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We numerically investigate the effects of a minute femtosecond pulse seed on continuous wave pumped supercontinuum generation when the frequency shift of the seed varies.
Because of its high transmission rate, Time and Wavelength Division Multiplexed Passive Optical Network (TWDM-PON) has become a particular research topic. Due to the wavelength flexibility and multiple user's access, it becomes necessary and imperative to consider the fairness between all the Optical Network Units (ONUs) so that we can improve the quality of service of the users. This fairness includes...
We designed and optimized a high-speed, low-loss electrodes applied to photodiode array (PDA) using simulating software HFSS. Optimized and un-optimized electrodes were fabricated and tested. A 1.1dB reduce of the insertion loss at 40GHz was achieved by the optimization. Meanwhile, photodiode array implementing the optimized electrodes has a 6.6GHz higher 3dB-bandwidth comparing to the photodiode...
This paper presents TRx modules based on microwave photonics developed by Tsinghua University and their application in ISAR. The Tx module is based on OAWG, and can produce signal with arbitrary waveforms on the demand with its frequency tuneable from GHz to 100GHz. its bandwidth up to 10GHz, and its maximum duration up to the order of millisecond. The Rx is a coherent frond end with its central frequency...
An echelle diffraction grating (de)multiplexer with arc-shaped grating teeth, based on a multi-guide vertical integration platform in InP is presented. The device can be applied to the 100GBASE-LR4 Ethernet systems, the crosstalk is better than −19 dB. By adjusting grating facets, the 3-dB spectral bandwidth is increased to 2.2 nm compared with 1.7 nm in a conventional design with a loss penalty less...
With the development of passive optical networks (PONs), to cache videos on optical network units (ONUs) is now considering as an efficient scheme for better-quality video service provision. In this paper, we study the problem of collaborative video distribution among ONUs under the limited storage capacity of each ONU with the aim to maximize the video hit ratio of ONUs (VHRO). Two scenarios will...
We propose a scheme for fast random number generation with a bandwidth-enhanced chaotic signal generated by injecting the signal of a traditional chaotic external-cavity semiconductor laser (ECSL) into a spectrum expansion module (SE). Our simulation results show that the bandwidth-enhanced chaotic can be generated and its efficient bandwidth can be greatly enhanced up to 70 GHz. Random bits in our...
We report a broadband ytterbium-doped femtosecond fiber laser around 980nm. The cavity is based on the all-normal dispersion (ANDi) configuration, including a diffraction-grating which plays a crucial role as a narrow-band spectral filter. The spectral bandwidth of mode-locked pulse reaches 11.4 nm, which approaches the gain bandwidth (about 13nm) of the ytterbium doped fiber around 980 nm. The pulse...
In this paper, a novel Cross-layer Dynamic Bandwidth Allocation Algorithm Based on Convex Optimization Theory(CO-CDBA) in Digital Video Broadcast-Return Channel via Satellite system is proposed. A novel utility function by taking application layer, Data Link Layer and physical layer(PHY) parameters into account is established. The Dynamic Bandwidth Allocation(DBA) problem is converted to a convex...
A broadband and tunable absorber with nearly zero static power consumption is proposed based on non-volatile floating-gate graphene structure. Such absorber has almost no static power consumption benefited from the non-volatile design. In such design, the central graphene can capture the tunneled electrons under the positive applied voltage, but cannot release these electrons after removing the voltage...
A security-enhanced chaos communication scheme by expanding and compressing the spectrum of modulated chaotic carrier is proposed, in virtue of a spectrum expansion module composed of two phase modulators and two dispersion mediums. The numerical results demonstrate that the efficient bandwidth of modulated chaotic carrier can be expanded up to several tens of GHz and the RF spectrum is uniformly...
The cognitive radio (CR) have been proposed to improve spectral efficiency and to meet growing demands for higher data rates in mobile communications and satellite communications. In this paper, we propose a blind estimation algorithm for a secondary user to estimate transmission parameters of the primary signal in an OFDM overlay system, using only the available fast Fourier transform (FFT) component...
In this paper, we studied the effect of mushroom-mesa structure on vertical incidence PIN photodiodes based on theory and experiments. A novel mushroom-mesa vertical incidence photodiode was fabricated. The 20-um-diameter mushroom-mesa photodiode with a 0.5-um absorption layer achieved a 3dB bandwidth of 24.1 GHz, which increased 39.3% compared with PIN photodiodes.
This paper proposes a novel fiber ring laser utilizing taper-coupled double-microsphere-cavities (TC-DMC) to stabilize its single-longitudinal-mode operating with a 0.01 nm narrow bandwidth. Fundamental properties including whispery gallery mode (WGM) mode distribution and transmission spectra in the DMC are investigated both theoretically and experimentally. Due to Vernier effect, the WGM spectrum...
Novel technologies based on pulse amplitude modulation (PAM) are studied for a high-speed visible light communication (VLC) system. In this paper, we summarize the latest progress on high-speed PAM-VLC systems including phase shifted Manchester coding, Nyquist filter, weighted pre-equalization, multi-band access, and hybrid time-frequency domain equalization, which supporting VLC high data-rate and...
In this paper, the high-speed modified uni-traveling-carrier photodiode (MUTC-PD) was designed and fabricatedfor low reverse bias. The 3-dB bandwidth and responsivity of MUTC-PD with 24-μm mesa diameter at 1-V reverse bias is 22.5 GHz and 0.22 A/W at the wavelength of1550 nm, respectively. The dark current of the device is less than 4nA at 3.3 V reverse bias. The fabricated device can achieve high...
Using Ethernet in fronthaul can achieve statistical multiplexing gains based on the new function split. When TWDM-PON is used in Ethernet based fronthaul network, the large granularity of bandwidth requirements and the diversified service types will lead to the bandwidth fragmentation in OLT pooling. To solve this challenge, we develop a mathematical model by establishing the 0–1 relationship matrix...
A service-aware dynamic bandwidth allocation with CoMP is proposed in the heterogeneous 5G fronthaul network. Simulation results show that the throughput and delay performance of users have been improved, and the QoS for high priority users can be guaranteed preferentially.
In Elastic Optical Net-works (EONs), dynamic allocation and release of lightpaths will lead to frequency spectrum fragment issue which making the optical spectrum into non-aligned, isolated and small-sized spectrum segments. Defragmentation strategies are key issues to minimize this problem. In this paper, we investigate the states of spectrum when the bandwidth blocking probability (BBP) is high,...
A mode conversion-based crosstalk-aware routing, spectrum and mode assignment (MC-CA RSMA) algorithm is introduced in space-division multiplexing elastic optical networks (SDM-EONs) over few-mode fibers. Simulation results show the MC-CA RSMA algorithm can greatly reduce the impact of inter-mode crosstalk on network performance compared with benchmark algorithms.
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