Showing papers on "Extinction ratio published in 2015"

Effective Electro-Optical Modulation with High Extinction Ratio by a Graphene–Silicon Microring Resonator

Abstract: Graphene opens up for novel optoelectronic applications thanks to its high carrier mobility, ultralarge absorption bandwidth, and extremely fast material response. In particular, the opportunity to control optoelectronic properties through tuning of the Fermi level enables electro-optical modulation, optical–optical switching, and other optoelectronics applications. However, achieving a high modulation depth remains a challenge because of the modest graphene-light interaction in the graphene–silicon devices, typically, utilizing only a monolayer or few layers of graphene. Here, we comprehensively study the interaction between graphene and a microring resonator, and its influence on the optical modulation depth. We demonstrate graphene–silicon microring devices showing a high modulation depth of 12.5 dB with a relatively low bias voltage of 8.8 V. On–off electro-optical switching with an extinction ratio of 3.8 dB is successfully demonstrated by applying a square-waveform with a 4 V peak-to-peak voltage.

Graphene-assisted all-fiber phase shifter and switching

Abstract: Optically controlled phase shifters are desirable for optical communication, sensors, and signal processing due to their simple implementation and low cost. We propose an all-fiber phase shifter assisted by graphene’s photothermal effect. In a graphene-coated microfiber, graphene’s ohmic heating promises efficient fiber index change and phase shift via the thermo-optic effect. On a fabricated device with a length of 5 mm, we obtain a phase shift exceeding 21π with a nearly linear slope of 0.091 π/mW (0.192 π/mW) when pumped by 980 nm (1540 nm) light, which enables all-optical switching with an extinction ratio of 20 dB and a rise (fall) time of 9.1 ms (3.2 ms) following the 10%–90% rule. This graphene-assisted index change and phase shifter featured with all-in-fiber, low power requirement, and ease of fabrication may open the door for graphene’s realistic applications in all-optical signal processing.

Large-scale silicon photonic switches with movable directional couplers

Abstract: Fast optical circuit switches (OCSs) with high port count offer reconfigurable bandwidth in optical networks and have the potential to significantly increase the performance and efficiency of modern datacenters. In this paper, we report on a new type of integrated OCS that combines silicon photonics with MEMS actuation. The switch is built on a 50×50 passive crossbar network with very low optical loss (0.04 dB/crossing). Efficient switching is achieved by a pair of directional couplers with moving waveguides and an actuation voltage of 14 V. 2500 MEMS-actuated directional coupler switches have been integrated with the crossbar network to form a strictly nonblocking 50×50 OCS on a 9 mm×9 mm chip. The measured switching time is 2.5 μs, and the extinction ratio is 26 dB. To our knowledge, this is the largest silicon photonic switch reported to date. The switch architecture is highly scalable because the light travels through only one active switching element, regardless of the size of the switch.

Efficient polarization beam splitter pixels based on a dielectric metasurface

Abstract: The polarization dependence of the reflection, refraction, and diffraction of electromagnetic waves from materials is measured in applications that extend from small (e.g., ellipsometry of semiconductor chips) to large scales (e.g., remote sensing for planetary science and weather radar). Such applications employ polarimeters that are in turn based on devices with polarization-selective absorption or reflection/refraction properties (e.g., prisms). The latter devices are generally bulky, thereby limiting their integration into compact systems. The former devices are inherently lossy, as they function by absorbing the unwanted polarization. Here, we experimentally demonstrate a conceptually novel method for pixel-level polarimetry. Each pixel contains amorphous-silicon nanoridges and deflects incident light in a polarization-dependent manner. As photons are sorted by polarization rather than filtered, the approach permits high efficiency. A high transmission efficiency of 90% and a high extinction ratio of 15 times are demonstrated.

463-MHz fundamental mode-locked fiber laser based on few-layer MoS(2) saturable absorber.

Abstract: We report on the passive-mode-locking operation of a fiber laser with a fundamental repetition rate of 463 MHz based on molybdenum disulfide (MoS2) saturable absorber (SA). By embedding MoS2 into polyvinyl alcohol (PVA) thin film, MoS2-PVA SA was prepared with a modulation depth of 2.7% and a saturation intensity of 137 MW/cm2. The mode-locked fiber laser-employed MoS2-PVA SA was achieved with center wavelength of 1556.3 nm, 3-dB bandwidth of 6.1 nm, output power of 5.9 mW, and an extinction ratio of up to 97 dB in the RF spectrum. The demonstration of mode-locking operation with high fundamental repetition rate and high spectral purity indicates that MoS2-PVA SA can be a good candidate for high-precision ultrafast applications.

