Km Of Standard Fiber Research Articles

Chip-Based Measurement-Device-Independent Quantum Key Distribution Using Integrated Silicon Photonic Systems

Photonic chip integration would greatly benefit quantum key distribution (QKD) systems for secure communication, in terms of compactness, scalability, and well-established fabrication techniques. This study demonstrates proof of concept for an all-chip measurement-device-independent QKD system using integrated silicon photonic technology. The prototype generates a key rate per pulse of $2.923\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ over a distance corresponding to 50 km of standard fiber with 25% detection efficiency; the system is projected to be able to work at 120 km with 85% detection efficiency. This technology shows great promise for highly integrated quantum communication networks.

Simple and high-speed polarization-based QKD

We present a simplified BB84 protocol with only three quantum states and one decoy-state level. We implement this scheme using the polarization degree of freedom at telecom wavelength. Only one pulsed laser is used in order to reduce possible side-channel attacks. The repetition rate of 625 MHz and the achieved secret bit rate of 23 bps over 200 km of standard fiber are the actual state of the art.

Architecture to integrate multiple PONs with long reach DWDM backhaul

This paper demonstrates the feasibility of an architecture that consolidates a number of deployed Passive Optical Network (PON) infrastructures into a long-reach, high-split ratio system which further increases equipment sharing between users. The demonstrated system allows the use of uncooled lasers with possible wavelength drift across a CWDM band (20 nm) with optical amplification and narrow optical filtering with no performance degradation. A complete study of potential implementations was performed with experimental results showing that a target performance of 10-10 could be achieved over 120 km of standard fiber with transmitter wavelengths from 1542 to 1558 nm and DWDM backhaul wavelengths from 1520 to 1535 nm. This gives the potential to support up to 2560 users.

CWDM Transmission in the S/C/L Bands over Standard Fibers with Total Capacity of 40 Gb/s

We present simulations of a 16 channels coarse wavelength division multiplexing (CWDM) system operating at 2.5 Gb/s transmitted over 55 Km of standard fiber. The channel space was optimized in order to improve the use of the operation spectrum and to avoid the water peak. The results demonstrate the feasibility of 40 Gbit/s total capacity CWDM system operation using the S, C and L bands with BER better than 10-9.

Multichannel dispersion compensation using a silicon waveguide-based optical phase conjugator

We experimentally demonstrate dispersion compensation using a silicon-based optical phase conjugator. We achieve simultaneous transmission of four dense wavelength division multiplexing (DWDM) channels spaced at 100 GHz and operating at 10 Gbits/s over 320 km of standard fiber. The measured power penalty at bit error rate of 10(-9) is less than 0.3 dB.

Dispersion compensation by optical phase conjugation in silicon waveguide

The use of a silicon-waveguide-based optical phase conjugator at the mid-span of a fibre link for dispersion compensation is experimentally demonstrated, enabling transmission of optical data at up to 40 Gbit/s over 320 km of standard fibre with clear open eye diagrams at the receiver. In addition, the feasibility of dispersion compensation for multiple DWDM channels simultaneously is demostrated. A signal conversion efficiency of −10 dB is obtained with a pump intensity of 37.5 MW/cm2 in the waveguide.

Demonstration of a Fully Integrated 85-Gbit/s ETDM Receiver in a Transmission Experiment over 500 km of Standard Fiber

Demonstration of a Fully Integrated 85-Gbit/s ETDM Receiver in a Transmission Experiment over 500 km of Standard Fiber

40-Gb/s Widely Tunable Low-Drive-Voltage Electroabsorption-Modulated Transmitters

We present the first 40-Gb/s widely tunable electroabsorption modulator (EAM)-based transmitters. The sampled-grating Distributed Bragg Reflector (SG-DBR) laser/EAM devices were fabricated using a multiple-band-edge-quantum-well-intermixing (QWI) technique, which requires only simple blanket regrowth and avoids disruption of the axial waveguide. Devices were fabricated from two different multiple quantum well (MQW) active-region designs for direct comparison. The SG-DBR lasers demonstrated 30 nm of tuning with output powers up to 35 mW. The integrated QW EAMs provided 3-dB optical modulation bandwidths in the 35-39 GHz range, low-drive voltage (1.0-1.5 VPtoP), and low/negative-chirp operation. Bit-error-rate measurements at 40 Gb/s demonstrated 0.2-1.1 dB of power penalty for transmission through 2.3 km of standard fiber

