An optical receiver for eight-level data communication over step index plastic optical fiber

An optical receiver with automatic-gain-control transimpedance amplifier, linear post amplifier and linear line driver suitable for multilevel signals is presented. A large-diameter photodiode (400 μm) with an antireflection coating optimized for red light was integrated. These features enable the presented optical receiver to be a promising plastic optical fiber receiver. An error free (<10⁻⁸) 400 Mbit/s data rate over 50 m PMMA-step index plastic optical fiber (1 mm diameter) is achieved with eight-level pulse amplitude modulation (8-PAM).     

Realization of optoelectronic integrated transmitter and receiver for POF Applications

The optoelectronic integrated transmitter and receiver for 650 nm plastic optical fiber (POF) communication applications realized in 0.5 μm BCD (Biplor, CMOS and DMOS) process is first described in this paper. The 650 nm resonant cavity light emitting diode (RCLED) is used as light source. It is first proposed for optoelectronic integration of the transmitter by bonding RCLED to the driver chip. Temperature compensation technology is employed in the driver circuit to compensate for the modulation current. In the monolithic optoelectronic integrated receiver, large area multi-finger PIN photodetector (PD) that is compatible with standard IC process, transimpedance amplifier and post amplifier are presented. Measurement results show that the responsivity and capacitance of PD is 0.25 A/W and 5 pF, respectively. The sensitivity of receiver is −14.6 dBm at 180 Mb/s and BER is less than 10⁻⁹ for 650 nm input light by POF. A clear eye diagram is demonstrated for 180 Mb/s PRBS. These indicate that optoelectronic integrated chips can be employed in high-speed POF-based Fast Ethernet systems for broadband access network applications.     

170 Mb/s multilevel transmission over 115 m standard step-index plastic optical fiber using an integrated optical receiver

An optical receiver having a high linearity is used for multilevel communication over standard step plastic optical fiber. A large-diameter photodiode with an antireflection coating optimized for red light was integrated. These features enable the used optical receiver to be a promising plastic optical fiber receiver. An error free (< 10⁻⁸) 170 Mb/s data rate over 115 m standard PMMA step-index plastic optical fiber is achieved with four-level and eight-level pulse amplitude modulation.     

Design and performance of a plastic optical fiber leakage sensor

In this article design and operation of a plastic optical fiber (POF) sensor based on the unconventional light leakage from one fiber to another one causing intensity modulation are presented. The dominant loss mechanism was found to be the evanescent loss and based on this phenomenon the optical fiber sensor was designed. The penetration depth of evanescent wave as a function of different refractive index of cladding was calculated. Operation of this sensor was tested as a liquid level sensor for different liquids and the experimental results are compared. The dry (air interface layer) and wet output (liquid interface layer) signals for this probe were measured for a series of measurements and important factors concerning sensor operation are described. The precision of measured values, reproducibility of the results (1.35% error), and the stability of sensing operation as a function of time at different launching powers are also reported (0.85% error). The reported results for this design are promising and verify the successful operation of such a device as a liquid level probe and also as an on/off level switch.     

Surface structure monitoring with plastic optical fiber

A sensor was designed using a plastic optical fiber to study the potential of detecting structural deformities and corrosion of metallic surfaces, in particular for applications in constricted areas such as pipes. The principle of the sensor is based on the collection of scattered light reflected by the surface imperfections. Several types of metallic materials in various surface profiles and stages of corrosion have been studied. The sensor was able to determine the position of ridges on the surface and corroded regions in all cases evaluated in the study. A sensitivity of 100 mV/mm was detectable for proximity and a vertical resolution of 1 mm has been measured.     

超短光脉冲在光纤中传输计算机模拟计算的研究

本文提出了一种研究超短光脉冲在介质中传输特性的简单的计算机计算方法.用该方法得到了正色散光纤中的频率调制、频谱加宽和方波自成形,以及负色散光纤中的一、二、三阶孤子传输.其数值计算结果与解非线性薛定谔方程的数值结果完全一致.     