Heterogeneous microring and Mach-Zehnder modulators based on lithium niobate and chalcogenide glasses on silicon.

Abstract: Thin films of lithium niobate are wafer bonded onto silicon substrates and rib-loaded with a chalcogenide glass, Ge(23)Sb(7)S(70), to demonstrate strongly confined single-mode submicron waveguides, microring modulators, and Mach-Zehnder modulators in the telecom C band. The 200 μm radii microring modulators present 1.2 dB/cm waveguide propagation loss, 1.2 × 10(5) quality factor, 0.4 GHz/V tuning rate, and 13 dB extinction ratio. The 6 mm long Mach-Zehnder modulators have a half-wave voltage-length product of 3.8 V.cm and an extinction ratio of 15 dB. The demonstrated work is a key step towards enabling wafer scale dense on-chip integration of high performance lithium niobate electro-optical devices on silicon for short reach optical interconnects and higher order advanced modulation schemes.

Wavelength-size hybrid Si-VO(2) waveguide electroabsorption optical switches and photodetectors.

Abstract: Ultra-compact waveguide electroabsorption optical switches and photodetectors with micron- and sub-micron lengths and compatible with silicon (Si) waveguides are demonstrated using the insulator-metal phase transition of vanadium dioxide (VO(2)). A 1 μm long hybrid Si-VO(2) device is shown to achieve a high extinction ratio of 12 dB and a competitive insertion loss of 5 dB over a broad bandwidth of 100 nm near λ = 1550 nm. The device, operated as a photodetector, can measure optical powers less than 1 μW with a responsivity in excess of 10 A/W. With volumes that are about 100 to 1000 times smaller than today's active Si photonic components, the hybrid Si-VO(2) devices show the feasibility of integrating transition metal oxides on Si photonic platforms for nanoscale electro-optic elements.

Tunable frequency combs based on dual microring resonators.

Abstract: In order to achieve efficient parametric frequency comb generation in microresonators, external control of coupling between the cavity and the bus waveguide is necessary. However, for passive monolithically integrated structures, the coupling gap is fixed and cannot be externally controlled, making tuning the coupling inherently challenging. We design a dual-cavity coupled microresonator structure in which tuning one ring resonance frequency induces a change in the overall cavity coupling condition. We demonstrate wide extinction tunability with high efficiency by engineering the ring coupling conditions. Additionally, we note a distinct dispersion tunability resulting from coupling two cavities of slightly different path lengths, and present a new method of modal dispersion engineering. Our fabricated devices consist of two coupled high quality factor silicon nitride microresonators, where the extinction ratio of the resonances can be controlled using integrated microheaters. Using this extinction tunability, we optimize comb generation efficiency as well as provide tunability for avoiding higher-order mode-crossings, known for degrading comb generation. The device is able to provide a 110-fold improvement in the comb generation efficiency. Finally, we demonstrate open eye diagrams using low-noise phase-locked comb lines as a wavelength-division multiplexing channel.

All-optical photonic crystal NOT and OR logic gates using nonlinear Kerr effect and ring resonators

Abstract: In this paper, a nonlinear photonic crystal structure is proposed in order to implement all-optical NOT and OR logic gates. The proposed structure includes combiners and limiters. The limiters are designed using ring resonator. Also, the combiners are optimized with changing the radius of rods near the crosspoint of waveguides in order to enhance the performance of structure. Nonlinear rods of proposed structure are made of silicon nanocrystal which has been used in order to create the frequency shift for different values of input power. Plane wave expansion and finite difference time domain methods have been utilized to simulate the performance of proposed logic gate. Simulation results show that the ON–OFF logic-level extinction ratio and bit rate are −18.7 dB and 333 Gbit/s, respectively.

Ultra-high-extinction-ratio 2 × 2 silicon optical switch with variable splitter

Abstract: We demonstrate a record-high extinction-ratio of 50.4 dB in a 2 × 2 silicon Mach-Zehnder switch equipped with a variable splitter as the front 3-dB splitter. The variable splitter is adjusted to compensate for the splitting-ratio mismatch between the front and rear 3-dB splitters. The high extinction ratio does not rely on waveguide crossings and meets a strong demand in applications to multiport circuit switches. Large fabrication tolerance will make the high extinction ratio compatible with a volume production with standard complementary metal-oxide semiconductor fabrication facilities.

