Journals >Optoelectronics Letters
Contents
2016
Volume: 12 Issue 4
19 Article(s)
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Research Article
Fabrication of ordered micro- and nano-scale patterns based on optical discs and nanoimprint
Hui-jing GUO, Xiao-liang ZHANG, and Xiao-chun LI
A simple method to fabricate one-dimensional (1-D) and two-dimensional (2-D) ordered micro- and nano-scale patterns is developed based on the original masters from optical discs, using nanoimprint technology and soft stamps. Polydimethylsiloxane (PDMS) was used to replicate the negative image of the 1-D grating patternA simple method to fabricate one-dimensional (1-D) and two-dimensional (2-D) ordered micro- and nano-scale patterns is developed based on the original masters from optical discs, using nanoimprint technology and soft stamps. Polydimethylsiloxane (PDMS) was used to replicate the negative image of the 1-D grating pattern on the masters of CD-R, DVD-R and BD-R optical discs, respectively, and then the 1-D pattern on one of the PDMS stamps was transferred to a blank polycarbonate (PC) substrate by nanoimprint. The 2-D ordered patterns were fabricated by the second imprinting using another PDMS stamp. Different 2-D periodic patterns were obtained depending on the PDMS stamps and the angle between the two times of imprints. This method may provide a way for the fabrication of complex 2-D patterns using simple 1-D masters..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 241 (2016)
A higher performance dye-sensitized solar cell based on the modified PMII/EMIMBF4 binary room temperature ionic liquid electrolyte
Wu-yang WANG, Da-peng CAO, Chao WANG, Xiang-yu ZHANG, Bao-xiu MI, Zhi-qiang GAO, and Zhong-cheng LIANG
Additives and iodine (I2) are used to modify the binary room temperature ionic liquid (RTIL) electrolyte to enhance the photovoltaic performance of dye-sensitized solar cells (DSSCs). The short-circuit current density (JSC) of 17.89 mA/ cm2, open circuit voltage (VOC) of 0.71 V and fill factor (FF) of 0.50 are achievedAdditives and iodine (I2) are used to modify the binary room temperature ionic liquid (RTIL) electrolyte to enhance the photovoltaic performance of dye-sensitized solar cells (DSSCs). The short-circuit current density (JSC) of 17.89 mA/ cm2, open circuit voltage (VOC) of 0.71 V and fill factor (FF) of 0.50 are achieved in the optimal device. An average photoelectric conversion efficiency (PCE) of 6.35% is achieved by optimization, which is over two times larger than that of the parent device before optimization (2.06%), while the maximum PCE can reach up to 6.63%..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 245 (2016)
Effects of p-type GaN thickness on optical properties of GaN-based light-emitting diodes
Ming-sheng XU, Heng ZHANG, Quan-bin ZHOU, and Hong WANG
The influence of p-type GaN (pGaN) thickness on the light output power (LOP) and internal quantum efficiency (IQE) of light emitting diode (LED) was studied by experiments and simulations. The LOP of GaN-based LED increases as the thickness of pGaN layer decreases from 300 nm to 100 nm, and then decreases as the thicknThe influence of p-type GaN (pGaN) thickness on the light output power (LOP) and internal quantum efficiency (IQE) of light emitting diode (LED) was studied by experiments and simulations. The LOP of GaN-based LED increases as the thickness of pGaN layer decreases from 300 nm to 100 nm, and then decreases as the thickness decreases to 50 nm. The LOP of LED with 100-nm-thick pGaN increases by 30.9% compared with that of the conventional LED with 300-nm-thick pGaN. The variation trend of IQE is similar to that of LOP as the decrease of GaN thickness. The simulation results demonstrate that the higher light efficiency of LED with 100-nm-thick pGaN is ascribed to the improvements of the carrier concentrations and recombination rates..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 249 (2016)
A laser beam shaper for homogeneous rectangular illumination based on freeform micro lens array
En-guo CHEN, Jia-min HUANG, Tai-liang GUO, and Reng-mao WU
An effective design method of freeform micro lens array is presented for shaping varied laser beams into prescribed rectangular illumination. The variable separation mapping is applied to design concave freeform surfaces for constructing a freeform lens array. Several dedicated examples show that the designed freeform An effective design method of freeform micro lens array is presented for shaping varied laser beams into prescribed rectangular illumination. The variable separation mapping is applied to design concave freeform surfaces for constructing a freeform lens array. Several dedicated examples show that the designed freeform optical lens array can achieve a prescribed rectangular illumination pattern, especially without considering the initial states of incident laser beams. Both high collection efficiency and good spatial uniformity can be available simultaneously. Tolerance analysis is also performed to demonstrate that this optical device can well avoid fabricating difficulty in actual applications..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 253 (2016)