Electroabsorption-modulated laser light-source module using selective area growth for 10 Gb/s transmission

In this work, a novel light source of strained InGaAsP/InGaAsP MQW EAM monolithically integrated with DFB laser is fabricated by ultra-low-pressure (22×102Pa) selective area growth (SAG) MOCVD technique. Superior device performances have been obtained, such as low threshold current of 19 mA, output light power of about 7 mW, and over 16 dB extinction ratio at 5 V applied voltage when coupled into a single mode fiber. Over 10 GHz 3 dB bandwidth in EAM part is developed with a driving voltage of 3 V. After the chip is packaged into a 7-pin butterfly compact module, 10-Gb/s NRZ transmission experiments are successfully performed in standard fiber. A clearly-open eye diagram is achieved in the module output with over 8.3 dB dynamic extinction ratio. Power penalty less than 1.5 dB has been obtained after transmission through 53.3 km of standard fiber, which demonstrates that high-speed, low chirp EAM/DFB integrated light source can be obtained by ultra-low-pressure (22×10\+2Pa) SAG method.

Monolithic integration of electroabsorption modulator and DFB laser for 10-Gb/s transmission

A strained InGaAsP-InP multiple-quantum-well DFB laser monolithically integrated with electroabsorption modulator by ultra-low-pressure (22mbar) selective-area-growth is presented. The integrated chip exhibits superior characteristics, such as low threshold current of 19mA, single-mode operation around 1550nm range with side-mode suppression ratio over 40dB, and larger than 16dB extinction ratio when coupled into a single-mode fiber. More than 10GHz modulation bandwidth is also achieved. After packaged in a compact module, the device successfully performs 10-Gb/s NRZ transmission experiments through 53.3km of standard fiber with 8.7dB dynamic extinction ratio. A receiver sensitivity of −18.9dBm at bit-error-rate of 10−10 is confirmed.

Demonstration of Widely Tunable Single-Chip 10-Gb/s Laser–Modulators Using Multiple-Bandgap InGaAsP Quantum-Well Intermixing

High-speed wavelength-agile laser-modulators were fabricated for the first time using a quantum-well intermixing processing platform for monolithic integration. Over 19-GHz 3-dB modulator bandwidth was achieved and 10-Gb/s error-free transmission was demonstrated through 75 km of standard fiber.

Quantum key distribution over 30 km of standard fiber using energy-time entangled photon pairs: a comparison of two chromatic dispersion reduction methods

We present a full implementation of a quantum key distribution system using energy-time entangled photon pairs over a 30 km standard telecom fiber quantum channel. Two bases of two orthogonal states are implemented and the set-up is shown to be robust to environmental constraints such as temperature variation. Two different ways to manage chromatic dispersion in the quantum channel are discussed.

10-Gb/s All-Optical 2R Regeneration Using an MQW Fabry–PÉrot Saturable Absorber and a Nonlinear Fiber

An all-optical 2R regenerator that consists of an ion implanted InGaAsP multiple-quantum-well saturable absorber, a nonlinear fiber, and an optical filter is presented. Error-free 10-Gb/s transmission over 7000 km of standard fiber with an amplifier spacing of 80 km is demonstrated in a recirculating loop experiment.

Single sideband optical signal generation and chromatic dispersion compensation using digital filters

It is shown that signal processing for single sideband signal generation and electronic chromatic dispersion compensation can be implemented using low complexity digital filters. Effective compensation for the dispersion of up to 1700 km of standard fibre at 10 Gbit/s with 6-bit 20 GSa/s digital sampling was demonstrated.

Dispersion compensation in an optical communications system with an electroabsorption modulated laser and a fiber grating

The robustness of an optical communications system with an electroabsorption modulated laser (EML) to dispersion mismatch is investigated, where a fiber grating is used for dispersion compensation. We use 12-nm bandwidth 1360-ps/nm dispersion fiber gratings, which were fabricated to match the dispersion of 80 km of standard fiber, and an EML transmitter in a 10-Gb/s communications system testbed. We demonstrate a maximum power penalty <2 dB over a wide range of standard fiber lengths (30-110 km).

