Showing papers on "Extinction ratio published in 2022"

A 50-Gb/s PAM-4 Silicon-Photonic Transmitter Incorporating Lumped-Segment MZM, Distributed CMOS Driver, and Integrated CDR

Abstract: This article presents a 50-Gb/s optical transmitter (TX), consisting of a 40-nm distributed CMOS driver and a 180-nm silicon-photonic modulator. A lumped-segment Mach–Zehnder modulator (LS-MZM) is developed for high bandwidth (BW) four-level pulse amplitude (PAM-4) modulation. A multi-segment driver with limiting outputs is co-designed, which is distributed into each LS-MZM segment. By grouping these LS-MSM segments in a thermometer code, high-linearity modulation is realized without the need of power-hungry high-swing linear drivers. To improve the optical PAM-4 signal integrity, in-segment multiplexing along with clock phase interpolation is adopted to synchronize the electrical and optical signals across all segments. The hybrid coupling between the driver and modulator is devised to boost the BW of the high-speed data path, while a half-rate clock and data recovery (CDR) circuit is integrated to remove the accumulated jitter. Measurements show that the TX exhibits an extinction ratio (ER) of up to 9.8 dB and a 0.99 ratio of the level mismatch. A figure-of-merit (FoM) of 1.39 pJ/bit/dB corresponds to a 682-mW power, which can be further reduced by 40%, at the cost of a degraded ER of 4 dB. The PAM-4 CDR helps to achieve $< 10^{-12}$ BER and >0.1- $\text{U}I_{\mathrm {pp}}$ jitter tolerance (JTOL) from 10 to 100 MHz.

Monolithic thin film lithium niobate electro-optic modulator with over 110 GHz bandwidth

Abstract: High-performance thin film lithium niobate (LN) electro-optic modulators with low cost are in demand. Based on photolithography and wet etching, we experimentally demonstrate a thin film LN Mach–Zehnder modulator with a 3 dB bandwidth exceeding 110 GHz, which shows the potential of boosting the throughput and reducing cost. The fabricated modulator also exhibits a comparable low half-wave voltage-length product of ∼2.37 V·cm, a high extinction ratio of >23 dB, and the propagation loss of optical waveguides of ∼0.2 dB/cm. Besides, six-level pulse amplitude modulation up to 250 Gb/s is successfully achieved.

Broadband and Short-Length Polarization Splitter on Dual Hollow-Core Antiresonant Fiber

Abstract: We present a compact polarization splitter on a dual hollow-core antiresonant fiber with broad bandwidth covering two well-known communication wavelengths of $1.31~\mu \text{m}$ and 1.55 $\mu \text{m}$ . It can achieve excellent polarization splitting performances in a simpler optimized single-layer geometry compared to the related splitters and for the first time, simultaneously offers a very short splitter length of 21.52 mm and a broad bandwidth of 340 nm by maintaining an extinction ratio higher than 20 dB. It also achieves the highest extinction ratio of 140 dB at $1.55~\mu \text{m}$ and maintains a standard single mode performance. Therefore, the proposed splitter has the potentiality to be a promising candidate for the integrated optical devices in communication systems.

Silicon nitride waveguide polarization rotator and polarization beam splitter for chip-scale atomic systems

Abstract: The design, fabrication, and characterization of a silicon nitride waveguide polarization rotator and polarization beam splitter that operate with a polarization extinction ratio (PER) of ∼30 dB at the rubidium atomic transition of 780 nm wavelength are demonstrated. These polarization devices are fabricated on the same chip using a self-aligned process for integration of the rib and ridge waveguide structures. The polarization rotator is based on the mode evolution approach using adiabatic tapers and demonstrates a PER of ≥20 dB over a 100 nm bandwidth (730–830 nm wavelengths) with an insertion loss (IL) ≤1 dB. The polarization beam splitter is based on a cascaded tapered asymmetric directional coupler with phase matching between the fundamental and higher order TM modes, whereas the TE mode is separated by the through port. This provides a PER ≥ 20 dB with IL ≤ 1 dB over a 50 nm bandwidth for the cross port and a PER ≥ 15 dB with an IL ≤ 1 dB over an 18 nm bandwidth for the through port. These polarization control waveguide devices will enable photonic integrated circuits for saturated absorption spectroscopy of atomic vapors for laser stabilization on-chip.

Compact thin film lithium niobate folded intensity modulator using a waveguide crossing.