A novel polarization splitter based on octagonal dualcore photonic crystal fiber
Yong MA, Hui ZOU, and Wei WEI
A novel polarization splitter based on octagonal dual-core photonic crystal fiber (O-D-PCF) is proposed. The impacts of several fiber parameters on the coupling characteristics of the polarization splitter are investigated by full-vectorial finite element method (FV-FEM) in detail. Through optimizing the fiber configurA novel polarization splitter based on octagonal dual-core photonic crystal fiber (O-D-PCF) is proposed. The impacts of several fiber parameters on the coupling characteristics of the polarization splitter are investigated by full-vectorial finite element method (FV-FEM) in detail. Through optimizing the fiber configuration, a 4.267-mm-long polarization splitter with a bandwidth of 37 nm is achieved, and its extinction ratio (ER) is as high as 81.2 dB at the wavelength of 1.55 μm. Compared with the hexagonal dual-core photonic crystal fiber (H-D-PCF) based polarization splitter, both ER and bandwidth of the O-D-PCF based one are effectively improved..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 257 (2016)
A switchable and tunable ytterbium-doped fiber ring laser with a Sagnac loop mirror
Xiao-liang WANG, Da-ru CHEN, Xiao-wei MA, Hai-tao LI, and Shu-jun LUO
A switchable and tunable ytterbium-doped fiber ring laser (YDFL) is reported and demonstrated. Employing a Sagnac loop mirror fabricated by an 85-cm-long polarization-maintaining fiber (PMF), the proposed YDFL can operate with stable dual-wavelength lasing or tunable single-wavelength lasing around 1 064 nm. Both stablA switchable and tunable ytterbium-doped fiber ring laser (YDFL) is reported and demonstrated. Employing a Sagnac loop mirror fabricated by an 85-cm-long polarization-maintaining fiber (PMF), the proposed YDFL can operate with stable dual-wavelength lasing or tunable single-wavelength lasing around 1 064 nm. Both stable dual-wavelength lasing and tunable single-wavelength lasing are achieved by adjusting a polarization controller in the Sagnac loop mirror. The experimental results show that the output of the proposed fiber laser with two different operation modes is rather stable at room temperature..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 261 (2016)
Tunable and switchable dual-wavelength erbium-doped fiber laser based on in-line tapered fiber filters
Zheng-rong TONG, He YANG, and Ye CAO
A tunable and switchable dual-wavelength erbium-doped fiber laser (EDFL) based on all-fiber single-mode tapered fiber structure has been demonstrated. By adjusting the variable optical attenuator (VOA), the laser can be switched between the single-wavelength mode and the dual-wavelength mode. When the temperature appliA tunable and switchable dual-wavelength erbium-doped fiber laser (EDFL) based on all-fiber single-mode tapered fiber structure has been demonstrated. By adjusting the variable optical attenuator (VOA), the laser can be switched between the single-wavelength mode and the dual-wavelength mode. When the temperature applied on the tapered fiber structure varies, the pass-band varies and the wavelength of the output laser shifts correspondingly. When the temperature changes from 30 °C to 180 °C, the central wavelength of the EDFL generated by branch A shifts from 1 550.7 nm to 1 560.3 nm, while that of branch B shifts from 1 530.8 nm to 1 540.4 nm, indicating the wavelength interval is tunable. These advantages enable this laser to be a potential candidate for high-capacity wavelength division multiplexing systems and mechanical sensors..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 264 (2016)
Non-blocking four-port optical router based on thermooptic silicon microrings
Pei-pei DANG, Cui-ting LI, Wen-xue ZHENG, Chuan-tao ZHENG, and Yi-ding WANG
By using silicon-on-insulator (SOI) platform, 12 channel waveguides, and four parallel-coupling one-microring resonator routing elements, a non-blocking four-port optical router is proposed. Structure design and optimization are performed on the routing elements at 1 550 nm. At drop state with a power consumption of 0 By using silicon-on-insulator (SOI) platform, 12 channel waveguides, and four parallel-coupling one-microring resonator routing elements, a non-blocking four-port optical router is proposed. Structure design and optimization are performed on the routing elements at 1 550 nm. At drop state with a power consumption of 0 mW, the insertion loss of the drop port is less than 1.12 dB, and the crosstalk between the two output ports is less than -28 dB; at through state with a power consumption of 22 mW, the insertion loss of the through port is less than 0.45 dB, and the crosstalk between the two output ports is below -21 dB. Routing topology and function are demonstrated for the four-port optical router. The router can work at nine non-blocking routing states using the thermo-optic (TO) effect of silicon for tuning the resonance of each switching element. Detailed characterizations are presented, including output spectrum, insertion loss, and crosstalk. According to the analysis on all the data links of the router, the insertion loss is within the range of 0.13—3.36 dB, and the crosstalk is less than ?19.46 dB. The router can meet the need of large-scale optical network- on-chip (ONoC)..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 268 (2016)
