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We demonstrate high-speed modulations in dual-polarization (DP) quadrature phase shift keying and DP 16- and 32-quadrature amplitude modulation formats with radio frequency driving voltage as low as 2 V ppd using a packaged monolithic silicon DP in-phase quadrature modulator that employs a highly efficient vertical p-n junction rib-waveguide phase shifter.

Silicon photonics circuits are playing more and more important role in optical communication and interconnect fields [1, 2]. Many silicon CMOS technique compatible photonics integrated devices are reported [3, 4]. Most of those silicon components are based on optical waveguide. But conventional integrated optical waveguide is without memory feature. One hand, which makes us in trying to change the refractive index of the optical waveguide, must continually support energy to maintain the state of the waveguide, such as optical switch and modulators. And other hands, memory functional PIC into computer memory system, will solve van Neumann bottleneck issue.

In this paper, we have designed, fabricated and characterized silicon nitride grating couplers with high efficiency at 1490 nm. The devices are fabricated using deep UV photolithography with resolution requirement of ∼500 nm. The grating coupler fabricated yields a peak coupling efficiency of −5.1 dB. The 1-dB bandwidth of the grating coupler is 60 nm.

We propose CMOS-compatible multi-layered waveguide system for silicon hybrid integration. Numerical simulation of vertical light coupling between different layers, and fabrication of dual-layered waveguide devices for multiple die-to-wafer bonding are performed, suggesting the integration feasibility.

We demonstrated a low loss silicon suspended coupler for coupling to DFB laser diode with wide tolerance. The measured insertion loss is ∼3.5 dB. The alignment tolerance is >±0.7 µm for 1 dB excess loss.

A 3D silicon photonics packaging architecture based on a Cu-metallized Si-photonics through-silicon-via (TSV) interposer has been designed and experimentally demonstrated, which achieves flexible and compact electro-optical integration of different functionalities for high density on-board optics module. 3D photonics architecture for on-package integration overcomes the difficulties in sophisticated co-integration electronic design automation (EDA) tool and processing skills of monolithic integration. This photonic TSV interposer consists of monolithically integrated TSV, tunable arrayed waveguide grating (AWG), optical (Mach-Zehnder Interferometer) modulators and germanium photodetectors (PD). The fabrication process of this 3D photonics architecture is presented. 800 GHz channel tunability is achieved by the tunable AWG, and 20 GHz-bandwidth and 28 GHz-bandwidth is achieved by the silicon modulator and germanium PD on this on-package TSV integration module, respectively. This 3D photonics module realizes a 30 Gbps-data rate. This work has established the toolboxes of 3D silicon photonics packaging based on TSV interposer for high density on-board optics module.

This paper focuses on latest progress in experimental and theoretical studies on silicon-based carrier-depletion PNjunction phase shifters in terms of high modulation efficiency for energy-efficient photonic networks of high transmission capacity. Modulation efficiency of rib-waveguide phase shifters having various PN-junction configuration are characterized with respect to DC figure of merit defined for phase shifters using carrier-plasma dispersion as the physical principle of refractive-index modulation. In addition, RF drive voltage required for 10-Gb/s on-off keying is characterized for rib-waveguide phase shifters including lateral and vertical PN-junction configurations.

