September 2009 - November 2009
Publisher: Chairman Sheng-Lung Huang  Editors: Prof. Jui-che Tsai, Ms. Hsiao-wen Lin  January 15, 2010

Congratulations! Dr. Tingye Li, Distinguished Chair Professor of GIPO and Academician of Academia Sinica, receives the IEEE top honor gold medal.

The Institute of Electrical and Electronic Engineers (IEEE) awarded its top honor gold medal to our Distinguished Chair Professor, Academician Tingye Li, honoring him for his extraordinary contributions to fiber-optic communication technology. Congratulations on this great achievement!

Congratulations! GIPO Professor Hung-Chun Chang receives the title of “2010 OSA Fellow”.

Congratulations! GIPO Professor Ching-Fuh Lin receives the 2009 Outstanding Electrical Engineering Professor Award from the Chinese Institute of Electrical Engineering.


August “Photonics Forum” Lecture Highlights


August 26th (Wednesday), 2009 10:30 AM
Speaker: Prof. Roel Baets (Department of Information Technology, Ghent University)
Topic: Silicon Photonics: Opportunities and Challenges

Professor Roel Baets visited GIPO on August 26th (Wednesday), 2009, and lectured in Auditorium 105, EE Building 2. The lecture, “Silicon Photonics: Opportunities and Challenges” was attended with enthusiasm by GIPO professors and students, and everyone learned much from the lecture.


October “Photonics Forum” Lecture Highlights


October 23rd (Friday), 2009 2:30 PM
Speaker: Prof. Ray-Kuang Lee (Institute of Photonics Technologies, National Tsing Hua University)
Topic: Light localization in classical and quantum worlds

Professor Ray-Kuang Lee visited GIPO on October 23rd (Friday), 2009, and spoke in Room 113, Barry Lam Hall. His lecture, “Light localization in classical and quantum worlds” was attended with enthusiasm by GIPO professors and students, and everyone learned a lot.

Vice Chairman Gong-Ru Lin (right), the host, and Professor R. K. Lee (left)


October 30th (Friday), 2009 2:30 PM

Speaker: Prof. Chii-Chang Chen (Department of Optics and Photonics, National Central University)
Topic: My France Dream - my experiences in French life, culture, and study

Professor Chi-Chang Chen visited GIPO on October 30th (Friday), 2009, and spoke about his France dream, his experiences in French life, culture, and study, at room 113, Barry Lam Hall. Chii-Chang Chen is a professor of the Department of Optics and Photonics, National Central University. In his youth, he gave up his original plan of studying in the U.S., and went to France instead to pursue further study. Living in a non English-speaking country for 5 years, the experience of life and the culture shock have greatly augmented his physical and spiritual strength. He believes that if one has a dream and pursues this dream earnestly, one is successful regardless of whether the goal of the dream has been achieved. GIPO students and teachers attended the speech with enthusiasm, and have benefited greatly.

Vice Chairman Gong-Ru Lin (right), the host, and Professor Chii-Chang Chen (left)


~ Series Report of the 1st Microstructure Photography Contest 2009 ~

 (Date of judging: August 17th, 2009; location: B1, Barry Art Gallery, Barry Lam Hall, NTU)

29 photos went into the finals of GIPO’s 1st Microstructure Photography Contest. They were exhibited at the Barry Art Gallery of Barry Lam Hall B1 for the finals on August 17. The photographers were invited to explain and discuss their work at the showing. Afterwards, the judges convened and, after a series of fervent discussion and appraisals, announced the results. All winning photos were displayed at the gallery, and published in succession in the GIPO newsletter. This way, those who were unable to visit the exhibition can still appreciate the brilliance of these photos. 


