Kwon-Seob Lim

A Novel Low-Cost Fiber In-Line-Type Bidirectional Optical Subassembly

A novel low-cost fiber in-line-type bidirectional optical subassembly using a tilted fiber Bragg grating has been developed for fiber-to-the-home applications. We successfully realized a low-cost subassembly by reducing the number of components and simplifying the packaging process. The extinction ratio of 14.8 dB, receiver minimum sensitivity of -26.5 dBm at a bit-error rate of 10-12 and frequency response of 2.7 GHz were experimentally obtained. The electrical crosstalk between transmitter and receiver part was less than -86 dB up to 2.5 GHz.

Low-cost 1×2 plastic optical beam splitter using a V-type angle polymer waveguide for the automotive network

The design, fabrication, and characteristic of the plastic optical fiber (POF), beam splitter, for the automotive network, has been demonstrated. The fabricated 1×2 POF beam splitter consisted of a poly(methylmethacrylate) (PMMA) core, which had a structure of circular waveguide and a diameter of 0.98 mm, UV curable epoxy (PC-414) clading of 0.02 mm thickness, and three POF pigtails with multimedia oriented system transport standard ferrules. A 1×2 PMMA waveguide, which was designed to have an optimal angle of 15.8 deg at the beam splitting point, was fabricated using the injection molding method for mass production. The total volume of the fabricated 1×2 POF beam splitter is 48×18×12 mm3 with 1.2 m length input and output POF pigtails. From the measurement results, we experimentally confirm that the fabricated 1×2 POF beam splitter has excellent properties such as a beam splitting ratio of 50:50 ± 10 % and excess loss of less than 3.52 dB and it works well up to 250 Mbps for the automotive network.

1/10 Gb/s single transistor-outline-CAN bidirectional optical subassembly for a passive optical network

Abstract. We propose a novel, low-cost bidirectional optical subassembly (BOSA) that uses a single glass-sealed conventional transistor-outline (TO)-CAN package for passive optical network application. In this BOSA, optical transmitting and receiving functions are incorporated into a silicon optical bench and in a TO-CAN package, respectively. With these features, the optical and electrical crosstalk is efficiently suppressed. The single TO-CAN BOSA has an extinction ratio of 11.69 dB and output power of 2.93 dBm for 1.25  Gb/s operation. The penalty of optical dispersion is 1.2 dB after 20-km single-mode fiber transmission. The receiver sensitivity is less than −30  dBm at a bit error rate of 10−3 for 10.3  Gb/s operation and the signal crosstalk penalty of a single TO-CAN BOSA is 0.8 dB.

Compact bidirectional optical subassembly vertically stacked with 1.25-Gbps transmitter and 10-Gbps receiver for passive optical networks

A compact bidirectional optical subassembly (BOSA) for a 1.25/10-Gbps passive optical network is developed. A vertically stacked 1.25-Gbps transmitter based on a silicon optical bench, and a 10-Gbps receiver based on a low temperature cofired ceramic are implemented to realize low-cost manufacturing and miniaturization for single package application. The proposed BOSA delivers an extinction ratio more than 10 dB at 1.25-Gbps modulation, optical output coupling efficiency is more than 60%, rise and fall time is under 300 ps, and the side mode suppression ratio is more than 35 dB for the transmitter part. For the receiver part, responsivity is more than 0.6 A/W, and sensitivity is lower than -17 dBm at a 10-Gbps bit error rate 10-12 and -21 dBm at BER 10-3 without forward error correction. The cross talk between receiver and transmitter is less than -53 dB up to 10 GHz, and optical isolation is 33 dB.

10-Gbps electroabsorptive modulated laser bidirectional optical subassembly using novel two-window flat package for passive optical network

A novel 10-Gbps bidirectional optical subassembly (BOSA) comprised of a 1577 nm electroabsorptive modulated laser (EML) transmitter optical subassembly (TOSA) and 1270 nm avalanche photodiode (APD) receiver optical subassembly (ROSA) was developed. Here, a 10-Gbps microdevice compatible two-window flat package was proposed to simplify the EML BOSA structure, considering both the mechanical reliability and cooling performance. As a result, an optical output power of 8 dBm was obtained due to a high optical coupling efficiency of 60%, an extinction ratio of 7 dB, and a dispersion penalty at 20 km transmission of less than 1.5 dB for the EML TOSA. The APD ROSA sensitivity was -21.5 dBm at a bit error rate (BER) of 10−12 and -27 dBm at a BER of 10−3 without forward error correction. In addition, the sensitivity penalty of the APD ROSA due to signal crosstalk was less than 1.2 dB.

