Electrically controlled 1 × 2 tunable switch using a phase change material embedded silicon microring.

Phase change material Ge2Sb2Te5 (GST) has recently emerged as a highly promising candidate for photonic device applications owing to its high optical contrast, self-holding bi-stability, and fast material response. Here, we propose and analyze a 1×2 tunable switch using a GST embedded silicon microring resonator exploiting high optical contrast during GST phase change and a high thermo-optic coefficient of amorphous phase GST. Our device exhibits high extinction ratios of 25.57 dB and 18.75 dB at through and drop ports, respectively, with just a 1 µm long GST layer. The two states of the switch are realizable by electrically inducing phase change in GST. For post phase change from amorphous to crystalline and vice versa, the fall time down the 80% of phase transition temperature is ∼66ns and ∼45ns, respectively. The resonance wavelength shift per unit active length is 0.661 nm/µm, and the tuning efficiency is 1.16 nm/mW. The large wavelength tunability (4.63 nm) of the proposed switch makes it an attractive option for reconfigurable photonic integrated circuits.

High-resolution notch filters and diplexers based on SU-8 inverted rib waveguides.

We performed an end-to-end process, ranging from design, fabrication, and characterization of integrated polymeric optical devices under a mass production technology. Inverted rib waveguides formed by SU-8 photoresist deposited on top of full wafers, with trenches in silica, were used as a platform to implement such optical devices. Narrowband spectral filters based on microracetrack resonators and diplexers based on directional couplers, both with high extinction ratios, are demonstrated. Full wafers of those devices were processed in a complementary metal-oxide-semiconductor foundry's 150 mm-facility. We believe the results are promising for applications ranging from telecommunication components to sensing devices.

Reconfigurable silicon thermo-optical ring resonator switch based on Vernier effect control.

A proof-of-concept for a new and entirely CMOS compatible thermo-optic reconfigurable switch based on a coupled ring resonator structure is experimentally demonstrated in this paper. Preliminary results show that a single optical device is capable of combining several functionalities, such as tunable filtering, non-blocking switching and reconfigurability, in a single device with compact footprint (~50 µm x 30 µm).

Minimizing the number of voltage sources for pinched injection on a microfluidic device.

This work presents a novel injection design for microfluidic systems which is able to perform pinched injections using a single power supply. This geometry also minimizes the injection time compared to standard pinched injections. This new design was developed and investigated by computer simulation and these results were confirmed by experimental studies using the injection of fluorescent dye.

On-chip silicon photonic wavelength control of optical fiber lasers.

Tunable silicon microring filters are used to demonstrate CMOS-compatible on-chip wavelength control of Er(+) doped fiber-lasers. An onchip Ni-Cr micro-heater consuming up to 20 mW is capable of tuning the Si microring filter by 1.3 nm with a lasing linewidths narrower than 0.02 nm. This approach enables arbitrary multiple wavelength generation on a silicon chip. Possible applications include on-chip and chip-to-chip dense-wavelength division multiplexed communications and sensor interrogation.

Experimental demonstration of a wafer-level flexible probe for optical waveguide testing.

A flexible optical probe that accomplishes wafer-level directional coupling of light into optical waveguides is investigated theoretically and experimentally. Simulated results indicate high coupling efficiencies in excess of 80% for a range of parameters. Probe fabrication was implemented using SU8 as flexible waveguide material. Coupling of light from flexible probe to an S-shaped test waveguide demonstrated 11% efficiency compared to direct butt coupling. These results may lead to increased yield, shorter development cycles and overall savings in PLC packaging costs.

All-optical control of light on a silicon chip.

Photonic circuits, in which beams of light redirect the flow of other beams of light, are a long-standing goal for developing highly integrated optical communication components. Furthermore, it is highly desirable to use silicon--the dominant material in the microelectronic industry--as the platform for such circuits. Photonic structures that bend, split, couple and filter light have recently been demonstrated in silicon, but the flow of light in these structures is predetermined and cannot be readily modulated during operation. All-optical switches and modulators have been demonstrated with III-V compound semiconductors, but achieving the same in silicon is challenging owing to its relatively weak nonlinear optical properties. Indeed, all-optical switching in silicon has only been achieved by using extremely high powers in large or non-planar structures, where the modulated light is propagating out-of-plane. Such high powers, large dimensions and non-planar geometries are inappropriate for effective on-chip integration. Here we present the experimental demonstration of fast all-optical switching on silicon using highly light-confining structures to enhance the sensitivity of light to small changes in refractive index. The transmission of the structure can be modulated by up to 94% in less than 500 ps using light pulses with energies as low as 25 pJ. These results confirm the recent theoretical prediction of efficient optical switching in silicon using resonant structures.

Experimental demonstration of guiding and confining light in nanometer-size low-refractive-index material.

We experimentally demonstrate a novel silicon waveguide structure for guiding and confining light in nanometer-wide low-refractive-index material. The optical field in the low-index material is enhanced because of the discontinuity of the electric field at high-index-contrast interfaces. We measure a 30% reduction of the effective index of light propagating in the novel structure due to the presence of the nanometer-wide low-index region, evidencing the guiding and confinement of light in the low-index material. We fabricate ring resonators based on the structure and show that the structure can be implemented in highly integrated photonics.

All-optical switching on a silicon chip.

We present an experimental demonstration of fast all-optical switching on a silicon photonic integrated device by employing a strong light-confinement structure to enhance sensitivity to small changes in the refractive index. By use of a control light pulse with energy as low as 40 pJ, the optical transmission of the structure is modulated by more than 97% with a time response of 450 ps.

Nanotaper for compact mode conversion.

We propose and demonstrate an efficient coupler for compact mode conversion between a fiber and a submicrometer waveguide. The coupler is composed of high-index-contrast materials and is based on a short taper with a nanometer-sized tip. We show that the micrometer-long silicon-on-insulator-based nanotaper coupler is able to efficiently convert both the mode field profile and the effective index, with a total length as short as 40 microm. We measure an enhancement of the coupling efficiency between an optical fiber and a waveguide by 1 order of magnitude due to the coupler.