Plastic Optical Fiber Communication Research Articles

650-nm vertical-cavity surface-emitting lasers (VCSELs) for plastic optical fiber communication

Vertical-cavity surface-emitting lasers (VCSELs) are widely used as light sources for high-speed communications. This is mainly due to their economical cost, high bandwidth, and scalability. However, efficient red VCSELs with emissions at 650 nm are required for plastic optical fiber (POF) technology because of the low-loss transmission window centered around this wavelength. This study investigates using 650-nm red VCSEL arrays in interconnected systems for POF communication to improve signal quality and increase data rates. The experimental results show that using one red VCSEL with a –3-dB bandwidth of 2 GHz in POF communication can achieve data rates of up to 4.7 Gb/s with 2 pJ/bit power efficiency using direct current-biased optical orthogonal frequency-division multiplexing (DCO-OFDM). The bit error ratio (BER) is 3.6×10−3, which is less than the hard-decision forward-error correction (FEC) limit of 3.8 × 10−3. In addition, temperature dependence measurements of the VCSEL have been presented from 15 ∘C to 38 ∘C. The essential parameters of VCSEL have also been measured: the maximum optical power is 2.5 mW, and the power conversion efficiency is 14%.

Performance evaluation of plastic optical fiber communication using micro-lens coupling and computational temporal ghost imaging algorithm.

Plastic optical fiber communication (POFC) systems are particularly sensitive to signal performance and power budget. In this paper, we propose what we belive to be a novel scheme to jointly enhance the bit-error-ratio (BER) performance and coupling efficiency for multi-level pulse amplitude modulation (PAM-M) based POFC systems. The computational temporal ghost imaging (CTGI) algorithm is developed for PAM4 modulation for the first time to resist the system distortion. The simulation results reveal that enhanced BER performance and clear eye diagrams are acquired by using CTGI algorithm with an optimized modulation basis. Experimental results also investigate and show, with CTGI algorithm, the BER performance for 180 Mb/s PAM4 signals is enhanced from 2.2 × 10-2 to 8.4 × 10-4 over 10 m POF by using a 40 MHz photodetector. The POF link is equipped with micro-lenses at its end faces by using a ball-burning technique, which helps to increase the coupling efficiency from 28.64% to 70.61%. Both simulation and experimental results show that the proposed scheme is feasible to achieve a cost-effective and high-speed POFC system with short reach.

Bandwidth Analysis of High-Speed InGaN Micro-LEDs by an Equivalent Circuit Model

High-speed light-emitting diodes (LEDs) are ideal light sources for low-cost plastic optical fiber communication in data-centers and vehicles. Here, high-speed micro-LEDs based on InGaN quantum dot (QD) active region with different diameters are fabricated and characterized. The -3dB bandwidth around 3.6 GHz and 1.4 GHz are achieved in the blue and green micro-LEDs under current density less than 1 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , respectively, which can work at an environmental temperature of 125 °C. An equivalent circuit model is proposed to analyze the limiting factors of the bandwidth, using which the effects of carrier recombination and RC time constant on modulation bandwidth are separated. It is found that carrier recombination rate is fast enough and the RC constant is still the main limiting factor for the blue micro-LEDs at an injection current density of more than 500 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> even when the diameter scales down to 20 μm, while the recombination rate mainly limits the bandwidth of the green micro-LEDs.

Evaluation of Radio over Plastic Optical Fiber Communications

In this work, we have experimentally evaluated the performance of a Radio over Plastic Optical Fiber (RoPOF) communications link by simultaneously transmitting Long-Term Evolution (LTE) and Narrow-Band Internet of Things (NB-IoT) signals over 75-meters of PMMA large-core Graded-Index POF (GI-POF).

Muhammad Waseem - Evaluation of Radio over Plastic Optical Fiber Communications

Evaluation of Radio over Plastic Optical Fiber Communications

Temperature insensitive low-loss optical connection for automotive gigabit plastic optical fiber communication

Step-index plastic optical fibers (SI-POFs) have already been implemented in automotive optical communication because they offer some significant advantages; they are free from electromagnetic noise and are appropriate for reliable data transmission in harsh environment applications. In current systems, an air gap exists between the fiber connections, and the gap size changes because of temperature variations. We propose and demonstrate an approach for the SI-POF in-line connection, which is targeted for automotive gigabit optical communication. We designed and fabricated an up-tapered ferrule and inserted an index matching material into the gap. By using the up-tapered ferrule, we obtained more stable insertion loss, which is proven by the heat cycle tests. By inserting the index matching material, the insertion loss becomes lower. Moreover, an encircled angular flux evaluation also confirmed that our approach does not change the modal power distribution of the fiber.

