Y. Kutuvantavida

Silicon-Organic Hybrid (SOH) and Plasmonic-Organic Hybrid (POH) Integration

Silicon photonics offers tremendous potential for inexpensive high-yield photonic-electronic integration. Besides conventional dielectric waveguides, plasmonic structures can also be efficiently realized on the silicon photonic platform, reducing device footprint by more than an order of magnitude. However, neither silicon nor metals exhibit appreciable second-order optical nonlinearities, thereby making efficient electro-optic modulators challenging to realize. These deficiencies can be overcome by the concepts of silicon-organic hybrid (SOH) and plasmonic-organic hybrid integration, which combine SOI waveguides and plasmonic nanostructures with organic electro-optic cladding materials.

100 Gbit/s OOK using a silicon-organic hybrid (SOH) modulator

We demonstrate a silicon-organic hybrid (SOH) Mach-Zehnder modulator suitable for 100 Gbit/s on-off keying (OOK) with peak-to-peak drive voltages of 1.4 V and energy consumption below 100 fJ/bit. Devices were fabricated using standard processes on a commercial silicon photonic platform.

Synthesis, Structural and Nonlinear Optical Properties of 2-(3-Cyano-4-{5-[1-(2-Hydroxyethyl)- 3,3-Dimethyl-1,3-Dihydro-Indol-2-ylidene]-Penta-1,3-dienyl}-5,5-Dimethyl-5H-Furan-2-ylidene)-Malononitrile

A chromophore for nonlinear optics with extended conjugation has been synthesized, and its structure determined from X-ray diffraction data. The compound crystallizes in the monoclinic system with the space group P21/n and Z = 4. The unit cell parameters are a = 10.7826(4) Å, b = 14.5943(5) Å, c = 15.3792(5) Å and beta = 96.213(2)°. A thin film containing 5% of the chromophore in amorphous polycarbonate when poled at 180°C and 60 V/μm yields a maximum r33 value of 206 pm/V. This is seven times higher than the value found for the archetypical inorganic material, lithium niobate.

Generation of 64 GBd 4ASK signals using a silicon-organic hybrid modulator at 80°C.

We demonstrate a silicon-organic hybrid (SOH) Mach-Zehnder modulator (MZM) generating four-level amplitude shift keying (4ASK) signals at symbol rates of up to 64 GBd both at room temperature and at an elevated temperature of 80°C. The measured line rate of 128 Gbit/s corresponds to the highest value demonstrated for silicon-based MZM so far. We report bit error ratios of 10-10 (64 GBd BPSK), 10-5 (36 GBd 4ASK), and 4 × 10-3 (64 GBd 4ASK) at room temperature. At 80 °C, the respective bit error ratios are 10-10, 10-4, and 1.3 × 10-2. The high-temperature experiments were performed in regular oxygen-rich ambient atmosphere.

Silicon-organic hybrid (SOH) modulators for intensity-modulation / direct-detection links with line rates of up to 120 Gbit/s

High-speed interconnects in data-center and campus-area networks crucially rely on efficient and technically simple transmission techniques that use intensity modulation and direct detection (IM/DD) to bridge distances of up to a few kilometers. This requires electro-optic modulators that combine low operation voltages with large modulation bandwidth and that can be operated at high symbol rates using integrated drive circuits. Here we explore the potential of silicon-organic hybrid (SOH) Mach-Zehnder modulators (MZM) for generating high-speed IM/DD signals at line rates of up to 120 Gbit/s. Using a SiGe BiCMOS signal-conditioning chip, we demonstrate that intensity-modulated duobinary (IDB) signaling allows to efficiently use the electrical bandwidth, thereby enabling line rates of up to 100 Gbit/s at bit error ratios (BER) of 8.5 × 10-5. This is the highest data rate achieved so far using a silicon-based MZM in combination with a dedicated signal-conditioning integrated circuit (IC). We further show four-level pulse-amplitude modulation (PAM4) at lines rates of up to 120 Gbit/s (BER = 3.2 × 10-3) using a high-speed arbitrary-waveform generator and a 0.5 mm long MZM. This is the highest data rate hitherto achieved with a sub-millimeter MZM on the silicon photonic platform.

Development of fibre Bragg grating based strain/temperature sensing system

We have characterised a strain and temperature sensing system being developed by Southern Photonics that uses a new Optical Interrogator and fibre Bragg gratings. We have determined the key strain and temperature coefficients, and shown that strain and temperature can be measured simultaneously. The experimental uncertainty is 5.2 pm when using the 1540 nm fibre Bragg grating, which corresponds to an experimental uncertainty in measuring the temperature of 0.54 ºC and in measuring the strain of 3.4 με. Simulations predict that a Bragg reflection of more than 90% can be achieved for Bragg Gratings in polymer thin films containing chromophores for grating lengths as small as 200 μm. A small Bragg grating length means that it should be possible to create waveguides and four Bragg gratings for strain tensor and temperature measurements within an area as small as 5×5 mm2.

Electrically modulated diffraction gratings in organic chromophore thin films

An electrically modulated diffraction grating has been demonstrated in poled polymer thin films containing the organic nonlinear optical chromophore, PYR-3 (2-{3-Cyano-4-[3-(1-decyl-1 H-pyridin-4-ylidene)-propenyl]-5,5-dimethy l-5 H-furan-2-ylidene}-malononitrile), and amorphous polycarbonate. A dc electric field induced change in the diffraction efficiency of up to 9% was observed. The diffraction efficiency modulation was likely due to an electric field induced change in the film thickness via a piezoelectric effect rather than via an electronic linear electro-optic effect.

High Electro-Optic Coefficient in Organic NLO Polymers: Poling and Study of the Relaxation Process

We report a high electo-optic coefficient (r33) of 175 pm/V in guest-host polymer films made by mixing amorphous polycarbonate with the chromophore, PYR-3 that was synthesized by our team. We have previously shown that PYR-3 has a large 2nd order nonlinear optical figure of merit. The measured r33 is five times larger than that of conventional inorganic materials such as lithium niobate. The decay of r33 with time has been studied for more than 1000 hours at room temperature and ambient atmosphere, and we find that the r33 value gradually reduced to a stable value of 34 pm/V after 40 days.

100 Gbit/s serial transmission using a silicon-organic hybrid (SOH) modulator and a duobinary driver IC

100 Gbit/s three-level (50 Gbit/s OOK) signals are generated using a silicon-organic hybrid modulator and a BiCMOS duobinary driver IC at a BER of 8.5×10⁻⁵(<10⁻²). We demonstrate dispersion-compensated transmission over 5 km.

Nanophotonic modulators and photodetectors using silicon photonic and plasmonic device concepts

Nanophotonic modulators and photodetectors are key building blocks for high-speed optical interconnects in datacom and telecom networks. Besides power efficiency and high electro-optic bandwidth, ultra-compact footprint and scalable co-integration with electronic circuitry are indispensable for highly scalable communication systems. In this paper, we give an overview on our recent progress in exploring nanophotonic modulators and photodetectors that combine the specific strengths of silicon photonic and plasmonic device concepts with hybrid integration approaches. Our work comprises electro-optic modulators that exploit silicon-organic hybrid (SOH) and plasmonic-organic hybrid (POH) integration to enable unprecedented energy efficiency and transmission speed, as well as waveguide-based plasmonic internal photo-emission detectors (PIPED) with record-high sensitivities and bandwidths.