【Title】Summer Snow
Yi-Hao Pai, Chih-Hsien Cheng, and Chung-Lun Wu


【Title】Man's World
【Photographer】Po-Chun Yeh


【Title】Flame of Flowers
【Photographer】Chieh-Wei Huang


【Title】It Seems that a Nanometer Granule has a Life of Its Own
Ting-Ta Chi


【Title】 A Grain of Sand, A World
【Photographer】Szu-Yu Chen


【Title】Luxuriant Branches and Leaves
【Photographer】Shu-Ting Kuo



~2009 Academic Year GIPO Students' Association Mid-Autumn Festival Party ~

 (Time: September 25th, 2009; Location: 3F Courtyard, Ming Da Hall, EECS NTU)

Composed by: Hsiang-Chun Wei, President of GIPO Students' Association

We are thrilled at the success of this year's Mid-Autumn Festival party. Did you all have a good time eating, chatting and receiving prizes? Thank you all for your participation, which has made this event more wonderful. And, we thank you for your forbearance if there were any flaws or problems we overlooked.

To begin with, I would like to explain our efforts in preparing this event. I believe everyone has noticed that we went the extra mile with decoration this year. Visually we had 3 pairs of large-scale spring festival scrolls written with large soft pens, the main sign with 7 painted moons, lanterns at the entrance, and couplets written by professionals using a writing brush. For your listening enjoyment, we had special Taiwanese background music which, we believe, greatly enhanced the atmosphere of Mid-Autumn Festival. In advertising, we had beautiful posters, specially-designed meal tickets, and special drink tickets. In order to avoid “only early birds getting the worm”, we prepared a Pizza Hut's individual pizza for everyone. There was also a limited amount of special drinks (which allowed us to discover quite a few alcoholics), and a buffet. We prepared so much food that we were able to fill everyone's stomach.

Stage decoration

Delicious food and a flood of revelers

When it was time for the climactic lottery, everyone was given a moon cake for the occasion, which was purchased from Yu Jen Handicapped Training Center. So, each time you take a bite of this moon cake, you know you have done something good. Regarding lottery prizes, we had 50 customized, bracelet flash drives printed with "GIPO" which, we believe, are memorable, and classy souvenirs. We would like to give our special thanks to Chairman Jenn-Gwo Hwu, Department of Electrical Engineering, for his kind donation of valuable Sogo gift certificates for our prizes. As we wanted to have prizes available for almost everyone, our prizes may not have been as valuable as those of the years past. A special point of interest is that, for the first 3 prizes, we also presented pomelos bearing professors' signatures and enlarged “Usavich Diplomas.

Time for the Mid-Autumn Party lottery

In addition, the winners of GIPO's 2009 1st Microstructure Photography Contest were awarded during the party. Since every winner tried the best to shoot his/her award-winning photo, we wanted to take this opportunity to introduce them to you all.

Awarding ceremony of the 1st Microstructure Photography Contest

Awarding ceremony of the 1st Microstructure Photography Contest

We would like to thank the Chairman of GIPO, the Vice Chairman and all the professors for their participation. Also, thank you to Professor Jenn-Gwo Hwu, Chairman of the Department of Electrical Engineering, for his participation and gift certificates. Their assistance has made this party complete and more successful. Thanks to the staff of GIPO and offices of EE Building 2, Barry Lam Hall, and Ming Da Hall for their support and assistance. Lastly, we would like to thank our working staff, Chia-Nying Hu, Yi-Wen Wang, Je-Yu Chang, Jay-Zway Hong, Yen-Liang Liu, Yun-Chi Lee, Yu-Ting Hong, Po-Yu Lin, Shu-Han Hsu, and Hsiao-Yuh Wang, for their hard work in making this event possible. Also, to those special friends who contributed help without receiving prior notice from us, thank you. 

The main sign with seven painted moons

Spring festival scrolls written with large soft pens

Specially-ordered bracelet flash drive
A specially-made first prize: Usavich Diploma
Party organizers




~ 2009 Academic Exchange with Nanjing University Ph.D. Students ~

Time: July 5th ~ 11th, 2009

Location: Nanjing University


Composed by Tzu-Huan Cheng, GIPO Ph.D. candidate (Deputy Team Leader of NTU representative student team)

The time for visiting Nanjing University drew closer and closer with each of the several preparatory meetings we held. I was made a bit nervous by the warnings we had received in our meetings, such as to avoid mentioning politically sensitive topics, to understand Nanjing University's research facilities or related geographical and historical background, etc. Upon arriving in Nanjing and passing through customs, we received a warm welcome from Nanjing University’s representatives, and after the next 6 days of interaction and exchange, we realized that they are in fact very friendly.