GaN-Based Cyan Light-Emitting Diode with up to 1-GHz Bandwidth for High-Speed Transmission Over SI-POF

We demonstrate the performance of a novel cyan light-emitting diode (LED) on a patterned sapphire substrate for use as a light source for plastic optical fiber (POF) communications with the central wavelength at 500 nm. By significantly reducing the number of active InxGa1-xN/GaN multiple quantum wells and the thickness of the barrier layers down to 5 nm, such a device with an active diameter of 47 μm demonstrates a record high 3-dB electrical-to-optical bandwidth, as high as 1 and 0.7 GHz, among all the reported high-speed visible LEDs under room temperature and 110 °C operation, respectively. TO-Can packaging with a lens is used to enhance the POF coupling efficiency. Very-high data rates of 5.5 and 5.8 Gbit/s are achieved over step index POF under nonreturn-to-zero and 4-pulse amplitude modulation, respectively. When the POF transmission distance reaches 50 m, there is degradation in the maximum data rate for both modulation schemes to 1.3 Gbit/s due to the dispersion and attenuation of the POF.

High-Speed Nonpolar InGaN/GaN LEDs for Visible-Light Communication

Free-standing nonpolar GaN substrates provide an excellent platform for the fabrication of high-speed blue and green light-emitting diodes (LEDs), which are attractive for visible-light communication, plastic optical fiber communication, and short-range under water optical communication. Nonpolar LEDs on free-standing GaN exhibit a large electron-hole wave function overlap, low extended defect density, and favorable thermal properties. Here, we demonstrate high-speed nonpolar InGaN/GaN LEDs with a peak emission wavelength between 455 and 465 nm on free-standing nonpolar GaN substrates. A large frequency modulation bandwidth of 524 MHz is demonstrated at a current density of 10 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

AlGaInN laser diode technology for GHz high-speed visible light communication through plastic optical fiber and water

AlGaInN ridge waveguide laser diodes are fabricated to achieve single-mode operation with optical powers up to 100 mW at ∼420 nm for visible free-space, underwater, and plastic optical fiber communication. We report high-frequency operation of AlGaInN laser diodes with data transmission up to 2.5 GHz for free-space and underwater communication and up to 1.38 GHz through 10 m of plastic optical fiber.

The Blue LED Nobel Prize: Historical context, current scientific understanding, human benefit

The Blue LED Nobel Prize: Historical context, current scientific understanding, human benefit

High-Speed Light-Emitting Diodes Emitting at 500 nm With 463-MHz Modulation Bandwidth

Light-emitting diode (LED) is one of the most important light sources due to its low power consumption and long lifetime. In this letter, we present the high-frequency characteristics of GaN-based green LEDs with different aperture diameters. In order to get higher current density, we use ring-shaped electrode to confine the current injection. Unlike conventional LEDs, we only use its natural feature to get a high modulation bandwidth. The LEDs investigated have a peak emission wavelength of 500 nm. The highest optical 3-dB modulation bandwidth is ~463 MHz at 50 mA for the 500-nm green GaN-based LED with an aperture diameter of 75 μm. It is the highest bandwidth yet reported for the green GaN-based LEDs. The LED also exhibits a relatively high output power of ~1.6 mW at 50 mA as compared with other high-speed LEDs. Such the LEDs can be applied to plastic optical fiber and visible light communication in the future.

Realization of optoelectronic integrated transmitter and receiver for POF Applications

The optoelectronic integrated transmitter and receiver for 650nm plastic optical fiber (POF) communication applications realized in 0.5μm BCD (Biplor, CMOS and DMOS) process is first described in this paper. The 650nm 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 0.25A/W and 5pF, respectively. The sensitivity of receiver is −14.6dBm at 180Mb/s and BER is less than 10−9 for 650nm input light by POF. A clear eye diagram is demonstrated for 180Mb/s PRBS. These indicate that optoelectronic integrated chips can be employed in high-speed POF-based Fast Ethernet systems for broadband access network applications.