Despite all the eminent advantages of silicon photonics, other materials need to be integrated to fulfill the functions that are difficult to realize with silicon alone. This is because silicon has a low light emission efficiency and a low electro-optic coefficient, limiting the use of silicon as a material for light sources and modulators. A strong two-photon absorption (TPA) at high intensities also limits the use of silicon in applications exploiting nonlinear effects. In addition, signal amplification is needed to compensate the insertion and propagation losses in silicon nanowaveguides. To address these issues we have demonstrated the integration of atomic layer deposited nanolaminates on silicon waveguides. Firstly we demonstrate slot waveguide ring resonators patterned on a silicon-on-insulator (SOI) wafer coated with an atomic layer deposited organic/inorganic nanolaminate structure, which consists of alternating layers of tantalum pentoxide (Ta2O5) and polyimide (PI) [1]. These materials were selected since the ALD process for depositing Ta2O5/PI nanolaminate films is already available [2] and both materials exhibit high third order nonlinearities [3-4]. In our nanolaminate ring resonators, the optical power is not only confined in the narrow central air slot but also in several parallel sub-10 nm wide vertical polyimide slots. This indicates that the mode profiles in the silicon slot waveguide can be accurately tuned by the atomic layer deposition (ALD) method. Our results show that ALD of organic and inorganic materials can be combined with conventional silicon waveguide fabrication techniques to create slot waveguide ring resonators with varying mode profiles. Secondly we demonstrate the integration of atomic layer deposited erbium-doped aluminum oxide (Al2O3) nanolaminates on silicon waveguides. This method provides an efficient way for controlling the concentration and distribution of erbium ions. We have applied this method on silicon strip and slot waveguides and show signal enhancement. Our results show that atomic layer deposited nanolaminates can potentially open new possibilities for various photonic applications, such as silicon photonic devices for light emission and amplification, optical sensing and all-optical signal processing. References [1] A. Autere, L. Karvonen, A. Saynatjoki, M. Roussey, E. Farm, M. Kemell, X. Tu, T.Y. Liow, G.Q. Lo, M. Ritala, M. Leskela, S. Honkanen, H. Lipsanen, and Z. Sun, "Slot waveguide ring resonators coated by an atomic layer deposited organic/inorganic nanolaminate," Opt. Express 23, 26940-26951 (2015) [2] L. D. Salmi, E. Puukilainen, M. Vehkamaki, M. Heikkila, and M. Ritala, “Atomic layer deposition of Ta2O5/polyimide nanolaminates,” Chem. Vap. Deposition 15, 221–226 (2009). [3] S. Morino, T. Yamashita, K. Horie, T. Wada, and H. Sasabe, “Third-order nonlinear optical properties of aromatic polyisoimides,” React. Funct. Polym. 44, 183–188 (2000). [4] C.-Y. Tai, J. Wilkinson, N. Perney, M. Netti, F. Cattaneo, C. Finlayson, and J. Baumberg, “Determination of nonlinear refractive index in a Ta2O5 rib waveguide using self-phase modulation,” Opt. Express 12, 5110–5116 (2004).

We propose an electrically programmable, multi-level non-volatile photonics memory cell (PMC) fabricated by standard CMOS compatible processes. A micro-ring resonator (MRR) was built using the PMC to demonstrate programmable and erase functions.

3D electro-optical integration based on a Cu-based Si-photonics TSV interposer has been demonstrated for integrated optical communication applications. The photonics TSV interposer consisting of monolithically integrated TSV, modulators and photodetectors, enabling a 30 Gbps-data-rate.

Micron-scale disk resonators are explored to minituarize and enhance Ge-on-Si photodetectors. A 2.0 μm-radius detector exhibits a dark current of 11 nA, a responsitivity of 0.5 A/W and a 3-dB bandwidth of 17 GHz at −1V bias.

We demonstrate 10-Gb/s high-on/off-contrast modulation of a carrier-depletion silicon Mach-Zehnder modulator having 3-mm rib-waveguide phase shifter driven with RF 3.6 VPP or lower at temperatures up to 130 °C without thermo-electric cooling.

CMOS-compatible silicon photonics technology is becoming a promising candidate to realize very large-scale complex photonics-CMOS integration system. For the purpose of CMOS-compatible complete-Cu integration, a traveling-wave electrode (TWE) of a silicon optical modulator via Cu-based back-end-of-line (BEOL) process is demonstrated in this work. A latticed Cu surface pattern is designed for the requirement of Cu-BEOL process. The Cu-TWE is modeled on aspects of the group velocity match and the characteristic impedance match. The dual-damascene based Cu-BEOL fabrication process for the TWE and the contact plugs of the modulator is presented. Finally, the experiment and characterization results are presented, and above 30 GHz-bandwidth can be achieved.

We present silicon-based WDM photonics link for 240 Gb/s data transmission on 1.3 μm with above 50 GHz silicon modulator and 20GHz Germanium photo-detector. Photonics link has a bandwidth of 53.4GHz limited by the impedance mismatch.