光纤-光栅对激光脉冲压缩

本文报道用2m单模保偏光纤实现脉冲光谱加宽,经光栅对补偿后,将40ps脉冲压缩到小于10ps的实验结果,分析了影响光脉冲压缩质量的原因。实验结果与理论较好地吻合。     

A novel bits loading algorithm for adaptive modulation OFDM multimode fiber communication system

A novel bits loading algorithm is proposed for adaptively modulated optical OFDM (AMOOFDM) multimode fiber communication system to decrease the system bit error rate (BER) caused by some OFDM subcarriers located at the deep nulls in the high frequency region of multimode fiber. The simulation results show that the performance of the new algorithm is approximate to the optimal algorithm-Greedy algorithm, but its computational complexity is considerably lower, thus the new algorithm is easy to implement. Comparing to fixed bits loading, adaptive bits loading can reduce the system BER effectively.     

Pre-amp EDFA ASE noise minimization for optical receiver transmission performance optimization

Amplified spontaneous emission (ASE) noise mitigation from the pre-amp erbium-doped fiber amplifier (EDFA) to the photon detector (PD) in optical receivers can be reduced by optimizing the EDFA at the optical receiver level to achieve optimal optical receiver transmission performance.     

1 Gbit/s transmission over step-index plastic optical fiber using an optical receiver with an integrated equalizer

A single chip optical receiver with an integrated large-diameter photodiode, transimpedance amplifier, two stages active equalizer, post amplifier and 50 Ω driver is used for gigabit transmission over PMMA step plastic optical fiber (SI-POF). The large-diameter photodiode with an antireflection coating optimized for red light. The integrated equalizer enables the presented optical receiver to reach 1 Gbit/s over 50 m SI-POF at bit error ratio of 10^− 6. An error free (< 10^− 9) 1 Gbit/s data rate over 40 m standard PMMA step-index plastic optical fiber is also achieved.     

光学PAM-PDM转换:光学临界慢变效应的一种应用

基于光学临界慢变效应对光学双稳器件本文提出了一种新的功能——光学脉冲振幅调制(PAM)到光学脉冲持续时间调制(PDM)的转换,并且在实验上证实了这种功能的可行性.     

Design and optimization of novel ultra-compact SOI multimode interference optical switch

In this paper, an ultra-compact 3 × 3 SOI multimode interference optical switch is presented. There is only one hyperbolic multimode waveguide in the switch. By changing the refractive index of one or two parts within the hyperbolic multimode waveguide, the switch can realize on and off functions between any pair of input and output ports. The various states of the switch were simulated and analyzed using the finite difference beam propagation method (FD-BPM), the structure parameters of the switch were also designed and optimized. The optimized switch has excellent properties and the whole size of the switch is less than 4 mm.     

Sol-gel matrix modified microstructured optical fibre towards a fluoride sensitive optical probe

In this article, we report an optical fluoride probe based on microstructured polymer optical fibers (MPOFs) which is modified with morin-Al complex doped silica gel film. This probe is fabricated by sol-gel fluxion coating process. Sol solution doped with morin-Al is directly inhaled into array holes of MPOF and then forms morin-Al-gel matrix film in them. The sensing probe shows different fluorescence intensity to different fluoride ion concentrations in the aqueous solution. The range of response is 5-50 mmol/L, under the condition of pH 4.6.     

Calculation of the frequency response in step-index plastic optical fibers using the time-dependent power flow equation

The time-dependent power flow equation, which is reduced to its time-independent counterpart is employed to calculate frequency response and bandwidth in addition to mode coupling and mode-dependent attenuation in a step-index plastic optical fiber. The frequency response is specified as a function of distance from the input fiber end. This is compared to reported measurements. Mode-dependent attenuation and mode dispersion and coupling are known to be strong in plastic optical fibers, leading to major implications for their frequency response in data transmission systems.     