Abstract: A small footprint, low voltage and wide bandwidth electro-optic modulator is critical for applications ranging from optical communications to analog photonic links, and the integration of thin-film lithium niobate with photonic integrated circuit (PIC) compatible materials remains paramount. Here, a hybrid silicon nitride and lithium niobate folded electro-optic Mach Zehnder modulator (MZM) which incorporates a waveguide crossing and 3 dB multimode interference (MMI) couplers for splitting and combining light is reported. This modulator has an effective interaction region length of 10 mm and shows a DC half wave voltage of roughly 4.0 V, or a modulation efficiency (Vπ ·L) of roughly 4 V·cm. Furthermore, the device demonstrates a power extinction ratio of roughly 23 dB and shows .08 dB/GHz optical sideband power roll-off with index matching fluid up to 110 GHz, with a 3-dB bandwidth of 37.5 GHz.

Low-power all-optical switch based on a graphene-buried polymer waveguide Mach-Zehnder interferometer.

Abstract: We propose a low-power all-optical switch based on the structure of a graphene-buried balanced Mach-Zehnder interferometer (MZI), where the signal light is switched between the two output ports of the MZI by the heat generated from graphene's absorption of the pump light. We use orthogonal polarizations for the pump and the signal light to maximize pump absorption and minimize graphene-induced signal loss. Our experimental device fabricated with polymer waveguides buried with 5-mm long graphene shows a pump absorption of 10.6 dB (at 980 nm) and a graphene-induced signal loss of 1.1 dB (at 1550 nm) and can switch the signal light with a pump power of 6.0 mW at an extinction ratio of 36 dB. The actual pump power absorbed by graphene for activating switching is estimated to be 2.2 mW. The rise and fall times of the switch are 1.0 and 2.7 ms, respectively. The switching characteristics are weakly sensitive to ambient temperature variations. Our device can be butt-coupled to single-mode fibers and could find applications in fiber-based and on-chip all-optical signal processing.

High-performance silicon polarization switch based on a Mach–Zehnder interferometer integrated with polarization-dependent mode converters

Abstract: Abstract As the key element for optical systems, polarization controllers with versatile functionalities are highly desired. Here, a CMOS-compatible polarization switch is proposed and realized by using a Mach–Zehnder interferometer integrated with two polarization-dependent mode converters (PDMCs) at the input/output ends. The PDMCs, which utilize the mode hybridness and adiabatic mode evolution in a silicon-on-insulator (SOI) ridge waveguide taper, provide a low-loss adiabatic transmission for the launched TE0 mode as well as efficient mode conversion from the launched TM0 mode to the TE1 mode. For the MZI structure, there are two 1 × 2 dual-mode 3-dB power splitters based on a triple-core adiabatic taper, and two thermally-tunable phase-shifters embedded in the arms. The polarization state and the polarization extinction ratio (PER) of the transmitted light can be dynamically tuned by introducing some phase difference between the MZI arms electrically. The fabricated device has an excess loss of ∼0.6 dB for the TE0 and TM0 modes. When the switch is off, the TE0 and TM0 modes go through the device without exchange. In contrast, when the switch is on, the TE0–TM0 conversion occurs and the measured PER is about 20 dB.

Design and characteristic analysis of an all-optical AND, XOR, and XNOR Y-shaped MIM waveguide for high-speed information processing.

Abstract: All-optical logic gates are exceptionally suited for Boolean ultrahigh-speed operation and logical computing. This study presents a plasmonic model that uses a Y-shaped metal-insulator-metal waveguide structure that realizes the ultrafast all-optical AND, XOR, and XNOR gate operation that is developed at a footprint of 6.6µm×3.4µm with a wavelength of 1.55 µm. This construction relies on the notion of linear interference. The insertion loss and extinction ratio of the model are observed as 1.49 dB and 21.49 dB for AND, 1.03 dB and 18.97 dB for XOR, and 2.06 dB, and 10.92 dB for XNOR, respectively. The transmission efficiency, response time, and speed of the structure also are calculated and are used to improve the performance of any complex circuit in the future. The theoretical analysis of the proposed structure is carried out using the finite-difference time-domain method.

