Yun-Kyung Oh

Bragg grating-assisted WDM filter for integrated optical triplexer transceivers

We designed and experimentally demonstrated a Bragg grating-assisted wavelength-division-multiplexing filter for the three-wavelength multiplexing on a planar-lightwave-circuit platform. The 1310- and 1550-nm lights were designed to be separated after passing the directional coupler by a half-cycle and a full-cycle coupling actions with losses of 0.07 and 0.19 dB, respectively. The 1492-nm light was reflected back by a Bragg grating fabricated on the directional coupler and its loss was less than 2.0 dB. We also introduced and discussed the new concept of an integrated optical triplexer transceiver using this filter.

Thin film filter-embedded triplexing-filters based on directional couplers for FTTH networks

We designed and experimentally demonstrated a thin film filter (TFF)-embedded directional coupler-type triplexing-filter on the planar-lightwave-circuit platform. The triple-play multiplexing was significantly simplified by using one TFF. The 1.31- and 1.55-/spl mu/m lights were designed to be divided after passing the directional coupler by half-cycle and full-cycle coupling actions, respectively. The 1.49-/spl mu/m light was reflected by a TFF inserted in a trench on the directional coupler. The insertion losses of fabricated triplexing-filters were less than 2.0 dB with bandwidths of 20 nm. The newly proposed triplexing-filter provides a cost-effective high-performance solution for fiber-to-the-home networks.

AC-coupled burst-mode OLT SFP transceiver for gigabit ethernet PON systems

This letter presents a burst-mode optical line terminal transceiver for a gigabit ethernet passive optical network system. The transceiver package is compliant with small form-factor pluggable multisource agreement. The burst-mode receiver employs an ac-coupling between commercial transimpedance amplifier and limiting amplifier. The burst-mode receiver achieves sensitivity of -24.4 dBm at bit-error ratio 10/sup -12/ with pseudorandom bit sequence 2/sup 7/-1 data, overload of -1.5 dBm, and system dynamic range of 22.9 dB for preamble of 512 bits and guard time of 32 bits. Burst-mode penalty of 1.6 dB is also observed by experiment.

Triple Wavelength Demultiplexers for Low-Cost Optical Triplexer Transceivers

We report triple wavelength demultiplexers adopting a thin-film filter (TFF) and a waveguide Bragg grating as a reflector for low-cost integrated optical triplexer transceivers deployed for the triple play service-based fiber-to-the-home (FTTH) networks. In the proposed demultiplexers, 1310- and 1550-nm lights were designed to be divided after passing the planar lightwave circuit-based directional coupler by half-cycle and full-cycle coupling actions, respectively. The 1490-nm light was reflected by a TFF or Bragg grating. The losses of the demultiplexers were less than 2.0 dB at all ports. The average crosstalk among the three lights for the demultiplexers was about -20 dB or better. Through a single reflector, the demultiplexer structures are significantly simplified, and cost is reduced. The proposed triple wavelength demultiplexers provide cost-effective and high-performance solutions for FTTH network systems

Reduction of insertion loss of thin film filters embedded in PLC platforms

We propose and experimentally demonstrate a method of reducing insertion loss of a thin-film-filter-embedded planar-lightwave-circuit platform for a triplexer transceiver module. Significant loss reduction was achieved by adding horn waveguide elements at the interfaces between the thin film filter and the output-port (transmission and reflection) waveguides.

A Novel Hybrid WDM/SCM-PON using Reflective Semiconductor Optical Amplifier

A hybrid wavelength-division-multiplexed/sub-carrier-multiplexed passive optical network having the same wavelength both upstream and downstream is presented by using a reflective semiconductor optical amplifiers (RSOA) as a modulator. We investigated the down stream of 622.08Mbps using a DFB-LD with direct modulation and the 100Mbps upstream using a RSOA as a modulator with 900MHz SCM signal. In our scheme, a novel efficient and cost effective WDM/SCM-PON using same wavelength for down/up stream at each ONU proposed and demonstrated by BER measurements.

Circularly Polarized External Cavity Laser Hybrid Integrated With a Polyimide Quarter-Wave Plate on Planar Lightwave Circuit

We propose and demonstrate a circularly polarized external cavity laser (ECL) hybrid integrated on a planar lightwave circuit (PLC). The ECL is composed of a spot-size converter integrated laser diode, a UV-written grating, and a polyimide quarter-wave plate on the PLC using hybrid-integration technology. The polyimide quarter-wave plate of an 8.8-mum thickness was inserted in a trench with a 20-mum width and a 300-mum depth on the PLC platform, and fixed with a UV-curable adhesive. The ECL hybrid integrated with the polyimide wave plate becomes highly circular-polarized with a degree of circular polarization of 0.992. This circularly polarized ECL operated with a sidemode suppression ratio of >50 dB at ~1550 nm.

Embodiment of optical interconnection circuits for the mobile phone application

This paper intends to show that the optical interconnection can be a substitute of the electrical serial interface in mobile application. We designed the optical interconnection interface circuits on the evaluation boards which typically correspond to the mobile phone and transferred the data through the optical waveguide module. There are 4 pairs of VCSEL (Vertical Cavity Surface Emitting Laser) and PD (Photo Diode) arrays in the waveguide module and they are used to send the strobe and the data signal in dual-simplex (i.e. Two Directions with Unidirectional Lanes) configuration. We have demonstrated a successful data transmission of moving picture and real-time camera module images to the main-LCD (Liquid Crystal Display) repeatedly and the still pictures to the sub-LCD at the maximum speed of 400Mbps.

Waveguide design and fabrication of trench for hybrid integrated optic devices

The hybrid integration of passive and optoelectronic devices has been widely researched. One of the main applications of this technique is for the fiber to the home (FTTH) network. In bi-directional transceivers, integrated WDM filters have been used to separate or combine the optical signals. Thin film filter (TFF) embedded waveguide type is effective for an application requiring wide bandwidth and low loss. Although the insertion loss of TFF itself is quite low, significant loss occurs at the trench and it depends on the geometrical structure and fabrication errors of the trench waveguide. The conventional sawing method and deep reactive ion etching technique were used for trench fabrication. In the case of using DRIE process, fabrication error was reduced and position error of the trench was controlled within 1um. This method could also enhance the platform design flexibility. To reduce the coupling loss between input and reflection waveguides with high tolerance of filter position, a few mode waveguide and horn waveguide were proposed. The insertion losses of transmission and reflection were less than 0.5dB and 0.7dB respectively. The 1dB tolerance of filter position was improved to be nearly twice than that of the conventional waveguide.

High-power wide temperature range (-40°C ~100°C) operation of 1300-nm InGaAsP DFB lasers with asymmetric MQWs

We demonstrate 1.25 Gbps 1300 nm InGaAsP/InP DFB lasers employing asymmetric MQWs structures operable over a wide temperature range of -40°C to 100°C, which has an optical power of 10 mW and a side mode suppression ratio (SMSR)and a Fabry-Perot suppression ratio (FPSR) of >30dB.