Latest computational and experimental studies on high-speed monolithic silicon-based Mach-Zehnder optical modulators are studied in the light of photonic integrated circuits for digital coherent communication at a bit rate as fast as 128 Gb/s per wavelength channel. Lateral PN-junction rib-waveguide phase shifters are elaborated with experimental characteristics of DC phase shifter response in comparison with computational characteristics. High-speed response in refractive-index dynamics including electron and hole transport in the PN junction is simulated to study speed limit of the phase shifters. The performance in quadrature phase-shift keying signal generation is characterized in experimental and computational constellation diagrams. Silicon waveguides for polarization-division multiplexing are designed in common design rules with the rib-waveguide phase shifters. Long-haul transmission in polarization-multiplexed quadrature phase-shift keying in 1000-km single-mode fiber link is confirmed with a monolithic silicon Mach-Zehnder modulator assembled with modulator drivers in a ceramic-based metal package.

Slot waveguide based ring resonators filled with atomic layer deposited (ALD) aluminum oxide (Al2O3) were fabricated and characterized. Our results demonstrate that ALD can be used to create slot waveguide ring resonators with relatively high Q-factors, which opens new possibilities for various photonic applications, such as optical sensing and all-optical signal processing.

A novel Si-based metal-oxide-semiconductor (MOS) electrooptic phase modulator including two shunt oxide layer capacitors integrated on a silicon-on-insulator (SOI) waveguide is simulated and analyzed. The refractive index near the two gate oxide layers is modified by the free carrier dispersion effect induced by applying a positive bias on the electrodes. The theoretical calculation of free carrier distribution coupled with optical guided mode propagation characteristics has been carried out. The influence of the structure parameters such as the width and the doping level of the active region are analyzed. A half-wave voltage V/sub /spl pi//=4 V is demonstrated with an 8-mm active region length and a 4-/spl mu/m width of an inner rib under an accumulation mode. When decreasing the inner rib width to 1 /spl mu/m, the phase modulation efficiency is even higher, and the rise and fall times reach 50 and 40 ps, respectively, with a 1.0/spl times/10/sup 17/ cm/sup -3/ doping level in the active region.

We demonstrate a high-efficiency and CMOS-compatible silicon Mach-Zehnder Interferometer (MZI) optical modulator with Cu traveling-wave electrode and doping compensation. The measured electro-optic bandwidth at Vbias = -5 V is above 30 GHz when it is operated at 1550 nm. At a data rate of 50 Gbps, the dynamic extinction ratio is more than 7 dB. The phase shifter is composed of a 3 mm-long reverse-biased PN junction with modulation efficiency (Vπ·Lπ) of ~18.5 V·mm. Such a Cu-photonics technology provides an attractive potentiality for integration development of silicon photonics and CMOS circuits on SOI wafer in the future.

A silicon Cu-photonics interposer, consisting of monolithically integrated Si modulators and Ge photodetectors, has been explored for integrated optical communication. Up to 33.7 GHz-bandwidth of this integrated circuit are enabled by travelling-wave electrode via Cu-BEOL.

We demonstrated the applications of our Si 3 N 4 -on-SOI platform for O-band operation with propagation and interlayer transition loss of ∼0.24dB/cm and ∼0.2dB, respectively. We also characterized our SOI-based Ge photo-detector and silicon modulator at λ= 1310nm.

We proposed a microring resonator (MRR) enhanced photodetector (PD) structure. Resonance wavelength enhanced by the MRR amplifies the PD response. At L-band wavelengths, responsivity was doubled for an ultra-short germanium PD of 4 µm employing the MRR structure. Data rates of up to 40 Gb/s were also demonstrated at 1600 nm.

We demonstrate silicon-based traveling-wave photodetector arrays (Si-TWPDAs) with parallel optical feeding by integrating multiple Germanium photodetectors. Such Si-TWPDAs feature the merit of high optical saturation power with remaining the large operation bandwidth. The impedance-matched traveling-wave electrode design takes into account the individual Ge photodetector loading effect. Optical waveguide delay lines are designed in order to balance the electrical phase delay of the traveling-wave electrode. The maximum linear photocurrent at −4V biased voltage are respectively 16 mA, 38 mA, and 65 mA with integrating 1, 2, and 4 photodetectors, upon the saturation power of 40 mW, 100 mW, and 160 mW. This corresponds to a normalized photocurrent generation of >0.32 mA/µm3 and a normalized saturation power of 0.8 mW/µm3. The extracted fiber access responsivity is ~0.42 A/W and the intrinsic responsivity of ~0.82 A/W. The measured 3-dB bandwidth for 4-channel TWPDA is ~20 GHz.