Single-Frequency 336 W Spliceless All-Fiber Amplifier Based on a Chirally-Coupled-Core Fiber for the Next Generation of Gravitational Wave Detectors

Abstract: Specialty fibers such as chirally-coupled-core fibers show a high potential for further power scaling of single-frequency fiber amplifiers. For the first time, we demonstrate a spliceless all-fiber amplifier, where all optical components are directly integrated in a single Yb$^{3+}$-doped 3C-fiber. Such a spliceless laser design enables a compact and robust architecture using specialty fibers, while maintaining excellent beam properties. At an output power of 336 W operating at 1064 nm, a fundamental mode content of 90.4% at a polarization extinction ratio above 13 dB was measured without any impact of transverse mode instabilities or other parasitic effects. This work emphasizes the field of applications of 3C-fibers in high-power laser systems.

Silicon Thermo-Optic Switches with Graphene Heaters Operating at Mid-Infrared Waveband

Abstract: The mid-infrared (MIR, 2–20 μm) waveband is of great interest for integrated photonics in many applications such as on-chip spectroscopic chemical sensing, and optical communication. Thermo-optic switches are essential to large-scale integrated photonic circuits at MIR wavebands. However, current technologies require a thick cladding layer, high driving voltages or may introduce high losses in MIR wavelengths, limiting the performance. This paper has demonstrated thermo-optic (TO) switches operating at 2 μm by integrating graphene onto silicon-on-insulator (SOI) structures. The remarkable thermal and optical properties of graphene make it an excellent heater material platform. The lower loss of graphene at MIR wavelength can reduce the required cladding thickness for the thermo-optics phase shifter from micrometers to tens of nanometers, resulting in a lower driving voltage and power consumption. The modulation efficiency of the microring resonator (MRR) switch was 0.11 nm/mW. The power consumption for 8-dB extinction ratio was 5.18 mW (0.8 V modulation voltage), and the rise/fall time was 3.72/3.96 μs. Furthermore, we demonstrated a 2 × 2 Mach-Zehnder interferometer (MZI) TO switch with a high extinction ratio of more than 27 dB and a switching rise/fall time of 4.92/4.97 μs. A comprehensive analysis of the device performance affected by the device structure and the graphene Fermi level was also performed. The theoretical figure of merit (2.644 mW−1μs−1) of graphene heaters is three orders of magnitude higher than that of metal heaters. Such results indicate graphene is an exceptional nanomaterial for future MIR optical interconnects.

Integrated Subwavelength Gratings on a Lithium Niobate on Insulator Platform for Mode and Polarization Manipulation

Abstract: Lithium niobate on insulator (LNOI) has emerged as a promising platform for photonic integrated circuits, with a fast‐growing toolbox of components. This paper proposes, designs, and experimentally demonstrates compact subwavelength grating (SWG) waveguides on an LNOI platform for on‐chip mode and polarization manipulation. To overcome the limitation of waveguide fabrication, the SWGs are designed and formed on a silicon nitride thin film deposited onto the surface of LNOI chip. As proof‐of‐concept devices, the SWG‐based spatial mode filters (including a TE1‐mode‐pass filter and a TE2‐mode‐pass filter) and a TM‐pass polarizer are fabricated successfully on the same chip, with the device lengths of only ≈50 μm. The measured insertion losses for the devices are lower than 3.1 dB, with high extinction ratio larger than 30 dB, at a wavelength of 1550 nm. The proposed and demonstrated SWGs can serve as important building blocks in a series of mode and polarization handling devices for LNOI integrated photonics.

Single-polarization single-frequency Brillouin fiber laser that emits almost 5 W of power at 1 µm.

Abstract: We demonstrate a high-power single-polarization single-frequency 1064 nm Brillouin fiber laser (BFL) that is constructed with polarization-maintaining germanium-doped fiber with a core/cladding diameter of 20/400 µm. A maximum output power of 4.9 W is achieved with a slope efficiency of 68% and an optical signal-to-noise ratio of 65 dB. To the best of our knowledge, this is the highest power output from a single-frequency fiber laser. The polarization extinction ratio is over 18.7 dB and the BFL output presents a good transverse mode. The BFL shows a significant reduction (10-15 dB) in both the relative intensity noise and frequency noise of the pump source, while the estimated linewidth is 170 kHz with a measurement time of 2 ms at the maximum output power. It is believed that the high power output in combination with the decreased relative intensity and frequency noise renders the proposed BFL an important candidate for applications in optical sensing and high-purity microwave signal synthesis.

High extinction ratio and low backreflection polarization maintaining hollow-core to solid-core fiber interconnection.

