Jung Han Choi

Serial 100 Gb/s connectivity based on polymer photonics and InP-DHBT electronics.

We demonstrate the first integrated transmitter for serial 100 Gb/s NRZ-OOK modulation in datacom and telecom applications. The transmitter relies on the use of an electro-optic polymer modulator and the hybrid integration of an InP laser diode and InP-DHBT electronics with the polymer board. Evaluation is made at 80 and 100 Gb/s through eye-diagrams and BER measurements using a receiver module that integrates a pin-photodiode and an electrical 1:2 demultiplexer. Error-free performance is confirmed both at 80 and 100 Gb/s revealing the viability of the approach and the potential of the technology.

An ultracompact multimode interference wavelength splitter employing asymmetrical multi-section structures

By using the film mode matching method, a novel design for asymmetrical multi-section 1.55/1.31 μm wavelength splitter based on multimode interference has been proposed and simulated, which can be effectively applied to wavelength multiplexer, self-biased photodiode, and other optical devices. Compared with the conventional wavelength splitter design, the length of the novel structure has been reduced to at least 1/5, showing better performance. The presented structure is also adequate for splitting other wavelengths and more tolerable fabrications.

Multi-100 GbE and 400 GbE Interfaces for Intra-Data Center Networks Based on Arrayed Transceivers With Serial 100 Gb/s Operation

We demonstrate a 2 × 100 Gb/s transmitter and a 4 × 100 Gb/s receiver as the key components for multi-100-GbE and 400-GbE optical interfaces in future intradata center networks. Compared to other approaches, the two devices can provide significant advantages in terms of number of components, simplicity, footprint, and cost, as they are capable of serial operation with nonreturn-to-zero on-off keying format directly at 100 Gb/s. The transmitter is based on the monolithic integration of a multimode interference coupler with two Mach-Zehnder modulators on an electro-optic polymer chip, and the hybrid integration of this chip with an InP laser diode and two multiplexing and driving circuits. The receiver on the other hand is based on the hybrid integration of a quad array of InP photodiodes with two demultiplexing circuits. Combining the two devices, we evaluate their transmission performance over standard single-mode fibers without dispersion compensation and achieve a BER of 10-10 after 1000 m and a BER below 10-8 after 1625 m at 2 × 80 Gb/s, as well as a BER below 10-7 after 1000 m at 2 × 100 Gb/s. Future plans including the development of tunable 100 GbE interfaces for optical circuit-switched domains inside data center networks are also discussed.

\(2 \times 100\) -Gb/s NRZ-OOK Integrated Transmitter for Intradata Center Connectivity

We demonstrate an integrated transmitter that can generate two 100-Gb/s optical channels with simple nonreturn-to-zero-ON-OFF keying format. The transmitter is based on the combination of an ultrafast electro-optic polymer platform for the photonic integration and the optical modulation with ultrafast InP-double heterojunction bipolar transistor electronics for the multiplexing and the amplification of the 100-Gb/s driving signals. Through error-free transmission of 2 × 80-Gb/s signals over 1 km of SMF and transmission of 2 × 100-Gb/s signals over 500 m of single-mode fiber with error performance way below the forward error correction limit, we reveal the potential of the approach for parallel 100-GbE optical interfaces in small footprint transceivers for intradata center networks.

Tunable 100 Gbaud Transmitter Based on Hybrid Polymer-to-Polymer Integration for Flexible Optical Interconnects

We introduce a hybrid integration platform based on the combination of passive and electro-optic polymers. We analyze the optical and physical compatibility of these materials and describe the advantages that our hybrid platform is expected to have for the development of transmitters in terms of operation flexibility and speed. We combine our platform with InP electronics and develop a transmitter with 22-nm tunability in the C-band and potential for serial non-return-to-zero on-off-keying operation directly at 100 Gb/s. We investigate its transmission performance at 80 and 100 Gb/s using dispersion uncompensated standard single-mode fiber and demonstrate bit-error rate (BER) lower than 10-10 at 80 Gb/s after 1625 m, lower than 10-10 at 100 Gb/s after 500 m, lower than 10-9 at 100 Gb/s after 1000 m, and BER 10-7 at the same rate after 1625 m. We also employ the transmitter inside an experimental setup, which aims to emulate an optical circuit switched (OCS) domain of an intradata center network, and demonstrate at 100 Gb/s the way, in which its wavelength tunability can resolve contentions and improve the flexibility and the efficiency of the network. Finally, we outline our next plans, including the development of flexible and ultra-fast transmitters for coherent systems using the same polymer-to-polymer integration platform.

