Cormac Eason

Packaged hybrid III-V/silicon SOA

We present a hybrid III-V/silicon SOA, mounted in a planar package, with a fiber-to-fiber gain up to 10 dB, maximum internal gain of 28±2 dB, an internal noise figure of 10-11 dB and an output saturation power around 9 dBm.

Hybrid III-V/Silicon SOA in Optical Network Based on Advanced Modulation Formats

A hybrid III-V/silicon semiconductor optical amplifier (SOA) is presented, which shows a maximum fiber-to-fiber gain of 10 dB and a maximum internal gain around 28 ± 2 dB. The device was fabricated from III-V material wafer-bonded onto a silicon-on-insulator wafer. The optical mode transfers between silicon and III-V waveguides by means of waveguide tapers. Vertical grating couplers are used to connect the SOA to optical fibers. The device was packaged and tested in a transmission experiment. In a loop configuration containing 25 km of single-mode fiber, the SOA amplifies data signals of various modulation formats. Transmission with a bit error rate below the forward error correction limit is demonstrated for up to ten loops using QPSK, six loop using 8QAM, and four loops using 16QAM.

Optical and electronic packaging process for silicon photonic systems

Fibre optic interconnection processes and hybrid integration of electronic devices for high-speed Si photonic systems are presented. An overview of ePIXfab which offers affordable access to an advanced Si photonic foundry service is also presented.

The Influence of Thermistor Location on Temperature Measurement from a Photonic Package

This paper begins by describing some commonly used photonic packages. The requirements for optical connections to these packages are then discussed. Photonic packages are different to most electronic packages in that the thermal management requirements usually include maintaining the Photonic Integrated Circuit (PIC) at a fixed, sometimes below ambient, operating temperature rather than with keeping the temperature of a package below an upper limit as with most electronic packages. This means that an active Thermoelectric Module (TEM) based cooling system is required. A thermistor is fitted within the package to provide thermal feedback to the TEM controller. This paper uses finite element modelling to investigate whether there is a good match between the target temperature for the PIC and the temperature registered by the thermistor. The results of the modelling show that the model results are quite stable even with large variations in convection and thermistor thermal properties. The thermistor location influences the temperature measured from the package and its thermal response time, but follows the device temperature well enough to provide the TEM controller with adequate feedback to maintain the PIC at a steady temperature in steady state running conditions.

Optimization of PAM-4 transmitters based on lumped silicon photonic MZMs for high-speed short-reach optical links

We demonstrate how to optimize the performance of PAM-4 transmitters based on lumped Silicon Photonic Mach-Zehnder Modulators (MZMs) for short-reach optical links. Firstly, we analyze the trade-off that occurs between extinction ratio and modulation loss when driving an MZM with a voltage swing less than the MZMs Vπ. This is important when driver circuits are realized in deep submicron CMOS process nodes. Next, a driving scheme based upon a switched capacitor approach is proposed to maximize the achievable bandwidth of the combined lumped MZM and CMOS driver chip. This scheme allows the use of lumped MZM for high speed optical links with reduced RF driver power consumption compared to the conventional approach of driving MZMs (with transmission line based electrodes) with a power amplifier. This is critical for upcoming short-reach link standards such as 400Gb/s 802.3 Ethernet. The driver chip was fabricated using a 65nm CMOS technology and flip-chipped on top of the Silicon Photonic chip (fabricated using IMECs ISIPP25G technology) that contains the MZM. Open eyes with 4dB extinction ratio for a 36Gb/s (18Gbaud) PAM-4 signal are experimentally demonstrated. The electronic driver chip has a core area of only 0.11mm2 and consumes 236mW from 1.2V and 2.4V supply voltages. This corresponds to an energy efficiency of 6.55pJ/bit including Gray encoder and retiming, or 5.37pJ/bit for the driver circuit only.

Thermal challenges for packaging integrated photonic devices

In this work, we present thermal imaging and analysis of a silicon photonic optical network unit (ONU) for next generation passive optical networks (NG-PONs). A high-speed thermal camera is used to capture both the dynamic and steady-state temperatures of the photonic integrated circuit (PIC) and electric integrated circuit (EIC) at the core of the ONU. The dynamic temperature measurements of the PIC and EIC on powering-up the ONU show several distinct “steps” before the steady-state temperature is reached, and we show that these features can be predicted and fitted using a simple lumped-element rate-equation model. Steady-state temperature measurements made by mounting the ONU module on a thermally-stabilized stage allow the coefficient of performance (COP) of the thermoelectric cooler (TEC) in the module to be evaluated for simulated ambient temperatures ranging from 15-45 °C. This provides valuable information on the operational cost of the ONU in the field, where temperature-stabilization of the PIC represents a significant fraction of the overall power-budget.

Repeaterless data transmission at 1310 nm using silicon photonic integrated circuit

NRZ data with PRBS length 231 − 1, was propagated over 25 km of standard single mode fibre at a rate of 10 Gbit/s and 12.5 Gbit/s in a repeater-less transmission system. Results show that, for a received optical power of −13.2 dBm, the BER were 2.7 × 10−6 and 3.3 × 10−4 respectively, with sufficient margin below the FEC limit of 1 × 10−3 . The packaged transmitter comprised an integrated DFB laser, electro-absorption modulator and semiconductor optical amplifier hybrid integrated on silicon wafer.

1310 nm Data transmission using silicon photonic integrated circuit comprising directly modulated DFB laser and SOA

A directly modulated silicon photonic DFB laser integrated with a SOA was used to validate error-free transmission over 25 km of standard single mode fiber at 1310 nm. Data in NRZ format at a rate of 10 Gbit/s with PRBS of length 231−1 were used in the experiment.

25Gb/s Error-free transmission with a packaged chipset integrating a III-V/SOI DFB laser an electro-absorption modulator and a semiconductor optical amplifier

We report on the first hybrid III-V on silicon integration of a DFB laser, an electro-absorption modulator and a semiconductor optical amplifier. We packaged the fabricated chipset and validated the module through 25Gb/s error-free transmissions for short reach communication applications.

250-nm emitting LED optimized for optical fibre coupling

In this study we report the growth, fabrication and packaging of AlGaN-based light emitting diodes (LEDs) operating at 250 nm for space application [1]. The device fabrication and packaging processes were optimized to ensure a reliable optical fibre coupling. Electrical and optical characterization is presented and discussed; in particular a four-fold increase of the integrated ultraviolet power is demonstrated compared with a non-optimized device. A potential expansion of this approach to InAlN-based devices will also be discussed.