Shiyun Lin

Error-free operation of a polarization-insensitive 4λ x 25 Gbps silicon photonic WDM receiver with closed-loop thermal stabilization of Si microrings

We report the first closed-loop operation of a 100 Gbps polarization-insensitive, 4-channel wavelength-tracking WDM receiver in silicon photonics platform. Error-free operation is achieved with input polarization scrambling over input wavelength change of 4.5 nm using efficient thermal tuning of Si microring demux, corresponding to greater than 60°C fluctuation in temperature.

III-V/Si Hybrid Laser Arrays Using Back End of the Line (BEOL) Integration

Creating arrays of efficient optical sources to enable dense integration of silicon photonic transceivers with silicon very large-scale integration circuits remains a challenge. We review manufacturing strategies and challenges for back-end-of-line integration of tunable, external-cavity lasers using edge-coupled and surface-normal-coupled integration approaches showing that such laser arrays can be manufactured with a fab-less model. We demonstrate, for the first time, hybrid laser arrays using both integration approaches highlighting performance and design differences. We also discuss challenges and opportunities for each method and present experimental techniques to reduce alignment tolerance and improve laser stability and mode control.

Modulation of Coherently Coupled Phased Photonic Crystal Vertical Cavity Laser Arrays

The modulation properties of two-element photonic crystal ion-implanted coherently coupled vertical cavity surface emitting laser arrays emitting at 850 nm are reported. Single mode emission into either the in-phase or out-of-phase supermode and significant modulation bandwidth enhancement are obtained for both operating conditions. We model our device as a monolithically integrated, mutually optically injection-locked laser system and show that the phase detuning and injection ratio between array elements are critical parameters influencing modulation bandwidth. Comparison of our experimental measurements to our model is consistent with mutual injection locking. Modulation bandwidth greater than 30 GHz and up to 37 GHz is consistently found for several array designs. We show the modulation response can be tailored for different applications.

A Process-Tolerant Ring Modulator Based on Multi-Mode Waveguides

We present a novel 3.3-μm radius ring modulator design with dramatically reduced resonance wavelength variations. By implementing a multi-mode waveguide design for the ring waveguides, phase errors from processing non-idealities in waveguide width and etching depth are significantly reduced. Measured resonance wavelengths from four 200-mm wafers fabricated in a commercial 130-nm CMOS foundry showed a total of ~5-nm peak-to-peak variation, which is only about 1/6 of the free spectral range of the ring design. With this tighter control over the absolute resonance positions, the tuning range and tuning power requirements of the ring modulators can be significantly reduced, which in turn enhances their functionality for applications in high density, energy-efficient high-performance computing systems.

A CMOS-compatible low back reflection grating coupler for on-chip laser sources integration

We demonstrate a low back reflection grating coupler on a SOI CMOS-compatible process designed for vertical integration of on-chip laser sources. It showed <;-26dB back reflection and 1.9dB coupling loss to a 4μm-diameter laser mode.

III–V/Si Vernier-Ring Comb Lasers (VRCLs)

We present a novel reconfigurable comb laser design that enables channel sparing, and demonstrate its functionality in a III-V/Si external cavity configuration. The laser is comprised of a single shared tunable Si ring mirror Vernier-paired with an array of tunable channel ring filters each coupled to their respective reflective semiconductor optical amplifier. This comb laser is not only tunable, capable of shifting all comb lines together, but it is flexible, able to change the spacing of channels in the comb within a fixed grid defined by the ring mirror. This flexibility results in features not previously demonstrated in a comb, such as mixed channel spacing and channel sparing capability. This is a practical candidate for flexible, scalable wavelength division multiplexed links targeting the next generation of data centers for the cloud.

Si/III-V hybrid external-cavity laser stabilization using real-time micro-ring monitoring and feedback control

Stable mode-hop-free operation for a Si/III-V hybrid external-cavity laser was demonstrated during 320mA bias current sweep using a real-time ring monitoring, a fast feedback control loop, and a simple bang-bang control algorithm, by both tunable micro-ring filter and cavity phase section.

Manufacturable hybrid silicon array laser source using an interposer based back-end-of-the-line integration

We report a silicon interposer based 1×4 external-cavity hybrid III-V/Si laser array using a manufacturable back-end-of-the-line integration. All channels are individually-tunable and wavelength-stabilized with a threshold current of 14mA, output powers of >3mW, over 35dB side mode suppression ratio and less then 46kHz linewidth.

III-V/Si Hybrid Laser Stabilization Using Micro-Ring Feedback Control

We present a real-time approach for stabilizing a III-V/Si hybrid external-cavity laser implemented using microring monitoring and a feedback control loop. Laser mode stabilization over bias current and stage temperature variations are experimentally demonstrated. We achieved single-mode and mode-hop-free laser operation as the bias current was swept across 320 mA. The same feedback control also enabled wavelength-locked laser operation using an intracavity phase control. The feedback control was also applied to an integrated on-chip hybrid laser, and mode-hop-free laser operation was demonstrated over 23 °C substrate temperature variation.