During the few days of the seminar, I was deeply moved and inspired by both the professors' lectures and the students' research reports. From the amazing lectures of Professor C. C. Yang, former Chairman of GIPO, Professor Min Xiao, Nanjing University, and Professor and Academician Jianquan Yao, Tianjin University, we learned a lot about the many applications of near-field optics to light-emitting devices, the optical characteristics of nanocrystalline silicon and microstructure, and the development of THz technology and its application to communication. We were especially moved by the elderly Academician Jianquan Yao. Even though he looked tired after having just flown to Nanjing, his determination to educate us was not a bit affected. The professor gave us a lecture without a moment's rest, with enthusiastic participation from the attending students. Although their fields of study may differ a bit, each student’s determination to pursue knowledge is apparent and the same. Such a positive attitude towards research is truly worth studying.

Students from NTU, Nanjing University, and other Mainland Chinese universities then presented their papers, and some of them also presided at the sessions. Through presiding, we gained and practiced the skills of controlling session times, meeting contingencies, and developing proper conference etiquette. There were 4 major topics in this seminar: 1. nonlinear optics and laser technology, 2. nanophotonics and artificial band gap material, 3. wide band gap semiconductor materials and their microstructure, and 4. new optical effects of microstructure materials. Oral reports were all made in mandarin. Thus, aside from some translative technological terms, listeners had basically no problem understanding each speaker. Among these topics, the ones discussing wide band gap semiconductor materials and the new optical effects of microstructure materials incited the most enthusiastic discussions. In these two topics, papers covering microstructure process (nanowire, photonic crystal, nanoparticle and quantum well), material characteristics (silicon nanowire, gallium nitride nanowire, ZnO nanoparticle, aluminium nitride, and aluminium gallium nitride) and simulations (the energy band structure calculations and optical characteristics of the nano materials, negative refraction of materials, the band-gap changes and reflection characteristics of photonic crystals), were presented. With fervent discussions, everyone learned a lot. Among them, I was most impressed by the simulations discussion. Most students could in fact write their own simulation programs, instead of relying on commercial software packages. They were also able to discuss and explain their simulation program writing skills. These indicate that they already had thorough knowledge of the physical phenomena of the device materials. In the discussion, Chuan Zhang, a Nanjing University student, presented an important concept which asserted that, in predicting material characteristics based on physical models, every theory has to be verified by experiments before it could possibly be concluded. Whenever a discrepancy is detected, further verification is needed. Many discoveries were found from such further verification. Lots of great discoveries had actually been observed before they were really noticed; some researchers may have missed receiving the Nobel Prize because of their neglect of some minor discrepancies.

Finally, I would like to discuss my thoughts about this academic exchange. I believe this kind of activity is very valuable, because it not only broadens our fields of vision and provides us with access to different points of view, but also diversifies our own viewpoints and prevents us from confining ourselves to our own domain. The application value of our research would certainly increase greatly if we bring knowledge of other domains into ours. Seeing the rapid growth of Nanjing has greatly changed our limited impression of the city. We need to strive harder to increase our abilities and value and let foreign friends have more opportunities to get to know us. This way, we are visiting foreign countries, and in addition, creating opportunities for foreigners to visit us as well. I hope such activities can continue, and even expand to a larger scale, so that future GIPO students can have such seminars and such opportunities for academic and cultural growth as we do today.



Miniature optical autofocus camera by micromachined fluoropolymer deformable mirror

Professor Guo-Dung Su

Graduate Institute of Photonics and Optoelectronics, National Taiwan University

Along with the progress of image sensors in recent years, fix-focus cameras on mobile electronic devices do not fulfill consumer needs. With the size of mobile devices getting smaller and smaller, the displacement-to-thickness ratio is getting larger, and that makes mechanical motor systems difficult to be packaged inside cameras to achieve autofocus function.

