Photonic Band Gap Materials: Light Control at Will




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Significant modification of the spontaneous emission of quantum dots near the surface of a self-assembled three-dimensional photonic crystal



Zheng-Qi Liu, Li-Jun Wu, Sheng Lan

Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, Guangdong 510006, People’s Republic of China


Abstract


In order to investgate the photon localization efficiently, it is really important to fabricate the high quality photonic crystal (PC) [1,2]. By using pressure controlled isothermal heating vertical deposition technique [3] three-dimensional photonic crystal (3D PC) heterostructures with high quality were fabricated [4]. The high quality of the formed heterostructures was reflected in the deeper band gaps and sharper band edges as compared to the heterostructures reported so far. A significant improvement in the quality was achieved by introducing a thin TiO2 buffer layer between the two constitutional PCs. It is revealed that the disorder caused by lattice mismatch was successfully removed upon the use of the buffer layer. As a result, the main features of the band gaps in the constitutional PCs were inherited by the formed heterostructures. The crucial role of the thin buffer layer was also verified by numerical simulations based on finite-difference time-domain technique (FDTD).

Based on the PC, many investigations have been done to the modification of the spontaneous emission since 1978. There are many relative studies on the modification based on the two dimensional PC slabs [5] and also inside of 3D PC [6,7]. But up to now, there is still a bare field to the surface modification of spontaneous emission of a self-assembled 3D PC despite there being an important report on the surface state to the three-dimensional woodpile structure PC [8]. The spontaneous emission of semiconductor quantum dots (QDs) uniformly distributed in a thin polymer film, with a wide range of thickness from 33 nm to 210 nm to different situations, on which 3D PCs was fabricated. These samples are investigated experimentally by time-resolved photoluminescence measurement and numerically by FDTD simulation. It is revealed [9] that the spontaneous emission rate of the QDs can be modified at wavelengths corresponding to the band edges and band gap of the PC. While an obvious increase in the lifetime of the QDs is found at the band gap center, a significant reduction in the lifetime by one order of magnitude is observed at the short-wavelength band edge


Author to whom correspondence should be addressed.

E- mail: slan@scnu.edu.cn.


References

[1] E. Yablonovitch, Phys. Rev. Lett. 58 2059 (1987).

[2] S. John, Phys. Rev. Lett. 58 2486 (1987).

[3] Z. Y. Zheng, X. Z. Liu, Y. H. Luo, B. Y. Cheng, D. Z. Zhang, Q. B. Meng and Y. R. Wang, Appl.Phys. Lett. 90 051910 (2007).

[4] Z. Q. Liu, T. H .Feng, Q. F. Dai, L. J. Wu, S. Lan, Chin.Phys.B 18 2383 (2009).

[5] N. Ganesh, W. Zhang, P. C. Mathias, E. Chow, J. A. N. T. Soares, V. Malyarchuk, A. D. Smith, and B. T. Cunninghan, Nat. Nanotech. 2, 515 (2007).

[6] R. Colombelli, K. Srinivasan, M. Troccoli, O. Painter, C. F. Gmachl, D. M. Tennant, A. M.

Sergent, D. L. Sivco, A. Y. Cho, and F. Capasso, Science 302, 1374 (2003).

[7] S. Strauf. K. Hennessy, M. T. Rakher, Y. S. Choi, A. Badolato, L. C. Andreani, E. L. Hu, P. M. Petroff, and D. Bouwmeester, Phys. Rev. Lett. 96, 127404 (2006).

[8] K. Ishizaki, S. Noda, Nature 460, 367 (2009).

[9] Z. Q. Liu, T. H .Feng, Q. F. Dai, L. J. Wu, S. Lan, C. R. Ding, H. Z. Wang, A. V. Gopal, (unpublished).


Fabrication of three-dimensional multilayer photonic crystal based on Stereolithography and gelcasting and its microwave properties



Sun kun

(State key laboratory of Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 China)


Abstract:


In this paper, we bring forward a new process to fabricate three-dimensional multilayer photonic crystal using Stereolithography (SL) and gelcasting. Resin mold layer was designed and fabricated based on SL technology, slurries loaded with 55vol% Al2O3 powder and 55vol% TiO2 powder respectively were prepared, and using the method of gelcasting, multilayer photonic crystal with diamond structure was fabricated. The photonic crystal shows a band gap around 11.6GHZ, which accords with the simulation result.


Key words: Stereolithography, gelcasting, photonic crystal, three-dimensional


Terahertz subwavelength filter based on a 2D lattice of metal wires



Keyu Tao, Gaoxin Qiu, Guoliang Zheng, Qiang Liu, Ling Li, Zhengbiao Ouyang

THz Technical Research Center of Shenzhen University, Shenzhen 518060, China

Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Shenzhen 518060, China

College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060, China


Abstract


Finite-difference time-domain method is used to investigate the band structures and transmission spectra of a 2D square lattice made of metallic wires. All the results show that the transmission can be affected by factors such as wave polarization, incidence direction, and wire radius. It is found that, the Γ-M direction for TE wave and small radius of metal wires are preferable for a high pass filter, while the Γ-X direction for TM wave and comparatively greater radius of metal wires are suitable for a low pass or a wide stop-band filter. Band edges of the filters can be tuned by adjusting the radius of wires and lattice constant. The key spectral features of the band structure and the corresponding transmission spectrum are strongly correlated. Our work demonstrates that detailed band map can provide more information than effective medium theory for the understanding of transmission properties, which are essential for designing wave filters, even in the subwavelength range.