All-optical passive 2R regeneration for N×40 Gbit/s WDM transmission using NOLM and novel filtering technique

We propose an all-optical passive 2R regeneration method for WDM ( N×40 Gbit/s) dispersion-managed RZ transmission based on specially designed WDM guiding filters and in-line nonlinear optical loop mirrors. By system optimisation, the feasibility of 150 GHz-spaced × l6 channel transmission over 25,000 km of standard fibre is numerically demonstrated.

Electroabsorption modulated laser for long transmission spans

Strain-compensated AlGaInAs quantum-well electroabsorption modulated lasers (EMLs) transmit at 10 Gbits/s on uncompensated transmission spans of >75 km of standard fiber and >225 km of MetroCor fiber. Details of the design, fabrication, and testing are presented. A complex-coupled distributed feedback (DFB) grating is used to enable high output power. The epitaxy and chip structure are described. The paper studies what is needed to accomplish long-span transmission in terms of minimum physical requirements for laser mode control, facet reflection, index grating strength, laser-modulator matching, laser-modulator electrical isolation, modulator extinction ratio, modulator capacitance, linewidth enhancement factor, etc. The interaction of the modulator with the laser is analyzed and a requirement for this structure is computed for the electrical isolation resistance between modulator and laser contacts. Stability of the laser source is discussed and a method is derived for determining the grating's gain-coupling coefficient at operating power. Chirp due to the modulator is analyzed. Nonzero chirp of the modulator is shown to have beneficial impact on the quality of the signal after transmission. The effect of a bias-dependent alpha parameter is analyzed. Because bit-error rate is a strong function of mean alpha parameter and not a strong function of the range of alpha during nonreturn-to-zero modulation, we determine that tuning the chirp of the EML modulator to suit different fiber types (MetroCor, SMF-28, etc.) is practical. Specific tradeoffs are also required. Experimental results verify the analysis.

Fully stabilized electroabsorption-modulated tunable DBR laser transmitter for long-haul optical communications

We report on a fully functional 2.5-Gb/s electroabsorption (EA)-modulated wavelength-selectable laser module meeting all long-haul transmission requirements for stability, chirp, power and linewidth over 20 channels on a 50-GHz grid. Based on a highly integrated InP chip comprising a distributed Bragg reflector (DBR) laser, semiconductor optical amplifier, power monitor, and EA-modulator, the compact transmitter module also contains optics and control circuits necessary to ensure simultaneous long-term wavelength and mode stability. We have achieved 2.5-Gb/s transmission on all 20 channels over 680 km of standard fiber.

A comparative study of the performance of seven- and 63-chip optical code-division multiple-access encoders and decoders based on superstructured fiber Bragg gratings

We report a range of elementary optical coding and decoding experiments employing superstructured fiber Bragg grating (SSFBG) components: first, we perform a comparative study of the relative merits of bipolar and unipolar coding: decoding schemes and show that the SSFBG approach allows high-quality unipolar and bipolar coding. A performance close to that-theoretically predicted for seven-chip, 160-Gchip/s M-sequence codes is obtained. Second, we report the fabrication and performance of 63-chip, 160-Gchip/s, bipolar Gold sequence grating pairs. These codes are at least eight times longer than those generated by any other scheme based on fiber grating technology so far reported. Last, we describe a range of transmission system experiments for both the seven- and 63-bit bipolar grating pairs. Error-free performance is obtained over transmission distances of /spl sim/25 km of standard fiber. In addition, we have demonstrated error-free performance under multiuser operation (two simultaneous users). Our results highlight the precision and flexibility of our particular grating writing process and show that SSFBG technology represents a promising technology not just for optical code division multiple access (OCDMA) but also for an extended range of other pulse-shaping optical processing applications.

A supercontinuum source based on an electroabsorption-modulated laser for long distance DWDM transmission

We describe a 40-channel X 9.953 Gbit/s dense wavelength-division multiplexed (DWDM) transmitter based on spectrum-slicing of supercontinuum light generated from an electroabsorption-modulated laser (EML). Error-free transmission of all channels over 544 km of standard fiber is demonstrated.