Low-loss hollow-core silica fibers with adjacent nested anti-resonant tubes

Abstract: We report on numerical design optimization of hollow-core anti-resonant fibers with the aim of reducing transmission losses. We show that re-arranging the nested anti-resonant tubes in the cladding to be adjacent has the effect of significantly reducing leakage as well as bending losses, and for reaching high loss extinction ratios between the fundamental mode and higher order modes. We investigate two versions of the proposed design, one optimized for the mid-IR and another scaled down version for the near-IR and compare them in detail with previously proposed anti-resonant fiber designs including nested elements. Our proposed design is superior with respect to obtaining the lowest leakage losses and the bend losses are also much lower than for the previous designs. Leakage losses as low as 0.0015 dB/km and bending losses of 0.006 dB/km at 5 cm bending radius are predicted at the ytterbium lasing wavelength 1.06 µm. When optimizing the higher-order-mode extinction ratio, the low leakage loss is sacrificed to get an effective single-mode behavior of the fiber. We show that the higher-order-mode extinction ratio is more than 1500 in the range 1.0-1.1 µm around the ytterbium lasing wavelength, while in the mid-IR it can be over 100 around λ = 2.94 μm. This is higher than the previously considered structures in the literature using nested tubes.

A 25 Gb/s, 4.4 V-Swing, AC-Coupled Ring Modulator-Based WDM Transmitter with Wavelength Stabilization in 65 nm CMOS

Abstract: Silicon photonics devices offer promising solution to meet the growing bandwidth demands of next-generation interconnects. This paper presents a 5 × 25 Gb/s carrier-depletion microring-based wavelength-division multiplexing (WDM) transmitter in 65 nm CMOS. An AC-coupled differential driver is proposed to realize 4 × VDD output swing as well as tunable DC-biasing. The proposed transmitter incorporates 2-tap asymmetric pre-emphasis to effectively cancel the optical nonlinearity of the ring modulator. An average-power-based dynamic wavelength stabilization loop is also demonstrated to compensate for thermal induced resonant wavelength drift. At 25 Gb/s operation, each transmitter channel consumes 113.5 mW and maintains 7 dB extinction ratio with a 4.4 V $_{\rm pp-diff}$ output swing in the presence of thermal fluctuations.

Broadband Electroabsorption Modulators Design Based on Epsilon-Near-Zero Indium Tin Oxide

Abstract: In this paper, we propose a compact silicon (Si) electroabsorption modulator based on a slot waveguide with epsilon-near-zero indium tin oxide materials. In order to integrate the device with low-loss Si strip waveguides, both butt-coupling and evanescent-coupling schemes are investigated. For both cases, our electroabsorption modulator demonstrates a high extinction ratio and a low insertion loss over a wide optical bandwidth.

Ultra-high modulation depth exceeding 2,400% in optically controlled topological surface plasmons

Abstract: Modulating light via coherent charge oscillations in solids is the subject of intense research topics in opto-plasmonics. Although a variety of methods are proposed to increase such modulation efficiency, one central challenge is to achieve a high modulation depth (defined by a ratio of extinction with/without light) under small photon-flux injection, which becomes a fundamental trade-off issue both in metals and semiconductors. Here, by fabricating simple micro-ribbon arrays of topological insulator Bi2Se3, we report an unprecedentedly large modulation depth of 2,400% at 1.5 THz with very low optical fluence of 45 μJ cm(-2). This was possible, first because the extinction spectrum is nearly zero due to the Fano-like plasmon-phonon-destructive interference, thereby contributing an extremely small denominator to the extinction ratio. Second, the numerator of the extinction ratio is markedly increased due to the photoinduced formation of massive two-dimensional electron gas below the topological surface states, which is another contributor to the ultra-high modulation depth.

High Extinction Ratio and Broadband Silicon TE-Pass Polarizer Using Subwavelength Grating Index Engineering

Abstract: We propose and experimentally demonstrate a novel approach to implement a low-loss, broadband, and compact transverse electric (TE)-pass polarizer on a silicon-on-insulator platform. The TE-polarizer utilizes a subwavelength grating (SWG) structure to engineer the waveguide equivalent material index. In this paper, the SWG-based polarizer only supports its fundamental TE mode, whereas the transverse magnetic (TM) mode is suppressed under the cutoff condition, i.e., the TM mode leaks from the waveguide with low reflection. The simulations predict that the bandwidth to achieve a polarization extinction ratio (ER) of 35 dB exceeds 200 nm. Experimentally, the measured polarization ER is ∼30 dB, and the average insertion loss is 0.4 dB in the wavelength range of 1470–1580 nm. The fabricated TE-polarizer has a compact length of 60 $\mu\textrm{m}$ .