Abstract: We develop a hybrid cold/heat two-step splicing approach for low loss, low backreflection, and high polarization extinction ratio (PER) hollow-core to solid-core fiber interconnection. The employed hollow-core fiber (HCF) is our recently developed high-birefringence polarization-maintaining hollow-core fiber (PM-HCF) with a PER value of ∼30 dB, and the solid-core fiber (SCF) is a commercial Panda polarization-maintaining fiber (Panda fiber). Simultaneous low backreflection (<-35 dB), low insertion loss (IL) (∼0.7 dB), and high PER (∼27 dB) are achieved, representing the first high-performance PM-HCF/SCF interconnections, to the best of our knowledge. This greatly facilitates the applications of PM-HCF in widespread fields such as precise metrologies, gyroscopes, and ultrafast/high-power laser deliveries.

Broadband Single‐Chip Full Stokes Polarization‐Spectral Imaging Based on All‐Dielectric Spatial Multiplexing Metalens

Abstract: Compared with intensity imaging, more inherent information of objects can be obtained by polarization and multispectral imaging. Here, a broadband and highly integrated single‐chip full Stokes polarization‐spectral (FSPS) imaging is demonstrated using all‐dielectric spatially multiplexed metalens (SMM) in the wavelength band from 1400 to 1700 nm. The proposed FSPS‐SMM is composed of three sets of off‐axis sub‐metalens simultaneously working for pairs of 0°/90°, 45°/135° linear polarization (LP), and left‐handed/right‐handed circular polarization (CP), respectively. Experimental results show that the optical resolution of each sub‐metalens of the fabricated FSPS‐SMM reaches the diffraction limit of the full‐aperture metalens although the area of each sub‐metalens is only 1/3 of the entire metalens, the averaged polarization extinction ratio of both LP and CP reaches 32.8:1, and the energy efficiency reaches 81.8% at the design wavelength and 60% averagely in the whole 300 nm bandwidth, which breaks the 50% limit of conventional polarizer‐based methods. The proposed design provides a new idea for high‐efficiency and high‐resolution full Stokes polarization‐spectral imaging and multichannel information processing.

Quadruple plasmon-induced transparency and tunable multi-frequency switch in monolayer graphene terahertz metamaterial

Abstract: A monolayer graphene metamaterial composed of a graphene block and four graphene strips, which has the metal-like properties in terahertz frequency range, is proposed to generate an outstanding quadruple plasmon-induced transparency (PIT). Additional analyses show that the forming physical mechanism of the PIT with four transparency windows can be explained by strong destructive interference between the bright mode and the dark mode, and the distributions of electric field intensity and electric field vectors under the irradiation of the incident light. Coupled mode theory and finite-difference time-domain method are employed to study the spectral response characteristics of the proposed structure, and the theoretical and simulated results are in good agreement. It is found that a tunable multi-frequency switch and excellent optical storage can be achieved in the wide PIT window. The maximum modulation depth is up to 99.7%, which corresponds to the maximum extinction ratio of 25.04 dB and the minimum insertion loss of 0.19 dB. In addition, the time delay is as high as 0.919 ps, the corresponding group refractive index is up to 2755. Thus, the proposed structure provides a new method for the design of terahertz multi-frequency switches and slow light devices.

Strain-Insensitive Temperature Sensor Based on Few-Mode Fiber and Photonic Crystal Fiber

Abstract: Based on few-mode fiber (FMF) and photonic crystal fiber (PCF), a new temperature sensor with a FMF-PCF-FMF hybrid construction has been developed. Furthermore, the sensor has a longitudinally symmetrical structure that makes it have a flexible sensor head, which enhances the practical performance. Simulated results show that there are three resonant peaks with extinction ratio above 18 dB in the wavelength from 1630 nm to 1720 nm, and the temperature can be measured by calculating wavelength shift of resonant peaks. The experimental results show that the temperature sensitivity of the proposed sensor is as high as 38.6 pm/°C when the temperature ranges from 20°C to 80°C. Meanwhile, the strain sensitivity of the proposed sensor is as low as −0.457 pm/μϵ when strain ranges from 0 to 3000 μϵ. The high temperature sensitivity and ultralow strain sensitivity indicate that the proposed sensor can effectively eliminate the cross-sensitive issue of temperature and strain. In addition to excellent sensing performances, simple and compact structure make the proposed sensor be potential in practical applications.