A compact triple-band bandpass filter based on metamaterials
Ya-juan ZHAO, Bo JIANG, Bao-yi LI, and Dong-hong WANG
This paper presents a compact triple-band bandpass filter based on metamaterials. The miniaturization is realized by the principle of phase compensation of metamaterial. Compared with the conventional half-wavelength filter, the metamaterial filter has a small size of 10 mm×10 mm. The triple-band bandpass filter pThis paper presents a compact triple-band bandpass filter based on metamaterials. The miniaturization is realized by the principle of phase compensation of metamaterial. Compared with the conventional half-wavelength filter, the metamaterial filter has a small size of 10 mm×10 mm. The triple-band bandpass filter performance has been validated by the electromagnetic simulation software of high frequency structure simulator (HFSS). The results illustrate that the filter is designed with center frequencies of 2.4 GHz, 5.1 GHz and 8.8 GHz, bandwidths of about 7.9% (2.31.2.50 GHz), 7.8% (5.0.5.4 GHz) and 7.4% (8.50.9.15 GHz), respectively, and it shows good band pass characteristics..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 273 (2016)
Dual-band bandpass tunable microwave photonic filter based on stimulated Brillouin scattering
Jia-qi LI, Yong-chuan XIAO, Wei DONG, and Xin-dong ZHANG
A dual-band bandpass microwave photonic filter (MPF) based on stimulated Brillouin scattering (SBS) is theoretically analyzed and experimentally demonstrated. Two separated tunable laser sources (TLSs) are employed to generate two passbands by implementing phase modulation to amplitude modulation conversion by using SBA dual-band bandpass microwave photonic filter (MPF) based on stimulated Brillouin scattering (SBS) is theoretically analyzed and experimentally demonstrated. Two separated tunable laser sources (TLSs) are employed to generate two passbands by implementing phase modulation to amplitude modulation conversion by using SBS induced sideband amplification. The center frequencies of both passbands can be independently tuned ranging from 1 GHz to 19 GHz. High resolution with 3 dB bandwidth less than 30 MHz and large out-of-band rejection about 40 dB under 25 mW optical pump power are achieved..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 276 (2016)
Microstructure and optoelectronic properties of galliumtitanium-zinc oxide thin films deposited by magnetron sputtering
Shou-bu CHEN, Zhou LU, Zhi-you ZHONG, Hao LONG, Jin-hua GU, and Lu LONG
Gallium-titanium-zinc oxide (GTZO) transparent conducting oxide (TCO) thin films were deposited on glass substrates by radio frequency magnetron sputtering. The dependences of the microstructure and optoelectronic properties of GTZO thin films on Ar gas pressure were observed. The X-ray diffraction (XRD) and scanning eGallium-titanium-zinc oxide (GTZO) transparent conducting oxide (TCO) thin films were deposited on glass substrates by radio frequency magnetron sputtering. The dependences of the microstructure and optoelectronic properties of GTZO thin films on Ar gas pressure were observed. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results show that all the deposited films are polycrystalline with a hexagonal structure and have a preferred orientation along the c-axis perpendicular to the substrate. With the increment of Ar gas pressure, the microstructure and optoelectronic properties of GTZO thin films will be changed. When Ar gas pressure is 0.4 Pa, the deposited films possess the best crystal quality and optoelectronic properties..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 280 (2016)
Stress control of silicon nitride films deposited by plasma enhanced chemical vapor deposition
Dong-ling LI, Xiao-fei FENG, Zhi-yu WEN, Zheng-guo SHANG, and Yin SHE