Ultra-compact TE-pass polarizer with graphene multilayer embedded in a silicon slot waveguide.

Abstract: A novel silicon slot waveguide TE-pass polarizer with graphene multilayer embedded in the slot is proposed and demonstrated by utilization of the fact that the variation of the modal characteristics for the TM mode is more than that for the TE mode. The designed polarizer is shown to have the ability to significantly suppress the transmission of the TM mode, while well guiding the TE mode. We numerically demonstrate a 7-μm-long polarizer has an ultra-high insertion loss of 31.5 dB for the TM mode and as little insertion loss as 0.2 dB for the TE mode at 1.55 μm. The presented polarizer offers the performance merits including high extinction ratio, ultra-low insertion loss, ultra-compactness, and easy integration with silicon slot waveguides without using any taper.

Dynamically reconfigurable nanoscale modulators utilizing coupled hybrid plasmonics

Abstract: The balance between extinction ratio (ER) and insertion loss (IL) dictates strict trade-off when designing travelling-wave electro-optic modulators. This in turn entails significant compromise in device footprint (L3dB) or energy consumption (E). In this work, we report a nanoscale modulator architecture that alleviates this trade-off while providing dynamic reconfigurability that was previously unattainable. This is achieved with the aide of three mechanisms: (1) Utilization of epsilon-near-zero (ENZ) effect, which maximizes the attainable attenuation that an ultra-thin active material can inflict on an optical mode. (2) Non-resonant coupled-plasmonic structure which supports modes with athermal long-range propagation. (3) Triode-like biasing scheme for flexible manipulation of field symmetry and subsequently waveguide attributes. By electrically inducing indium tin oxide (ITO) to be in a local ENZ state, we show that a Si/ITO/HfO2/Al/HfO2/ITO/Si coupled-plasmonic waveguide can provide amplitude modulation with ER = 4.83 dB/μm, IL = 0.03 dB/μm, L3dB = 622 nm and E = 14.8 fJ, showing at least an order of magnitude improvement in modulator figure-of-merit and power efficiency compared to other waveguide platforms. Employing different biasing permutations, the same waveguide can then be reconfigured for phase and 4-quadrature-amplitude modulation, with actively device length of only 5.53 μm and 17.78 μm respectively.

Hybrid Si-VO(2)-Au optical modulator based on near-field plasmonic coupling.

Abstract: We present a computational design for an integrated electro-optic modulator based on near-field plasmonic coupling between gold nanodisks and a thin film of vanadium dioxide on a silicon substrate. Active modulation is achieved by applying a time-varying electric field to initiate large changes in the refractive index of vanadium dioxide. Significant decrease in device footprint (200 nm x 560 nm) and increase in extinction ratio per unit length (9 dB/µm) compared to state-of-the-art photonic and plasmonic modulators are predicted.

Resonant Visible Light Modulation with Graphene

Abstract: Fast modulation and switching of light at visible and near-infrared (vis-NIR) frequencies is of utmost importance for optical signal processing and sensing technologies. No fundamental limit appears to prevent us from designing wavelength-sized devices capable of controlling the light phase and intensity at gigaherts (and even terahertz) speeds in those spectral ranges. However, this problem remains largely unsolved, despite recent advances in the use of quantum wells and phase-change materials for that purpose. Here, we explore an alternative solution based upon the remarkable electro-optical properties of graphene. In particular, we predict unity-order changes in the transmission and absorption of vis-NIR light produced upon electrical doping of graphene sheets coupled to realistically engineered optical cavities. The light intensity is enhanced at the graphene plane, and so is its absorption, which can be switched and modulated via Pauli blocking through varying the level of doping. Specifically, we explore dielectric planar cavities operating under either tunneling or Fabry-Perot resonant transmission conditions, as well as Mie modes in silicon nanospheres and lattice resonances in metal particle arrays. Our simulations reveal absolute variations in transmission exceeding 90% as well as an extinction ratio >15 dB with small insertion losses using feasible material parameters, thus supporting the application of graphene in fast electro-optics at vis-NIR frequencies.