We propose a design using micromachined fluoropolymer deformable mirrors rather than traditional mechanical motor. With low color dispersion and adjustable power range of 20-diopter, deformable mirrors can be integrated into optical module and are well suitable for miniature optical auto-focus camera. A polymer membrane works as a reflective mirror surface to focus the light variably by adjusting the voltage difference. Fig. 1 shows a schematic drawing and photograph of the fabricated device.

We conducted an experiment between optical power versus applied voltage. The polymer membrane was actuated by the electrostatic force and deformation of the polymer membrane can be adjusted by changing voltage difference continuously. The optical power and deformation versus the applied voltage is plotted in Fig. 2. The maximum optical power achieved is around 20-diopter when 160 volts is applied, corresponding to 27-μm deformation at the center of the membrane. The optical power of an organic deformable mirror could be adjusted continuously.

At the beginning, when the mirror was not actuated, the far object (the train) with “HARIBO” can be seen clearly while the near object, the name card with “Jen-Liang Wang”, is blurred as show in Fig. 3(a).  After applying voltage to the deformable mirror, the effective focal length of the system changes. The focal point moves forward so that the near object can be clearly seen. We can see that there are still some aberrations at the edge of the images. This can be fixed by custom-designing the lenses.  We demonstrate that the deformable mirror is feasible as vari-focus devices in camera lens module without moving component. This part is also shown in the video file submitted.

Fig. 1. (a) A schematic drawing of organic deformable mirror and (b) a photograph of the device.

Fig. 2.  Optical power versus applied voltage.

Fig. 3. (a) Image for system without actuating deformable mirror, and (b) image when performing auto-focusing, the mirror is actuated.


White Organic Light-Emitting Devices with Low Driving Voltage and High Efficiency

Professor Jiun-Haw Lee

Graduate Institute of Photonics and Optoelectronics, National Taiwan University

By selectively doping yellow emitter in the ambipolar blue emitting layer (EML), white light organic light-emitting device (OLED) could be obtained and the driving voltage was reduced due to the recombination current increase. We doped rubrene near the maximum recombination zone of our OLED, 4,4'-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl doped in 9,10-bis(2’-naphthyl) anthracene (DPAVBi:ADN), 2V reduction in driving voltage was achieved. Although electron and hole mobilities of ADN are comparable, we found the recombination zone is near the interface of hole-transport layer (HTL) and EML interface the injection barrier for the hole is higher than that for the electron.


Characterizations of GaN-Based LEDs Encompassed with Self-Aligned Nanorod Arrays of Various Distribution Densities

Professor Jian-Jang Huang

Graduate Institute of Photonics and Optoelectronics, National Taiwan University

GaN-based LEDs encompassed with self-aligned nanorod arrays of three types of nanorod arrangement were fabricated by simply using spin-casting and dry etching.  Light diffraction behaviors are characterized by considering the radiation profiles of these structures.  The output power enhancement factor of the S-nanorod device over the conventional one is 27.25% in the vertical direction and 30.43% for the integrated intensity.  This enhancement is omni-directional because the less regular arrangement of S-nanorod structure results in a varying G and omni-directional distribution of radiation modes.  On the other hand, from the radiation profile, the D-nanorod device shows better directionality due to its relatively well-aligned nanorod arrays (and thus less varying lattice vector G) but with a less optical output enhancement.  The relatively well-arranged D-nanorods, especially in the first several columns facing p-mesa act as gratings with groove in the vertical direction and diffract laterally propagated light back toward the p-mesa, thus decreasing the amount of power enhancement.  Also, the existence of higher order diffraction modes enables the S-nanorod device to have a higher power enhancement factor.

Fig. 1. Illustration of the LED device encompassed with nanorod reflectors

Fig. 2. SEM photos of the self-aligned nanorod arrays of the (a) S-nanorod, (b) M-nanorod, and (c) D-nanorod LEDs.  The fill factors are 0.188, 0.285 and 0.467 for (a), (b), and (c), respectively.  (d) Illustration of the triangular lattice for the calculation of the effective lattice constant a for a specific fill factor.