Adaptive Bit allocation algorithm based on unsaturated bandwidth of multimode fiber for optical OFDM system

An adaptive bit allocation algorithm for Orthogonal Frequency Division Multiplexing (OFDM) multimode fiber communication system is proposed in this paper, aimed at utilizing the infinite bandwidth of multimode fiber in high frequency region. The algorithm breaks through the limitation that bits are formerly allocated only in fixed bandwidth, and is proved to be effective by simulation. Compared with greedy algorithm, new algorithm is easy to implement, and lowers bit error rate (BER) of each subcarrier effectively.     

基于单模光纤的交叉相位调制型频率分辨光学开关超短脉冲测量

利用单模光纤中的光弹效应和交叉相位调制(XPM)效应,提出了一种频率分辨光学开关法测量超短脉冲的新方案.在本方案中,单模光纤的前一部分产生可变延迟,后一部分作为非线性介质产生非线性效应.该方案只需一根单模光纤,无须复杂的光路校准,结构简单,损耗低;光纤中的XPM效应易发生,无须相位匹配.对提出的方案进行了数值模拟,采用基于矩阵的主元素广义投影算法,恢复出待测脉冲的幅度和相位信息,并研究了光纤长度和待测超短脉冲的脉冲宽度对测量结果的影响.结果表明:测量准确度随着光纤长度的增加而提高,选取长度为2 km的光纤,就可以实现对超短脉冲的准确测量;本文方案适用于脉冲宽度不小于80 fs的超短光脉冲的测量.     

All optical SR and D flip-flop employing XGM effect in semiconductor optical amplifiers

This paper presents a simple and novel scheme for all-optical SR and D flip-flop employing cross gain modulation (XGM) effect in two wideband semiconductor optical amplifiers. The proposed flip-flop has a fast response, with less than 20 ps transition times for both rising and falling edges. The FF speed-limit is mainly determined by the SOA recovery time and the intra-FF coupling length. The simulation results exhibit a contrast ratio of 13 dB between two states with an AM of less than 2.5 dB.The distinctive simplicity of the flip-flop implies reduced footprint and low power consumption which makes it ideal for photonic integration.     

Theoretical analysis of pattern effect suppression in semiconductor optical amplifier utilizing optical delay interferometer

The ability of an optical delay interferometer (ODI) to suppress the pattern effect that is inherently present in a straightforward, solitary semiconductor optical amplifier (SOA) whose dynamic response is slower than the period of its driving high-speed return-to-zero (RZ) data signal is theoretically investigated. For this purpose an existing comprehensive model that simulates and links the operation of these two elements is methodically applied to their concatenated configuration. In this manner an extensive set of curves is numerically obtained, which allow to analyze and assess the impact of the input pulse energy and width as well as of the SOA carrier lifetime, linewidth enhancement factor and small signal gain on the amplitude modulation of the transmitted sequence at the output of each one of these block units. Their thorough study and interpretation reveals that the employment of the ODI can significantly reduce the value of this quality metric resulting from a single SOA only. The main offered benefit, however, is that any technical restrictions regarding the involved critical parameters can be considerably relaxed while at the same time their useful operational range can be extended. These important findings highlight the necessity of placing this passive device after the SOA and exploiting it in order to effectively alleviate the detrimental pattern-dependent degradation. This fact in conjunction with its overall practicality renders it a promising candidate for enhancing, within the frame of the proposed scheme, the performance of SOAs that are employed as pure amplification elements in fiber-optic communication systems and networking applications.     

4.25 Gbps小型可热插拔光收发模块的设计与测试

对4.25 Gbps小型化可热插拔(SFP)光收发模块的关键参数进行了理论分析,从发射、接收和控制3个方面讨论了模块的结构组成,设计出了符合SFP MSA及SFF-8472协议的光模块,并根据此设计方案制作了样品模块。在-40,25,85 ℃环境温度下测试和分析了模块的性能指标,结果显示其光功率、消光比和灵敏度等均符合设计要求,且在适用温度范围内表现出良好的稳定性。实验证实了方案的可行性,为模块的产品化提供了参考。