Seihyoung Lee

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.

Electromagnetically induced transparency based on guided-mode resonances

We present a novel, electromagnetically induced transparency system based on guided-mode resonances and numerically demonstrate its transmission characteristics through finite-difference time-domain simulations. The system is composed of two planar dielectric waveguides and a subwavelength grating. It is shown that by coupling the two resonant guide modes with a low- and high-quality factor, a narrow transparency window is generated inside a broad background transmission dip produced by the guided-mode resonance. Our work could provide another efficient way toward the realization of electromagnetically induced transparency.

Enhancement of the perceived image quality of a 2D/3D convertible directional-backlight unit system using a double-slit barrier array and an active diffuser

In this paper, a method to construct a directional-backlight unit system to separate the left-eye image and the right-eye image by adopting a double-slit barrier array is proposed to enhance the perceived quality of the realized 3D image. Additionally, the two-dimensional/three-dimensional convertible function is also realized by adopting an active diffuser to the spatial interlacing directional-backlight system.

Highly efficient, wavelength-selective out-coupling of cladding mode using tilted fiber grating and micro-etched cladding

A highly efficient, wavelength-selective detection through micro-etched groove on cladding of tilted fiber gratings (TFGs) is proposed and experimentally demonstrated. More than 88% power of the cladding mode is out-coupled into an optical power detector

Experimental and theoretical characterization of optical signal out-coupling through V-grooved optical fiber cladding

We demonstrate a highly efficient in-fiber out-coupling device. The core mode is coupled to the cladding by a tilted fiber Bragg grating and then the cladding mode is out-coupled from the optical fiber through V-grooved cladding. The light emitting characteristics are investigated experimentally and a maximum out-coupling efficiency of 54.8% is obtained.

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.

XG-PON1 OLT transceiver with a single-chip burst-mode receiver

We present the design and evaluation of a 10-gigabit small form factor pluggable transceiver with a prototype single-chip burst-mode receiver, a signal detection circuit, and a clock-data-recovery device for 2.5 Gbit/s upstream in the ITU-T G.987.2 recommendation.

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.

Single package directly modulated laser bidirectional optical subassembly using a modified mini-dual-in-line package for 10 Gbps passive optical networks

Abstract. A bidirectional optical subassembly comprised of a 2.5 Gbps distributed feedback (DFB) laser diode (LD) directly modulated laser transmitter and a 10 Gbps positive intrinsic negative photodiode receiver was developed for an optical network unit of a 10 Gbps passive optical network. Here, a low-cost mini-dual-in-line package was modified to contain whole components of a transmitter and receiver in a single space while satisfying the requirements of 10 Gbps micro-device package standards. The transmitter was fabricated to achieve high optical output power by placing a micro aspheric lens very close to the DFB LD and reducing the thermal resistance between an LD chip and heat sink to bring down the DFB LD chip temperature. As a result, the transmitter output power was 3.5 dB higher than a conventional transistor outline can BOSA due to a high optical coupling efficiency of more than 70% and a low thermal resistance for heat dissipation. The receiver sensitivity was −21  dBm at a bit error rate of 10−3 and the sensitivity penalty of the receiver due to signal crosstalk was less than 0.3 dB.

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.