Impedance-engineered low power MZM / driver assembly for CFP4-size pluggable long haul and metro transceiver

A differential impedance-engineered 32 Gbit/s SiGe driver co-designed with an InP-based MZ-Modulator is demonstrated, showing record low 185 mW power consumption. The small footprint and low power is targeting towards CFP4-sized coherent transceivers. Results on IQ-Modulators will be presented.

Optimization of Photodiode Bandwidth Employing Peak Distortion Analysis

This paper addresses the systematic approach to optimize series inductance in the inductively peaked pin photodiode for high speed operation beyond 100 Gb/s. For this end, peak distortion analysis is introduced in addition to group delay dispersion technique. Through analytical analysis and comprehensive numerical simulations, inductance values are calculated to optimize vertical eye-opening and signal-to-noise ratio. For verification, an optical waveguide integrated pin photodiode with optimized inductance is fabricated and measured. Using the optical pulse measurement setup, its pulse response is measured, and a full-width at half maximum of 7.34 ps is obtained. The fabricated module is tested using 107 Gb/s return-to-zero signal and shows excellent eye-opening.

Passive and electro-optic polymer photonics and InP electronics integration

Hybrid photonic integration allows individual components to be developed at their best-suited material platforms without sacrificing the overall performance. In the past few years a polymer-enabled hybrid integration platform has been established, comprising 1) EO polymers for constructing low-complexity and low-cost Mach-Zehnder modulators (MZMs) with extremely high modulation bandwidth; 2) InP components for light sources, detectors, and high-speed electronics including MUX drivers and DEMUX circuits; 3) Ceramic (AIN) RF board that links the electronic signals within the package. On this platform, advanced optoelectronic modules have been demonstrated, including serial 100 Gb/s [1] and 2x100 Gb/s [2] optical transmitters, but also 400 Gb/s optoelectronic interfaces for intra-data center networks [3]. To expand the device functionalities to an unprecedented level and at the same time improve the integration compatibility with diversified active / passive photonic components, we have added a passive polymer-based photonic board (polyboard) as the 4th material system. This passive polyboard allows for low-cost fabrication of single-mode waveguide networks, enables fast and convenient integration of various thin-film elements (TFEs) to control the light polarization, and provides efficient thermo-optic elements (TOEs) for wavelength tuning, light amplitude regulation and light-path switching.

Low Power InP-Based Monolithic DFB-Laser IQ Modulator With SiGe Differential Driver for 32-GBd QPSK Modulation

We present for the first time 32 GBd QPSK of an InP-based IQ modulator with monolithically integrated laser and co-packaged SiGe driver. Power consumption is 1.1 W, which is well within the CFP4 module overall budget of 6 W.

Electro-Optical Co-Design to Minimize Power Consumption of a 32 GBd Optical IQ-Transmitter Using InP MZ-Modulators

This paper addresses the power reduction concepts of an electro-optical transmitter applicable for future small form factor modules such as CFP4. To satisfy the power restrictions of these standards, equations and detailed explanations of the relevant shares of overall power consumption are given. To improve the overall efficiency, an open collector driver realized in a SiGe technology with fT = 190 GHz and fmax = 200 GHz is proposed for driving an InP-based IQ MZ-modulator. This approach saves 30 % of the driver power and achieves an EVMrms of 8.7 % for a QPSK-Signal at 32 GBd. A detailed performance comparison to a structurally identical back terminated driver is presented. Further power reduction is demonstrated with a bias tee configuration for a single modulator. DPSK measurements show a very low power consumption of 290 mW at an EVMrms of 7.5 %. The presented bias tee solution simplifies the assembly without performance compromises. All drivers presented in this paper have differential input/output signals and were designed for a non 50 Ohm output impedance to optimize power consumption and performance.