Reflective all-fiber magnetic field sensor based on microfiber and magnetic fluid.

Abstract: A kind of reflective all-fiber magnetic field sensor based on a non-adiabatically tapered microfiber with magnetic fluid is proposed and experimentally demonstrated. The modal interference effect is caused by the abrupt tapers, which result in an approximately sinusoidal spectral response. The reflection spectra of the proposed sensor under different magnetic field strengths have been measured and theoretically analyzed. The maximum sensitivity of 174.4 pm/Oe is achieved at wavelength of around 1511 nm. Besides, an intensity tunability of −0.02 dB/Oe is also achieved. Comparing with the traditional sensors operating at transmission mode, the presented sensor in this work owns the advantages of smaller size and higher sensitivity and resolution due to the enhanced extinction ratio. The proposed structure is also promising for designing other tunable all-in-fiber photonic devices.

Tunable frequency combs based on dual microring resonators

Abstract: In order to achieve efficient parametric frequency comb generation in microresonators, external control of coupling between the cavity and the bus waveguide is necessary. However, for passive monolithically integrated structures, the coupling gap is fixed and cannot be externally controlled, making tuning the coupling inherently challenging. We design a dual-cavity coupled microresonator structure in which tuning one ring resonance frequency induces a change in the overall cavity coupling condition. We demonstrate wide extinction tunability with high efficiency by engineering the ring coupling conditions. Additionally, we note a distinct dispersion tunability resulting from coupling two cavities of slightly different path lengths, and present a new method of modal dispersion engineering. Our fabricated devices consist of two coupled high quality factor silicon nitride microresonators, where the extinction ratio of the resonances can be controlled using integrated microheaters. Using this extinction tunability, we optimize comb generation efficiency as well as provide tunability for avoiding higher-order mode-crossings, known for degrading comb generation. The device is able to provide a 110-fold improvement in the comb generation efficiency. Finally, we demonstrate open eye diagrams using low-noise phase-locked comb lines as a wavelength-division multiplexing channel.

Ultra-compact broadband higher order-mode pass filter fabricated in a silicon waveguide for multimode photonics.

Abstract: An ultra-compact and broadband higher order-mode pass filter in a 1D photonic crystal silicon waveguide is proposed and experimentally demonstrated The photonic crystal is designed for the lower order mode to work in the photonic band gap, while the higher order mode is located in the air band Consequently, light on the lower order mode is prohibited to pass through the filter, while light on a higher order mode can be converted to a Bloch mode in the photonic crystal and pass through the filter with low insertion loss As an example, we fabricate a ∼15-μm-long first-order-mode pass filter that filters out the fundamental mode and provides a measured insertion loss of ∼18 dB for the first-order-mode pass signals The extinction ratio is measured to be around 50 dB (with a variation of ±10 dB due to the detection limitation of the measurement setup) in the measured wavelength range from 1480 to 1580 nm Additionally, calculations predict the extinction ratio to be larger than 50 dB in a 170 nm broad bandwidth

A compact plasmonic MOS-based 2x2 electro-optic switch

Abstract: We report on a three-waveguide electro-optic switch for compact photonic integrated circuits and data routing applications. The device features a plasmonic metal-oxide-semiconductor (MOS) mode for enhanced light-matter-interactions. The switching mechanism originates from a capacitor-like design where the refractive index of the active medium, Indium-Tin-Oxide, is altered via shifting the plasma frequency due to carrier accumulation inside the waveguide-based MOS structure. This light manipulation mechanism controls the transmission direction of transverse magnetic polarized light into either a CROSS or BAR waveguide port. The extinction ratio of 18 dB (7) dB for the CROSS (BAR) state, respectively, is achieved via a gating voltage bias. The ultrafast broadband fJ/bit device allows for seamless integration with Siliconon- Insulator platforms to for low-cost manufacturing.

Vertical split-ring resonator based anomalous beam steering with high extinction ratio.