10-Gb/s silicon-based Mach-Zehnder modulator is packaged and characterized. The I/O sections of the modulator chip are located at longer-facet sides using bends waveguides for enhancing modulation bandwidth by using short straight configuration of traveling-wave electrodes. Low-insertion loss and high-return-loss optical coupling structure between input/output lenses and the modulator chip is achieved with optical coupling, where both of chip facets and inverted-taper mode-field-convertors are angled with respect to incident light beam. 3-dB electro-optic bandwidth is as high as 12.0-GHz and optical insertion loss is 9-dB or lower. High-contrast eye diagram with an extinction ratio of 13.8-dB is obtained.

The wavelength band near 1300 nm is attractive for many telecommunications applications, yet there are few results in silicon that demonstrate high-speed modulation in this band. We present the first silicon modulator to operate at 50 Gbps near 1300 nm. We demonstrate an open eye at this speed using a differential 1.5 V(pp) signal at 0 V reverse bias, achieving an energy efficiency of 450 fJ/bit.

We experimentally realize a cross-slot waveguide based on GaAs-AlGaAs-GaAs substrate carrying both of transverse-electric slot mode and transverse-magnetic slot mode. A low refractive index AlOx layer is formed between two high index GaAs layers by thermal oxidation method. A polarization splitter is obtained through a 25-μm-long ultracompact directional coupler based on the waveguide. The measured result fits well with calculation using the beam-propagation method.

We demonstrate the first silicon-based parallel-fed travelling-wave photodetector array (TWPDA). Impedance-matched travelling-wave electrode is designed considering periodic loading effect. The demonstrated up to 4-channel TWPDAs show >10GHz 3-dB bandwidths and ~0.75A/W responsivity using 30µm-length PDs.

We present a SACM waveguide Ge/Si APD capable of 25 Gb/s operation at 1.3 μm, with a unique low-height-profile structure which enables low dark current. A maximum sensitivity improvement of ~9 dBm can be obtained.

Silicon photonics platform in a commercial 0.18 μm CMOS foundry line is described. Low-loss Si passives and high speed germanium photodetectors (>20GHz) with low dark current (~11nA) and high responsivity (1.06A/W) at 1550nm are presented.

We have designed and demonstrated high efficiency Silicon nitride grating couplers with two periods of distributed Bragg reflectors at 1490 nm. The peak coupling efficiency is ~-2.6 dB and the 1-dB bandwidth is ~53 nm.

We demonstrate silicon Mach-Zehnder Interferometer (MZI) optical modulator with 50.1-Gb/s data rate and 5.56 dB dynamic extinction ratios. The phase shifter is composed by a 4 mm-long reverse-biased p-n junction with a modulation efficiency (V(π) · L(π)) of ~26.7 V · mm and phase shifter loss of ~1.04 dB/mm at V(bias) = -6 V. The measured electro-optic bandwidth reaches 25.6 GHz at V(bias) = -5 V. Compensation doping method and low loss traveling-wave electrodes are utilized to improve the modulator performance. Measurement result demonstrates that reasonable choosing of working point and doping profile of the silicon optical modulator is critical in order to match the performance requirement of the real application.

A carrier-induced silicon-waveguide Bragg-grating filter with a pin junction is demonstrated. The bandwidth and the extinction ratio of the filter are 0.3nm and 14dB, respectively. It can be tuned by both forward and reverse biases.

Monolithic photonic integrated circuit consisting of first-order mode splitter and Ge photodiode is designed, fabricated and characterized for optical performance monitoring of Si Mach-Zehnder modulator. First-order mode splitter is Si waveguide directional coupler with coupling length as short as 16 μm, allowing efficient transfer of first-order mode from main waveguide to sub waveguide. Evanescent-coupling Ge photodiode is fabricated on the sub waveguide. Optical performance monitoring is confirmed with responsivity higher than 50 mA/W in C and L bands.

We demonstrate a cost-effective silicon microring-based bio/chemical sensor, which integrates vertical grating couplers, two cascaded microrings for optical sensing and electrical tracing, and Ge photodetector for direct sensing interrogation. Detection limit of 1.5×10-5 is demonstrated.

