In this paper an on-chip device capable of wavelength-selective generation of vortex beams is demonstrated. The device is realized by integrating a spiral phase-plate onto a MEMS tunable Fabry-Perot filter. This vortex-MEMS filter, being capable of functioning simultaneously in wavelength and orbital angular momentum (OAM) domains at around 1550 nm, is considered as a compact, robust and cost-effective solution for simultaneous OAM- and WDM optical communications. Experimental spectra for azimuthal orders 1, 2 and 3 show OAM state purity >92% across 30 nm wavelength range. A demonstration of multi-channel transmission is carried out as a proof of concept.
In this work, we have used a tunable VCSEL for high-speed optical data transmission. To obtain wide tunability, a MEMS-DBR is surface micromachined onto a short-cavity high-speed VCSEL operating at 1550 nm. Ultra-wide continuous tuning is realized with electro-thermal actuation of the MEMS with built-in stress gradient
within SiOx/SiNy dielectric layers. The MEMS-VCSEL operates in single-mode with SMSR > 40 dB across the entire tuning range. Quasi-error-free transmission of direct-modulation at record 15 Gbps is reported for 20 nm tuning, showing the potential towards the standard requirements for the SFP+ modules in the tail-ends of the WDM transmission system.
As demand for higher bandwidth is drastically increasing, bandwidth efficiency is going to be an issue in Passive Optical Networks (PONs). Moreover, network operators plan to reduce the number of central offices (COs) while extending the reach of the optical links, this enables them to reduce the deployment costs. This paper demonstrates the advantages of advanced modulation formats and a suitable configuration for the power budget enhancement of hybrid Wavelength Division Multiplexing-Time Division Multiplexing-Passive Optical Networks (WDM-TDM-PONs). The proposed technique can offer higher data rate, better bandwidth efficiency, and large number of customers. Differential (Quadrature) Phase Shift Keying (DQPSK) signals and Orthogonal Frequency Division Multiplexing (OFDM) will be considered. Simulations are performed using different modulation formats to evaluate the behavior of the proposed PON extender. Finally, Transmission of 1 Tbps WDM/TDM-OFDMPON over 60 km optical link is presented here. The simulation results, prove that 1600 users can be covered with 40 Gbps peak data rate.
This paper experimentally investigates power budget extension configurations for WDM NG-PONs. Differential Phase Shift Keying (DPSK), and Differential Quadrature Phase Shift Keying (DQPSK) are considered. The budget enhancement techniques are based on Semiconductor Optical Amplifier (SOA). The paper thoroughly studies power budget enhancement for the two modulation formats and shows that the proposed configurations comply with current standards such as XG-PON1.