Highly birefringent polarization maintaining low-losses single-mode hollow-core antiresonant fiber

Abstract: In this paper, a highly birefringent polarization maintaining low losses and a single mode antiresonant hollow core fiber is proposed and analyzed, that is able to exhibit better performances compared to the recent related structures. The usage of bi-thickness cladding tubes with additional high refractive index layers on our geometrically optimized structure improves birefringence nearly by one order: the highest birefringence is 4.7 × 10 −4 at 1.51 µm and sustains > 1 × 10 −4 for a wide bandwidth of 100 nm with a larger core diameter of 26 µm. Elliptical nesting on our proposed structure lowers the confinement loss to 0.007 dB/m at 1.51 µm and maintains a loss of < 1 dB/m for a wide range of 210 nm. A polarization extinction ratio of 300 and higher order mode extinction ratio of 63, for our fiber, ensure a single polarization and single mode operation at 1.51 µm. Moreover, the proposed fiber exhibits a bend robust performance with a very low bend loss of 0.009 dB/m at a small bend radius of 6 cm and sustains a bend loss of < 0.01 dB/m from a bend radius of 4 cm and above. Hence, our presented fiber, containing the above excellent characteristics, may be fruitful for designing polarization-controlled devices (fiber optic sensors, fiber optic amplifiers, fiber optic gyroscope, etc.) in the field of optical communication.

3.96 kW All-Fiberized Linearly Polarized and Narrow Linewidth Fiber Laser with Near-Diffraction-Limited Beam Quality

Abstract: In this paper, we realize a 3.96 kW all-fiberized and polarization-maintained (PM) amplifier with narrow linewidth and near-diffraction-limited beam quality. Based on a master oscillator power amplifier (MOPA) configuration seeded with phase-modulated single-frequency laser, a 3.96 kW signal laser is achieved with a 3 dB linewidth of 0.62 nm at the pump power of 5.02 kW. At the maximum output power, the polarization extinction ratio (PER) is ~13.9 dB, and the beam quality (M2 factor) is M2x = 1.31, M2y = 1.41. As far as we know, this is the maximum output power of PM narrow linewidth fiber laser with near-diffraction-limited beam quality and all-fiber format.

Ultra‐compact and ultra‐broadband hybrid plasmonic‐photonic vertical coupler with high coupling efficiency, directivity, and polarisation extinction ratio

Abstract: An ultra-compact, ultra-broadband vertical coupler for dense photonic integrated circuits is reported with a 1.07 × 0.62 μm2 wavelength-scale footprint. This hybrid plasmonic-photonic coupler uses a unique two-plane plasmonic nanoantenna array on a silicon-on-insulator waveguide. The in- and out-of-plane interference of the multipole moments and dual-feed nanoantennas results in efficient, unidirectional coupling. Finite-element simulations show that, for a 0.8 μm diameter Gaussian beam, the maximum coupling efficiency (CE) is −3.4 dB across the telecommunication C-, L- and U-bands with a 3-dB bandwidth of 230 nm. The CE is > 9 dB higher than recently reported ultra-compact plasmonic couplers. The maximum directivity and polarisation extinction ratio across the C- to U-bands are 9.2 and 24.1 dB, respectively. Finally, as an out-coupler, it has a vertical directivity of >8.5 dB, enabling its use for vertical optical interconnects between two vertically separated circuits.

Mode-locked erbium-doped fiber laser based on a mechanically exfoliated ReS₂ saturable absorber onto D-shaped optical fiber

Abstract: In this work, we report a femtosecond mode-locking Erbium-doped fiber laser using mechanically exfoliated rhenium disulfide (ReS 2 ) deposited onto the polished surface of a D-shaped optical fiber. By performing the polarization and saturable absorption measurements, the sample exhibited a polarization extinction ratio of 10 dB (90%) and nonlinear transmittance variation of 3.40%. When incorporated into the cavity as a saturable absorber (SA), the passive mode-locking performance of 220 fs was achieved. This is the best mode-locking performance ever reported in literature achieved with all-fiber based ReS 2 SA. By using density functional theory (DFT) calculations, we obtained the electronic states and the optical absorption spectrum at 1550 nm attributed by defects in the ReS 2 structures, which is consistent with its linear and nonlinear optical absorption in the laser mode-locking mechanism.

Enhanced all-optical Y-shaped plasmonic OR, NOR and NAND gate models, analyses, and simulation for high speed computations

Abstract: In this digital era, all-optical logic gates (OLGs) proved its effectiveness in execution of high-speed computations. A unique construction of an all-optical OR, NOR, and NAND gates based on the notion of power combiner employing metal–insulator-metal (MIM) waveguide in the Y-shape with a minimal imprint of 6.2 µm × 3 µm is presented and the structure is evaluated by finite-difference time-domain (FDTD) technique. The insertion loss (IL) and extinction ratio (ER) for proposed model are 6 dB and 27.76 dB for NAND gate, 2 dB and 20.35 dB for NOR gate and 6 dB and 24.10 dB for OR respectively. The simplified model is used in the construction of complex circuits to achieve greater efficiency, which contributes to the emergence of a new technique for designing plasmonic integrated circuits.