Abstract: Metasurfaces created artificially with metal nanostructures that are patterned on surfaces of different media have shown to possess “unusual” abilities to manipulate light. Limited by nanofabrication difficulties, so far most reported works have been based on 2D metal structures. We have recently developed an advanced e-beam process that allowed for the deposition of 3D nanostructures, namely vertical split-ring resonators (VSRRs), which opens up another degree of freedom in the metasurface design. Here we explore the functionality of beam steering with phase modulation by tuning only the vertical dimension of the VSRRs and show that anomalous steering reflection of a wide range of angles can be accomplished with high extinction ratio using the finite-difference-time-domain simulation. We also demonstrate that metasurfaces made of 3D VSRRs can be made with roughly half of the footprint compared to that of 2D nano-rods, enabling high density integration of metal nanostructures.

Broadband Single-Polarization Photonic Crystal Fiber Based on Surface Plasmon Resonance for Polarization Filter

Abstract: A broadband single-polarization photonic crystal fiber polarized filter based on surface plasmon resonance is proposed based on finite element method. Numerical simulations show the confinement loss of y-PCM (y-polarized core mode) is much higher than that of x-PCM (x-polarized core mode) in the wavelength range 1.20–1.63 μm. The confinement loss of y-polarized mode is 45,240 and 10,200 dB/m at the communication wavelength 1.31 and 1.55 um, respectively, and the corresponding loss of x-polarized mode is just 90 and 80 dB/m. When the fiber length is 3 mm, the bandwidth of extinction ratio better than -20 dB is greater than 430 nm covering almost all the communication wavelength. To our best knowledge, the bandwidth is the widest. The impacts of structural parameters on the resonance characteristics are also discussed. The structure could be further optimized for better result.

Active Control of Graphene-Based Unidirectional Surface Plasmon Launcher

Abstract: The manipulation of surface plasmon polariton (SPP) propagation is a basic subject for the realization of novel optical devices. Although the unidirectional SPP launcher has been demonstrated, it has been difficult to realize active control suitable for device applications. Here, we propose a graphene device with electrically controllable propagation of SPPs. The source/drain electrode of this device is made of a reflective antenna pair structure, with its optical resonance controlled by the corresponding applied voltage. With appropriate source and drain bias, this device can serve as a good unidirectional SPP launcher, with a high extinction ratio over 2000 and generation efficiency of 0.38. The electrical control allows us to tune the propagation of SPPs with significant flexibility, which may be used for future novel plasmonic devices and photonic circuits.

Ultracompact TE-Pass Polarizer Based on a Hybrid Plasmonic Waveguide

Abstract: An ultracompact and broadband TE-pass polarizer based on a hybrid plasmonic waveguide is proposed on the silicon-on-insulator platform. The optimized design has an active region as small as $0.8~\mu $ m, which is the shortest polarizer reported until now, and exhibits high polarization-dependent transmission imposing a TM mode cutoff while leaving the TE mode almost unaffected. Finite-difference time-domain simulation reveals an insertion loss <1 dB and an extinction ratio of 19 dB. The extinction ratio could be further improved to 25 dB over 300-nm bandwidth, with an insertion loss of 2.5 dB.

Ultra-broadband and compact polarization splitter based on gold filled dual-core photonic crystal fiber

Abstract: A polarization splitter based on gold filled dual-core photonic crystal fiber (DC-PCF) that can work from 1420 nm to 1980 nm (560 nm bandwidth) is proposed in this work. The splitter has an extinction ratio lower than −20 dB over a large bandwidth with a total length of 254.6 μm. The key principle of operation of the splitter is the induced change in the refractive index of the y-odd mode when it is coupled to the second order plasmonic mode, while other supermodes are weakly affected by the plasmonic mode. The proposed broadband and compact polarization splitter may find applications in communications and sensing, being capable of working in the infrared and mid-infrared wavelength ranges.

Demonstration of a High Extinction Ratio Monolithic CMOS Integrated Nanophotonic Transmitter and 16 Gb/s Optical Link

Abstract: We present a 16-Gb/s transmitter composed of a stacked voltage-mode CMOS driver and periodic-loaded reverse biased pn junction Mach–Zehnder modulator. The transmitter shows 9-dB extinction ratio and 10.3-pJ/bit power consumption and operates with 1.3 μm light. Penalties as low as 0.5 dB were seen as compared to a 25-Gb/s LiNbO3 transmitter with both a monolithic metal–semiconductor–metal receiver and a reference receiver at 16-Gb/s operation. We also present an analytic expression for relative transmitter penalty (RTP), which allows one to quickly assess the system impact of design parameters such as peak-to-peak modulator drive voltage, modulator figure of merit, and transmitter extinction ratio to determine the circumstances under which a stacked CMOS cascode driver is desirable.