塑料光纤通信650 nm单片集成光接收芯片研究

A 650 nm monolithic optical receiver for plastic optical fiber communication is proposed,including a photodetector,a tranimpedance preamplifier,a single to differential conversion,a cascade of differential amplifiers,an output buffer and an offset voltage compensation.Based on reasonable assumption and approximation,the spectral response of photodetector is analyzed according to its steady-state continuity equation and boundary conditions.Analysis of frequency response is established due to the basic equations of the photodetector by Laplace transform method.The layout area of monolithic optical receiver is about 832×948μm2 with 0.5μm BCD process.Measurement results indicate that the responsivity of photodetector is 0.26A/W for 650nm at 5Vreverse bias.The sensitivity is-14.6dBm at 180Mbps and bit error rate less than 10-9.A clear eye diagram is demonstrated for 100Mbps pseudorandom binary sequence and bit error rate less than 10-9.

GaN-Based Miniaturized Cyan Light-Emitting Diodes on a Patterned Sapphire Substrate With Improved Fiber Coupling for Very High-Speed Plastic Optical Fiber Communication

We demonstrate the performance of a novel cyan light-emitting diode (LED) on a patterned sapphire (PS) substrate as a light source for plastic optical fiber (POF) communications with the central wavelength at 500 nm. To further enhance the external quantum efficiency (EQE) and output power of this miniaturized high-speed LED, a LED with a PS substrate is adopted. Furthermore, by greatly reducing the number of active <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\hbox{In}_{\rm x}\hbox{Ga}_{1 - {\rm x}}\hbox{N/GaN}$</tex></formula> multiple quantum wells (MQWs) to four and minimizing the device active area, we can achieve a record-high electrical-to-optical (E–O) bandwidth (as high as 400 MHz) among all the reported high-speed visible LEDs under a very small dc bias current (40 mA). The fiber coupling efficiency has been improved in 4 dB using lens with a 500- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu \hbox{m}$</tex></formula> diameter mounted on the LED chip. Thus, the maximum fiber-coupled power was <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex></formula> 2.67 dBm at the bias current of 40 mA. The 1.07-Gb/s data transmissions over a 50-m SI-POF fiber have been successfully demonstrated using this device at the bias current of 40 mA.

Very-High Temperature (200 $^{\circ}$C) and High-Speed Operation of Cascade GaN-Based Green Light- Emitting Diodes With an InGaN Insertion Layer

We demonstrate a novel type of linear cascade green light-emitting diode (LED) arrays as a light source for in-car or harsh environment plastic optical fiber (POF) communications. To further enhance its dynamic and static performance, an InGaN layer is inserted between an n-type GaN cladding layer and InGaN-GaN multiple quantum wells as an efficient current spreading layer. Compared with the control device without that layer, our three-LED cascade array demonstrates a smaller turn-on voltage (9.3 versus 11 V at 20 mA) and a larger output power (25.5 versus 22.5 mW at 180 mA), corresponding to an enhancement of around 31% in wall-plug efficiency. Furthermore, under the constant voltage bias of an in-car battery (12 V), our three-LED array exhibits an electrical-to-optical 3-dB bandwidth (100 versus 40 MHz) performance superior to that of the control device. Even under high-temperature dynamic operation, we observe that the InGaN insertion layer gives strong enhancement of modulation speed with negligible degradation of the output power, unlike the red resonant-cavity LEDs conventionally used for POF. We achieve 200-Mb/s error-free transmission at 200°C which is the highest operation temperature among all the reported high-speed LEDs.