Conventional silicon photonic integrated circuits do not normally possess memory functions, which require on-chip power in order to maintain circuit states in tuned or field-configured switching routes. In this context, we present an electrically programmable add/drop microring resonator with a wavelength shift of 426 pm between the ON/OFF states. Electrical pulses are used to control the choice of the state. Our experimental results show a wavelength shift of 2.8 pm/ms and a light intensity variation of ~0.12 dB/ms for a fixed wavelength in the OFF state. Theoretically, our device can accommodate up to 65 states of multi-level memory functions. Such memory functions can be integrated into wavelength division mutiplexing (WDM) filters and applied to optical routers and computing architectures fulfilling large data downloading demands.

Si 3 N 4 strip and slot waveguide passive devices platform are demonstrated based on standard CMOS process including athermal MZI filter, multi-channel ring filter, two-ring EIT and AWG. The loss of Si 3 N 4 strip waveguide is 0.6dB/cm for TE mode and 0.66dB/cm for TM mode. A 20-channel micro-ring filter with 25GHz channel spacing is realized with 15dB cross-talk on this Si 3 N 4 platform. Thermal tuning EIT is demonstrated with two-ring filter structure with heater on one of the ring resonator. A 16-channel AWG is realized with a 100GHz channel spacing and 15 dB extinction ratio.

We demonstrate a multiple-channel optical receiver integrating multiple thermally tunable microring resonator as the WDM demultiplexing and Ge photodetector for light detection. We fabricated 4-channel and 10-channel of such WDM receivers using CMOS-compatible fabrication process. We show that with the thermal tunability, the channel wavelengths can be adjusted to align with the selected channel grid. Proof-of-principle demonstrations using 4-channel receiver shows up to 160 Gbit/s date transmissions with high data quality.

We demonstrate a 4-channel 2×2 colorless WSS with channel spacing of 20nm, the total transmission loss of ~10dB, power consumption of ~2.5mW, and switching time of ~006μs. High-throughput data transmission of 80Gb/s is demonstrated.

Different types of slot waveguide couplers are studied theoretically and experimentally. We present strip-to-slot waveguide couplers with a length as small as 10 μm and with their feature sizes no less than 150 nm, exhibiting efficient coupling into the slot mode and negligible scattering. We demonstrate coupling loss of 0.11 dB for a 20-micron long coupler from a strip waveguide to slot waveguide, fabricated using the 248 nm deep-UV lithography. We also discuss ring resonator couplers, multimode multislot structures for 2x2 couplers, and prism coupling characterization of multislot waveguide structures.

Silicon photonic waveguide nested Mach-Zehnder modulators having rib-waveguide planar P-N junction phase shifters are fabricated and characterized in constellation and transmittance measurements. 20-Gbps QPSK constellation is observed with optical loss lower than 15 dB at wavelengths of 1550 and 1590 nm.

We demonstrate low-loss silicon slot waveguides filled with single and dual atomic layer deposited oxide layers. Propagation losses less than 5 dB/cm and 8 dB/cm are achieved for the waveguides with single (Al 2 O 3 ) and double (Al 2 O 3 -TiO 2 ) layers, respectively. The devices are fabricated using low-temperature CMOS compatible processes. The geometries allow nonlinearities nearly two orders of magnitude smaller than plain silicon waveguides.

We propose and demonstrate a cost effective electrical tracing-assisted silicon microring sensor system which comprises one sensing microring and another thermo-optical-tunable tracing microring. Proof-of-principle demonstation by testing polyelectrolyte multilayer shows the sensitivity of 3.75 mW/ng·mm2.

Micro-cavity structure composed of silicon wire with 240 nm square cross section and two symmetrical sidewall waveguide Bragg gratings is fabricated and studied for the operation under telecommunication wavelengths. Optical filter of quasi-TE mode was realized based on this cavity. In such micro-cavity, optical quality factor (Q) was measured up to 380 with a 4.8 nm free spectral range (FSR) and 12 dB fringe contrast (FC). The measured group index of silicon waveguide with only 240 nm square cross section was between 3.80 and 5.43. It is the first time group delay of silicon wire waveguide with such small core dimension is studied. Larger group delay can be expected after optimizing the design parameters and the fabrication process.