Group-velocity-locked vector solitons and dissipative solitons in a single fiber laser with net-anomalous dispersion

Abstract: Laser cavities which can generate different types of ultrashort pulses are attractive for practical applications and the study of pulse dynamics. Here, we report the first experimental observation of both conventional solitons (CS) and dissipative solitons (DS) generated from a single all-fiber laser with net-anomalous dispersion. A birefringence-related intracavity Lyot filter with an adjustable extinction ratio enables the switching between the two types of ultrashort pulses. Depending on the polarization controller settings and the pump power, either chirp-free CS with a pulse energy of 406 pJ and a spectral bandwidth of 5.1 nm or up-chirped DS with a pulse energy of 5.1 nJ and an optical bandwidth of 9.6 nm can be generated. Similar polarization features are observed when the laser switches between different soliton operations as both CS and DS are group-velocity-locked vector solitons. Our work paves a novel way to generate dissipative solitons with a relatively high pulse energy (one order of magnitude larger than for CS) and a large chirp directly from an all-fiber net-anomalous-dispersion cavity through birefringent filter management.

50G-PON Downstream Link up to 40 km With a 1342 nm Integrated EML+SOA

Abstract: A monolithically integrated EML+SOA delivering an output power of +13 dBm is demonstrated as a compact Tx for the 50G-PON downstream link. The device delivers +13 dBm of output power with 6 dB extinction ratio and 55 dB/0.1nm OSNR while also passing the 50G-PON eye mask. By exploiting SOA chirp reduction correlated to the gain saturation effects we demonstrate enhanced fiber transmission performance. Since 50G-PON is going to be the first PON technology to adopt digital signal processing (DSP), we use receiver side equalization (EQ) in a 20 km link to demonstrate a link budget of 35.8 dB. Furthermore, working in conjunction with the 50G-PON equalizer, a link up to 40 km SSMF at 1342 nm is realized.

Resonant multilevel optical switching with phase change material GST

Abstract: Abstract We demonstrate a multilevel optical memristive switch based on a silicon Fabry–Perot resonator. The resonator is constructed by a pair of waveguide Bragg gratings at the ends of a multimode interferometer (MMI) covered with sub-micrometer-size Ge2Sb2Te5 (GST) thin film on top. The interaction between the optical field and GST is greatly enhanced due to the resonant effect. The GST phase transition is triggered by applying electrical pulses to the doped-silicon microheater. Light is transmitted when GST is amorphous while it is highly absorbed by the crystalline GST at the resonance wavelength, leading to a higher on-off extinction ratio (ER) compared to the non-resonant device. The resonant device achieves a maximum transmission contrast of 10.29 dB and a total of 38 distinct nonvolatile switching levels. Our work provides an effective solution to improving the multilevel switching performance of phase-change devices and paves the way for future nonvolatile silicon photonics devices.

Electrical control of all-optical graphene switches

Abstract: Graphene has emerged as an ultrafast photonic material for on-chip all-optical switching applications. However, its atomic thickness limits its interaction with guided optical modes, resulting in a high switching energy per bit. Herein, we propose a novel technique to electrically control the switching energy of an all-optical graphene switch on a silicon nitride waveguide. Using this technique, we theoretically demonstrate a 120 µm long all-optical graphene switch with an 8.9 dB extinction ratio, 2.4 dB insertion loss, a switching time of <100 fs, a fall time of <5 ps, and a 235 fJ switching energy at 2.5 V bias, where the applied voltage reduces the switching energy by ∼16×. This technique paves the way for the emergence of ultra-efficient all-optical graphene switches that will meet the energy demands of next-generation photonic computing systems, and it is a promising alternative to lossy plasmon-enhanced devices.

384-Gb/s/lane PAM8 Operation Using 76-GHz Bandwidth EA-DFB Laser at 50°C with 1.0-Vpp Swing over 2-km Transmission

Abstract: 384-Gb/s PAM8 operation of both BTB and 2-km were demonstrated by a lumped-electrode type EA-DFB laser with clear eye-openings. 4.6 dB extinction ratio with 1.0- Vpp and 9.8 dBm output power were obtained at 50°C. © 2022 The Author(s)