The method of rapidly manufacturing 3D photonic crystal and performance research*



Minjie WANG1, Dichen LI1, Wei DAI2, Hong WANG2,

Zhiyuan SHEN2, Yawen HU1, Wei ZHANG1

(1State key laboratory of Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, 710049)

(2Electronic Materials Research Laboratory, Key Lab of the Ministry of Education,

Xi’an Jiaotong University, Xi’an, 710049)


Abstract


In this paper, a method used to manufacture rapidly three-dimension photonic crystal has been introduced. With stereolithography and gel casting, three-dimension photonic crystal with diamond structure could be fabricated. The test of microwave frequency spectrum shows that, bandgap of the photonic crystal obtained is between 10.24GHz-12.22GHz and relative bandwidth is 0.176, matching closly with that designed theoretically. The technique combining stereolithography and gel casting provides an efficient method to rapidly manufacture three-dimension photonic crystal based on frequency of milimeter wave and research its particular performance.

Key words: Three-dimension photonic crystal; Stereolithography; Gel casting;


*Supported by Program for Changjiang Scholars and Innovative Research Team in University (IRT0646); Supported by a grant from the Key Programs of National Natural Science Fundation (No. 50835007)


Polarization-independent self-collimation based on pill-void photonic crystals with square symmetry



Yi Xu, Xiao-Jun Chen, Sheng Lan, Qiao-Feng Dai, Qi Guo and Li-Jun Wu*

Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006, P.R. China

*Corresponding author: ljwu@scnu.edu.cn


Abstract:


We investigate discrepancy and similarity in dispersion relations between transverse-electric (TE) and transverse-magnetic (TM) polarizations in rectangular, square and triangular two-dimensional photonic crystals. It is found that the square lattice is the most appropriate candidate to realize polarization-independent, i.e. absolute self-collimation (ASC) in the first photonic band since it possesses not only a relatively broad angular range for self-collimation but also a small difference in dispersion relations between TE and TM modes. By tailoring the shape of air voids in the square-lattice-based structure, the electric-field vector can be rotated to reduce the discrepancy between TE and TM modes whereby the frequency bandwidth of ASC can be enlarged to ~4.8%. The ASC phenomenon is demonstrated by numerical experiments based on a finite-difference time-domain (FDTD) technique with negligible propagation


Modification of two-photon excited fluorescence from quantum dots on photonic crystals



Xingsheng Xu1, 2, Toshiki Yamada2, Hongda Chen1

1 State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China (Email: xsxu@semi.ac.cn)

2 Kobe ICT Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka, Nishi-Ku, Kobe 651-2492, Japan


Abstract


Two-photon excited fluorescence from CdSe quantum dots at an emitting wavelength of 650 nm on SiN photonic crystals (PCs) photonic crystals is investigated. The SiN PC was fabricated by using electron beam lithography and reactive ion etching (Fig.1). The silicon below SiN was wet etched to form a freestanding SiN membrane, and the thickness of the SiN slab was about 160 nm.1 The CdSe quantum dots (QDs, from Invitrogen Corp., ITK amino Qdots) in water solution was dropped onto the surface of SiN PC. The sample was excited by a polarized light from a femtosecond (fs) laser. The recorded spectra of two-photon excited fluorescence (TPF) in the vertical direction at room temperature are shown in Fig.2. The above four lines are the spectra of TPF from CdSe QDs on the surface of SiN PCs with lattice constants of 580 nm, 520nm, 440nm and 380 nm excited by fs laser at wavelength 800 nm, respectively.1 The bottom line is the spectrum of TPF measured from CdSe QDs without PCs on the same condition. Compared with the spectra without PCs, more than 14-fold enhancement was obtained with PC. The mechanism of enhancement was explained by using photonic band structure, and the enhancement was attributed to the coupling to leaky mode of the photonic crystal slab.2 It was also found that all the spectra from PCs shift to blue, and the profile of spectrum and the shifting value are different for PCs with different lattice constants. The mechanisms responsible for the blue shift of TPF in PCs are attributed to the intermixing of the QD and the barrier material.3


Reference

1. X. S. Xu, T. Yamada, S. Yokoyama, Opt. Lett. (in press).

2. M. Boroditsky, T. F. Krauss, et al., Appl. Phys. Lett. 75, 1036(1999).

3. A. Rastelli, et al., Appl. Phys. Lett. 90, 073120(2007).


Control of spontaneous emission of a double-driven four-level atom in photonic crystals



Zhang Bing, Sun Xiudong

Department of Physics, Harbin Institute of Technology, Harbin 150001, China


Abstract


We present the coherent control of spontaneous emission of a double-driven four-level atom embedded in the photonic crystals. The spontaneous emission spectra of the same atomic system in free space is shown to compare with that in photonic crystal with different relative positions of the upper levels from upper band-edge frequency. It is found that spontaneous emission property of the atomic system depends both on the phase of microwave field coupling the two upper levels and on the location of the upper band-edge. As one transition frequency is at the photonic band edge, dark line appears in spectra due to destructive interference effect though the spontaneous emission is partly depressed. Furthermore, quantum interference property between the decay channels depends strongly on the phase of microwave field, with increase of the phase, the dark line disappears. A physical understanding of these results is obtained by invoking the dressed atom approach.

Keywords: Spontaneous emission, Photonic crystal
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