Fully passive-alignment pluggable compact parallel optical interconnection modules based on a direct-butt-coupling structure for fiber-optic applications

Abstract. A low-cost packaging method utilizing a fully passive optical alignment and surface-mounting method is demonstrated for pluggable compact and slim multichannel optical interconnection modules using a VCSEL/PIN-PD chip array. The modules are based on a nonplanar bent right-angle electrical signal path on a silicon platform and direct-butt-optical coupling without a bulky and expensive microlens array. The measured optical direct-butt-coupling efficiencies of each channel without any bulky optics are as high as 33% and 95% for the transmitter and receiver, respectively. Excellent lateral optical alignment tolerance of larger than 60  μm for both the transmitter and receiver module significantly reduces the manufacturing and material costs as well as the packaging time. The clear eye diagrams, extinction ratios higher than 8 dB at 10.3 Gbps for the transmitter module, and receiver sensitivity of better than −13.1  dBm at 10.3 Gbps and a bit error rate of 10−12 for all channels are demonstrated. Considering that the optical output power of the transmitter is greater than 0 dBm, the module has a sufficient power margin of about 13 dB for 10.3 Gbps operations for all channels.

A novel packaging method of fully passive optical alignment for multi-chennel optical interconnection module

In this paper, a novel packaging method of fully passive optical alignment and surface mounting for parallel optical interconnects modules has been developed for a high-capacity data transmission such as chip-to-chip and board-to-board interconnects within smart device and interconnects between devices.

Low-cost dual-wavelength optical subassembly for fiber optic applications

A dual-wavelength optical subassembly (OSA) using a typical glass-sealed transistor outline-can (TO-CAN) package is presented. The proposed OSA has a simple structure and is sufficiently compact to integrate two optical channels in a single TO-CAN package. And the proposed OSA realizes the reduction in cost by reducing the number of parts and the laser welding process. The measurement results of 3 dB of bandwidth of the proposed dual-wavelength OSA are more than 4.5 GHz for transmitter module and more than 4.0 GHz for receiver module. The clear eye diagrams with more than 8.6 dB of the extinction ratio and less than −24.5  dBm of receiver minimum sensitivity at a bit error rate of 10−10 are obtained under 2.5  Gbit/s operations.

Novel bidirectional optical subassembly with embedded filter, 45-degree angle polished fiber cladding and etched fiber core

We propose and demonstrate a novel approach to identify linear and nonlinear propagation regimes of an optical signal in an optical fiber link by using chaos analysis. We show that the chaotic characteristics of a propagating optical signal are affected by both the chromatic dispersion and the nonlinear effects in the optical fiber. Linear or nonlinear behavior is detected by determining the maximum Lyapunov exponent of the signal and the use of the recurrence plot technique. An experimental demonstration is performed using 10-Gbps signal propagation in a 100-km fiber link with different launched optical powers. Chaos analysis shows a clear identification of the linear and nonlinear optical propagation regimes by using a classification scheme based on a multilayer neural network. Numerical simulations confirm the experimental results.

Simultaneous transmission of 2.5-Gb∕s baseband and 5.8-GHz-band radio frequency signals on a single wavelength using optical diplexer and mixed-signal multiplexer

Simultaneous transmission of 2.5-Gb/s baseband and 5.8-GHz-band radio frequency (RF) signals on a single wavelength via a fiber link is successfully demonstrated using the optical diplexer and the newly designed novel baseband/RF mixed-signal multiplexer (MUX) with no mixer. The bit error rate (BER) <10−12 of the baseband signal is maintained when the RF input power is less than −14 dBm after 10-km-long distance transmission. The maximum carrier-to-noise ratio (CNR) of the RF signal is measured as 23 dB with no additional amplifier. The measured insertion loss for the RF signal of the mixed-signal MUX is 1.2 dB at 5.8 GHz, and the isolations between the two bands are about 20 dB for the baseband and 30 dB for the RF band, respectively.