Effect of SiO 2/Si 3N 4 dielectric distributed Bragg reflectors (DDBRs) for Alq 3/NPB thin-film resonant cavity organic light emitting diodes

In this article, we report on the effect of SiO 2/Si 3N 4 dielectric distributed Bragg reflectors (DDBRs) for Alq 3/NPB thin-film resonant cavity organic light emitting diode (RCOLED) in increasing the light output intensity and reducing the linewidth of spontaneous emission spectrum. The optimum DDBR number is found as 3 pairs. The device performance will be bad by further increasing or decreasing the number of DDBR. As compared to the conventional Alq 3/NPB thin-film organic light emitting diode (OLED), the Alq 3/NPB thin-film RCOLED with 3-pair DDBRs has the superior electrical and optical characteristics including a forward voltage of 6 V, a current efficiency of 3.4 cd/A, a luminance of 2715 cd/m 2 under the injection current density of 1000 A/m 2, and a full width at half maximum (FWHM) of 12 nm for emission spectrum over the 5–9 V bias range. These results represent that the Alq 3/NPB thin-film OLED with DDBRs shows a potential as the light source for plastic optical fiber (POF) communication system.

High-Performance InGaN-Based Green Resonant-Cavity Light-Emitting Diodes for Plastic Optical Fiber Applications

High-performance InGaN-based green resonant-cavity light-emitting diodes (RCLEDs) with a plating Cu substrate for plastic optical fiber communication applications are reported. Good stability of emission wavelength was obtained at 0.016 nm/mA . The RCLEDs presents low temperature dependence, showing only a 3% drop in light output power as the temperature increasing from 25 to 85degC. The superior performance can be attributed to the decreased dynamic series resistance and the enhanced thermal dissipation of the heat sink substrate.

Fabrication and characterization of the substrate-free InGaN-based resonant-cavity light-emitting diodes for plastic optical fiber communications

In this article, the authors report on the realization of substrate-free InGaN-based thin-film resonant-cavity light-emitting diodes (TF-RCLEDs). Experimentally, the sapphire substrate was stripped by using the laser lift-off technique. The λ∕4-thick Ta2O5∕SiO2 distributed Bragg reflector and the metallic Ag film with mirror reflectivities of 68% and 97% were, respectively, coated onto the top and bottom of the substrate-free LEDs to form a Fabry–Pérot cavity. The performances of LEDs are characterized by light output power, external quantum efficiency, emission spectrum, angular-resolved intensity distribution, and dynamic response. As a result, the fabricated TF-RCLEDs exhibit a low operating voltage of 3.34V at 20mA, a maximum light output power of 6.3mW at 140mA, and an external quantum efficiency of 5.5% at 4mA. In addition, the TF-RCLEDs show temperature insensitivity as compared to the normal LEDs directly grown on the sapphire substrates. Furthermore, the 50% viewing angle of TF-RCLED is smaller than that of normal LED, i.e., 146° versus 168° at 60mA. Finally, the eye pattern of the TF-RCLEDs is improved compared to that of the normal LEDs as operated at the data transmission rate of 100Mbit∕s. These results exhibit that the InGaN-based TF-RCLEDs are excellent candidates for the use in short-distance plastic optical fiber communications.

Linear Cascade GaN-Based Green Light-Emitting Diodes With Invariant High-Speed/Power Performance Under High-Temperature Operation

We demonstrate the performance of linear cascade green light-emitting diode (LED) arrays suited for use in plastic optical fiber (POF) communications in automobiles or harsh environments. With this three-LED array, driven by the constant voltage bias of an in-car battery output (12 V) we obtain high-speed ( ~ 100-Mb/s eye-opening), high-coupling power (0.9 mW), and a very small variation of coupled power versus temperature [- 0.12%degC-1 at room temperature (RT)] for the whole measured temperature range (i.e., RT to 120degC). Even under high bias current (100 mA) operation, our device can sustain a clear 150-Mb/s eye-opening from RT to 120degC. The static and dynamic measurement results indicate that the speed and power performance of this device are less sensitive to variations in ambient temperature than are those of the red resonant-cavity LEDs utilized for POF communication.

High-Speed GaN-Based Green Light-Emitting Diodes With Partially n-Doped Active Layers and Current-Confined Apertures

We demonstrate a high-speed GaN-based green light-emitting diode for plastic optical fiber (POF) communication applications. By using a combination of n-type doping and undoped In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> N/GaN based multiple quantum wells (MQWs), and a 76-mum-diameter current-confined aperture structure, we can obtain an extremely high electrical-to-optical (E-O) 3 dB bandwidth (~330 MHz), which is limited by the spontaneous recombination lifetime of the MQWs. A reasonable coupled power (-264 muW) can be simultaneously achieved for a 2 mm in diameter POF with a 0.5 numerical aperture (NA).