics B,2013,113(3):339-344.
[14]Zhang J,Tuo M,Liang M,et al.Contribution assessment of antenna structure and in-gap photocurrent in terahertz radiation of photoconductive antenna[J].J App Phys,2018,124:053107.
[15]Darrow J T,Zhang X C,Auston D H,et al.Saturation properties of large-aperture photoconducting antennas[J].IEEE Journal of Quantum Electronics,1992,28(6):1607-1616.
[16]Keil U D,Dykaar D R.Ultrafast pulse generation in photoconductive switches[J].IEEE Journal of Quantum Electronics,1996,32(9):1664-1671.
[17]Benicewicz P K,Taylor A J.Scaling of terahertz radiation from large-aperture biased InP photoconductors[J].Optics Letters,1993,18(16):1332-1334.
[18]Sano E,Shibata T.Fullwave analysis of picosecond photoconductive switches[J].IEEE Journal of Quantum Electronics,1990,26(2):372-377.
[19]Moreno E,Pantoja M F,Garcia S G,et al.Timedomain numerical modeling of THz photoconductive antennas[J].IEEE Transactions on Terahertz Science and Technology,2014,4(4):490-500.
[20]Zhang J,Tuo M,Liang M,et al.Numerical analysis of terahertz generation characteristics of photoconductive antenna[C]//IEEE Antennas and Propagation Society International Symposium(APSURSI),2014:1746-1747.
[21]Zhang J.Numerical analysis of the emission properties of terahertz photoconductive antenna by finitedifference-time-domain method[J].arXiv Preprint arXiv,2014,1407.2881:1-11.