Stress controllable silicon nitride (SiNx) films deposited by plasma enhanced chemical vapor deposition (PECVD) are reported. Low stress SiNx films were deposited in both high frequency (HF) mode and dual frequency (HF/LF) mode. By optimizing process parameters, stress free (-0.27 MPa) SiNx films were obtained with theStress controllable silicon nitride (SiNx) films deposited by plasma enhanced chemical vapor deposition (PECVD) are reported. Low stress SiNx films were deposited in both high frequency (HF) mode and dual frequency (HF/LF) mode. By optimizing process parameters, stress free (-0.27 MPa) SiNx films were obtained with the deposition rate of 45.5 nm/min and the refractive index of 2.06. Furthermore, at HF/LF mode, the stress is significantly influenced by LF ratio and LF power, and can be controlled to be 10 MPa with the LF ratio of 17% and LF power of 150 W. However, LF power has a little effect on the deposition rate due to the interaction between HF power and LF power. The deposited SiNx films have good mechanical and optical properties, low deposition temperature and controllable stress, and can be widely used in integrated circuit (IC), micro-electro-mechanical systems (MEMS) and bio-MEMS..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 285 (2016)
High-quality pulse compression in a novel architecture based on a single-mode fiber cascading a nonlinear optical loop mirror
Yong-zhao XU, Jian-xun SONG, Geng ZHANG, Min-xia LIU, and Dong-xiong LING
A novel all-fiber low-pedestal pulse compression scheme is proposed and investigated. The scheme is based on an anomalously dispersive single-mode fiber (SMF) cascading a nonlinear optical loop mirror (NOLM) with another anomalously dispersive SMF in the loop. Numerical results show that excellent pulse compression andA novel all-fiber low-pedestal pulse compression scheme is proposed and investigated. The scheme is based on an anomalously dispersive single-mode fiber (SMF) cascading a nonlinear optical loop mirror (NOLM) with another anomalously dispersive SMF in the loop. Numerical results show that excellent pulse compression and pedestal reduction can be achieved by using the proposed scheme..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 290 (2016)
Performance analysis of relay-aided free-space optical communication system over gamma-gamma fading channels with pointing errors
Hui-hua FU, Ping WANG, Ran-ran WANG, Xiao-xia LIU, Li-xin GUO, and Yin-tang YANG
The average bit error rate (ABER) performance of a decode-and-forward (DF) based relay-assisted free-space optical (FSO) communication system over gamma-gamma distribution channels considering the pointing errors is studied. With the help of Meijer's G-function, the probability density function (PDF) and cumulativeThe average bit error rate (ABER) performance of a decode-and-forward (DF) based relay-assisted free-space optical (FSO) communication system over gamma-gamma distribution channels considering the pointing errors is studied. With the help of Meijer's G-function, the probability density function (PDF) and cumulative distribution function (CDF) of the aggregated channel model are derived on the basis of the best path selection scheme. The analytical ABER expression is achieved and the system performance is then investigated with the influence of pointing errors, turbulence strengths and structure parameters. Monte Carlo (MC) simulation is also provided to confirm the analytical ABER expression..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 294 (2016)
A real-time VLC to UART protocol conversion system
Jian-zhi DENG, Meng YAO, Xiao-hui CHENG, and Zhuo-hong DENG
A real-time visible light communication (VLC) to universal asynchronous receiver/transmitter (UART) conversion system is made up of a transmitter with a light emitting diode (LED) and a receiver with a photodiode (PD), by which a VLC system is connected to traditional communication modes, and the data are transferred bA real-time visible light communication (VLC) to universal asynchronous receiver/transmitter (UART) conversion system is made up of a transmitter with a light emitting diode (LED) and a receiver with a photodiode (PD), by which a VLC system is connected to traditional communication modes, and the data are transferred by wireless visible light. UART packets are converted to light packets by the modulation of a 10 kHz on-off-keying (OOK) light signal, and the data losses in the transportation are avoided by the protection of a data buffer mechanism. The experimental results reveal that the real-time VLC to UART conversion system can provide a real-time VLC transmission way for two UART devices in not less than 10 m at a baud rate not less than 19 200 Bd with stable ambient lighting at the same time..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 299 (2016)
Long reach DWDM-PON with 12.5 GHz channel spacing based on comb source seeding
Zhao ZHOU, Hai-tao NIE, and Yao-jun WANG
A long reach dense wavelength division multiplexing passive optical network (DWDM-PON) with 12.5 GHz channel spacing is proposed and experimentally demonstrated. An optical frequency comb source is used to provide the multiwavelength seeding light, while reflective semiconductor optical amplifiers (RSOAs) are installedA long reach dense wavelength division multiplexing passive optical network (DWDM-PON) with 12.5 GHz channel spacing is proposed and experimentally demonstrated. An optical frequency comb source is used to provide the multiwavelength seeding light, while reflective semiconductor optical amplifiers (RSOAs) are installed in both optical line terminal (OLT) and optical network units (ONUs) as colorless transmitter. The experimental results show that the bidirectional transmission for 1.2 Gbit/s data rate is achieved over 80 km single mode fiber (SMF)..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 304 (2016)