Fig. 3. Measured radiation profiles (a) and the normalized results to the vertical direction (90˚) (b) of the devices under comparison.


Analysis of Highly Conducting Lamellar Gratings with Multidomain Pseudospectral Method

Professor Yih-Peng Chiou’s group

Graduate Institute of Photonics & Optoelectronics, National Taiwan University

Numerical modeling for grating structures plays an important role in their investigation and applications. The performance of the modeling is even essential, when grating periods become comparable to the wavelength and structures are involved with highly conducting materials. The rigorous coupled wave analysis (RCWA) is the most widely used spectral methods. But in recent years, numerical instability problem with TM polarization was discovered when the real part of the refractive index is very small (highly conducting gratings). Another common modal method is the classical modal method which is very powerful technique to approach this problem, but its complicate process to limit the further applications. Here we combine the features of these two numerical methods: the easily solved eigen equation in the grating of RCWA and the analytical mode profiles of modal method. The multidomain pseudospectral frequency method we adopted avoids classical modal methods from finding the roots of dispersion relation especially while complex roots are involved and avoids Runge phenomenon and Gibbs phenomenon to achieve uniform accuracy at the same time. The validity of numerical results by MDPS is compared with commonly used rigorous coupled wave analysis for TM polarization. The numerical evidence shows the developed method has not only better stability but also higher efficiency.

Fig. 1. Simulation results of a metallic lamellar grating of pitch 0.25μm with index 3.18-4.41j deposited on glass substrate with TM-polarized wave 0.55μm. (a) The diffraction efficiencies T0 by RCWA and MDPS. The circle line is obtained by using RCWA, and the solid line by MDPS. (b) The retained orders dependence of convergence of diffraction efficiencies.

Fig. 2. Diffraction efficiency R−1 of a highly metallic lamellar grating of pitch 0.5μm with index -10j as the function of the groove width g. The wavelength is 632.8 nm. The solid curve is obtained by MDPS and the dash line by RCWA.

Fig. 3. (a) Amplitudes of the first two TM modal fields with real effective index in the grating. (b) Numerically calculated diffraction efficiencies as a function of grating thickness.

Y.-P. Chiou, W.-L. Yeh, and N.-Y. Shih, IEEE/OSA Journal of Lightwave Technology, 27,  Dec. 2009.


Experimental characterization of two-axis MEMS scanners with hidden radial vertical combdrive actuators and cross-bar spring structures

Professor Jui-che Tsai

Graduate Institute of Photonics and Optoelectronics, National Taiwan University

We perform the experimental characterization of two-axis MEMS scanners driven by radial vertical combdrive actuators (Figure 1). The dc scan ranges are limited by the pull-in effect. Each scanner utilizes a cross-bar spring structure to achieve two rotational degrees of freedom (DOFs) without employing any gimbal. Both the actuators and torsion springs are hidden underneath the mirror to obtain a small form factor. The devices are fabricated by a five-layer polysilicon surface micromachining process (SUMMiT-V). Devices with different combinations of parameter values are experimentally characterized and compared.

The optimal design (S1) comes with a balanced cross-bar spring structure. The mechanical rotation angles are ±5.30° (50.2V) and ±6.04° (52.8V) for rotations about the x and y axes, respectively (Figure 2). For each rotational mode, a significant angle is obtained under a reasonable bias voltage. The resonant frequencies are 11.4 kHz and 11 kHz.

Figure 1 (a) SEM photo of typical devices and (b) a close-up of the device with a circular mirror.

Figure 2 Comparison between the dc characteristics of three devices with balanced cross-bar spring structures.

© 2009 Institute of Physics (IOP) and IOP Publishing Ltd

J. C. Tsai et al., “Experimental characterization of two-axis MEMS scanners with hidden radial vertical combdrive actuators and cross-bar spring structures,” J. Micromech. Microeng., Vol. 19, No. 4, 045002, Apr. 2009.


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