All-Optical Logic Gate for XOR Operation Between 40-Gbaud QPSK Tributaries in an Ultra-Short Silicon Nanowire

Abstract

We demonstrate an all-optical XOR logic gate for 40-Gbaud quadrature phaseshift keying (QPSK) tributaries in a silicon nanowire for the first time. The XOR logic operation is realized based on four-wave mixing (FWM) in the C-band. Experimental results show negligible power penalty at a bit error ratio (BER) of 10 À6 compared with the back-toback signals. The BER floor appears at BER of 10 À6 for both I and Q tributaries of the logic operation, and the main reasons are the optical signal-to-noise ratio (OSNR) deterioration caused by nonlinear loss due to free carrier absorption (FCA) and two-photon absorption (TPA) and the cross-phase modulation (XPM)-induced phase impairments.

Ultra-Sensitive Intensity Modulated Strain Sensor by Tapered Thin-Core Fiber Based Modal Interferometer

“…According to Equation ( 5), the applied axial strain in fact can be magnified due to the reduced diameter of the taper waist. In theory, similar to the schemes reported in [24][25][26], the corresponding wavelength shift should be larger than that in an un-tapered structure. In our structure, under a suitable waist diameter, we experimentally prove that the energy loss of an evanescent wave field is very sensitive to the variation of the waist diameter caused by the increased or decreased axial strain.…”

“…Liu et al prepared a hybrid silica-polymer fiber sensor to gain the sensitivity of 28 pm/µε under an ultrahigh pressure condition [23]. In addition, Ruan and Yin respectively fabricated the bubble based micro-cavity interferometers through precise arc-discharge control, and the strain sensitivities were further increased to more than 30 pm/µε [24,25]. Moreover, the highest sensitivity so far reached 1.15 nm/µε in the range of 0~230 µε, through a cascaded micro-cavity structure [26].…”

Sensitivity-Enhanced Extrinsic Fabry–Perot Interferometric Fiber-Optic Microcavity Strain Sensor

“…The inline FP interferometric strain sensors can be realized in many different ways. These types of sensors can be classified into two types: the intrinsic FP interferometric (IFPI) strain sensors [24], and the extrinsic FP interferometric (EFPI) strain sensors [25,26,27,28,29,30]. The EFPI strain sensors have lower sensitivities to temperature and are insensitive to transverse strain.…”

“…An EFPI strain sensor can be fabricated by splicing a short silica capillary [25] or a hollow-core photonic crystal fiber [26] between two standard fibers. The EFPI strain sensing can also be achieved by the spherical [27], elliptical [28,29], or rectangular [30] micro-air bubbles generated on the axis of an optical fiber. Compared to FBG, LPFG, and MZ interferometric strain sensors, EFPI strain sensors are more easily fabricated, and most importantly, they exhibit far less strain–temperature cross-sensitivity.…”

All-Optical Half Adder Based on a 2x2 Multimode Interference Coupler

“…However, the present signal processing speed based on optical-to-electrical and electrical-to-optical conversions do not match the requirements of the future optical networks and wavelength division multiplexed systems because it is limited to the low speed of electrical logic circuits. In recent years, there are some works reported on alloptical logic circuits which can satisfy the requirements of high signal speed processing, wideband to avoid cumbersome optical-electrical-optical conversions [1]- [4]. But, a few reported works suffer from some fundamental limitations such as big size, low bandwidth and high loss.…”