We present detail design considerations and simulation results of a forward biased carrier injection p-i-n modulator integrated on SOI rib waveguides. To minimize the free carrier absorption loss while keeping the comparatively small lateral dimensions of the modulator as required for high speed operation, we proposed two structural improvements, namely the double ridge (terrace ridge) structure and the isolating grooves at both sides of the double ridge. With improved carrier injection and optical confinement structure, the simulated modulator response time is in sub-ns range and absorption loss is minimized.

We present a low-loss and small-footprint polarization rotator based on mode evolution. The polarization rotator is composed of an asymmetric-rib waveguide and a tapered waveguide, both of which consist only of a silicon core and a silica cladding. The rotator is fabricated under the same design rules as other device blocks, such as rib-waveguide phase shifters for photonic integration. The polarization rotator is fabricated using CMOS-based processes and provides polarization rotations with an on-chip insertion loss lower than 0.5 dB from transverse-electric (TE) to transverse-magnetic (TM) polarization and a loss lower than 1.0 dB from the TM to TE polarization in a 200 nm wavelength range extending over C and L bands.

We propose a novel coupled resonator optical waveguide (CROW) structure that is made up of a waveguide loop. We theoretically investigate the forbidden band and conduction band conditions in an infinite periodic lattice. We also discuss the reflection- and transmission- spectra, group delay in finite periodic structures. Light has a larger group delay at the band edge in a periodic structure. The flat band pass filter and flat-top group delay can be realized in a non-periodic structure. Scattering matrix method is used to calculate the effects of waveguide loss on the optical characteristics of these structures. We also introduce a tunable coupling loop waveguide to compensate for the fabrication variations since the coupling coefficient of the directional coupler in the loop waveguide is a critical factor in determining the characteristics of a loop CROW. The loop CROW structure is suitable for a wide range of applications such as band pass filters, high Q microcavity, and optical buffers and so on.

A silicon Mach-Zehnder Interferometer (MZI) optical modulator with a shield coplanar waveguide (CPW) transmission line electrode design was demonstrated. This shield-CPW electrode suppresses the signal distortion caused by the parasitic slot-line (SL) mode and improves the electrical bandwidth and the electro-optical (EO) bandwidth. With the shield-CPW electrodes and 5.5 mm-long phase shifters, the silicon MZI optical modulator delivered an EO bandwidth of above 24 GHz and a V (π) = 3.0 V was achieved at λ = 1310 nm. When modulated at 28-Gb/s data rate, it achieved an extinction ratio of 5.66 dB under a driving voltage of V (pp) = 1.3 V, corresponding to a power consumption of 0.8 pJ/bit.

In this paper we have designed, fabricated and characterized a high efficiency Silicon nitride grating coupler at 1490 nm. Distributed Bragg reflectors as bottom mirrors are employed to improve the coupling efficiency by reflecting the downward traveling light. The peak coupling efficiency obtained is about -2.5 dB and the 1-dB bandwidth is 53 nm. The fabrication process is CMOS-compatible and is ready to be integrated with photonic circuits.

We propose a novel three-dimensional (3D) monolithic optoelectronic integration platform. Such platform integrates both electrical and photonic devices in a bulk silicon wafer, which eliminates the high-cost silicon-on-insulator (SOI) wafer and is more suitable for process requirements of electronic and photonic integrated circuits (ICs). For proof-of-concept, we demonstrate a three-dimensional photodetector and WDM receiver system. The Ge is grown on a 8-inch bulk silicon wafer while the optical waveguide is defined in a SiN layer which is deposited on top of it, with ~4 µm oxide sandwiched in between. The light is directed to the Ge photodetector from the SiN waveguide vertically by using grating coupler with a Aluminum mirror on top of it. The measured photodetector responsivity is ~0.2 A/W and the 3-dB bandwidth is ~2 GHz. Using such vertical-coupled photodetector, we demonstrated an 8-channel receiver by integrating a 1 × 8 arrayed waveguide grating (AWG). High-quality optical signal detection with up to 10 Gbit/s data rate is demonstrated, suggesting a 80 Gbit/s throughput. Such receiver can be applied to on-chip optical interconnect, DRAM interface, and telecommunication systems.