Formaldehyde gas sensor based on TiO2 thin membrane integrated with nano silicon structure
Xuan ZHENG, An-jie MING, Li YE, Feng-hua CHEN, Xi-long SUN, Wei-bing LIU, Chao-bo LI, Wen OU, Wei-bing WANG, and Da-peng CHEN
An innovative formaldehyde gas sensor based on thin membrane type metal oxide of TiO2layer was designed and fabricated. This sensor under ultraviolet (UV) light emitting diode (LED) illumination exhibits a higher response to formaldehyde than that without UV illumination at low temperature. The sensitivities of the senAn innovative formaldehyde gas sensor based on thin membrane type metal oxide of TiO2layer was designed and fabricated. This sensor under ultraviolet (UV) light emitting diode (LED) illumination exhibits a higher response to formaldehyde than that without UV illumination at low temperature. The sensitivities of the sensor under steady working condition were calculated for different gas concentrations. The sensitivity to formaldehyde of 7.14 mg/m3is about 15.91 under UV illumination with response time of 580 s and recovery time of 500 s. The device was fabricated through micro-electro-mechanical system (MEMS) processing technology. First, plasma immersion ion implantation (PIII) was adopted to form black polysilicon, then a nanoscale TiO2membrane with thickness of 53 nm was deposited by DC reactive magnetron sputtering to obtain the sensing layer. By such fabrication approaches, the nanoscale polysilicon presents continuous rough surface with thickness of 50 nm, which could improve the porosity of the sensing membrane. The fabrication process can be mass-produced for the MEMS process compatibility..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 308 (2016)
An optic fiber sensor for multiple gases based on fiber loop ring-down spectroscopy and microring resonator arrays
Xin ZHANG, Jia-wen JIAN, Yan-gong ZHENG, Han JIN, and Jie ZOU
A high-sensitivity sensor for multiple gases based on microring array filter and fiber loop ring-down spectroscopy system is proposed and demonstrated. The parameters of the resonators are designed so that the filtered signal from a broadband light source can be tuned with an absorption spectral line of gas. Therefore,A high-sensitivity sensor for multiple gases based on microring array filter and fiber loop ring-down spectroscopy system is proposed and demonstrated. The parameters of the resonators are designed so that the filtered signal from a broadband light source can be tuned with an absorption spectral line of gas. Therefore, through adding microring resonators horizontally and vertically, the number of target gases and filter range are increased. In this research, in the broad spectral range of about 0.9 μm, only the absorption spectral lines of target gases are filtered. The simulation results show that three target gases, CH4, CO2and HF, can be simultaneously detected by the sensing system. Owing to the fiber loop ring-down spectroscopy, the whole system is optimized in mini-size and sensitivity, and we can choose different sensing methods to enhance the measurement accuracy for high and low concentration conditions..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 312 (2016)
Fast prediction unit selection method for HEVC intra prediction based on salient regions
Lei FENG, Ming DAI, Chun-lei ZHAO, and Jing-ying XIONG
In order to reduce the computational complexity of the high efficiency video coding (HEVC) standard, a new algorithm for HEVC intra prediction, namely, fast prediction unit (PU) size selection method for HEVC based on salient regions is proposed in this paper. We first build a saliency map for each largest coding unit In order to reduce the computational complexity of the high efficiency video coding (HEVC) standard, a new algorithm for HEVC intra prediction, namely, fast prediction unit (PU) size selection method for HEVC based on salient regions is proposed in this paper. We first build a saliency map for each largest coding unit (LCU) to reduce its texture complexity. Secondly, the optimal PU size is determined via a scheme that implements an information entropy comparison among sub-blocks of saliency maps. Finally, we apply the partitioning result of saliency map on the original LCUs, obtaining the optimal partitioning result. Our algorithm can determine the PU size in advance to the angular prediction in intra coding, reducing computational complexity of HEVC. The experimental results show that our algorithm achieves a 37.9% reduction in encoding time, while producing a negligible loss in Bjontegaard delta bit rate (BDBR) of 0.62%..
Optoelectronics Letters
- Publication Date: Jan. 01, 1900
- Vol. 12, Issue 4, 316 (2016)
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