Adolfo Lerín

Direct Phase Modulation DFBs for Cost-Effective ONU Transmitter in udWDM PONs

A technique for direct phase modulating a low-cost distributed feedback laser is presented for user transmitter in ultra dense wavelength division multiplexing passive optical networks. It consists of a simple RC network, which equalizes the phase response. The method is tested with differential phase-shift keying modulation and heterodyne coherent detection at 1.25 and 2.5 Gb/s showing a penalty <;1 dB at BER = 10-3 compared with external phase modulation.

Simplified Polarization Diversity Heterodyne Receiver for 1.25Gb/s Cost-Effective udWDM-PON

We propose a heterodyne receiver with a single-photodiode per polarization for ONU receiver in low-cost udWDM-PON. This grants polarization diversity operation showing a penalty of 6dB in sensitivity compared to a balanced detector.

Polarization independent single-PD coherent ONU receiver with centralized scrambling in udWDM-PONs

A centralized polarization scrambling and single-PD coherent ONU Rx system is proposed and tested with two Tx and direct-phase modulated DFBs. Polarization independence at the Rx, and a sensitivity at BER=10-3 of ×45dBm with 7.5GHz channel spacing were achieved.

DFB laser reallocation by thermal wavelength control for statistical udWDM in PONs

We demonstrate a simple fast method of laser wavelength channel switching for the wavelength management of UDWDM-PONs where the ONUs have source wavelengths with random distribution and are controlled with limited thermal tunability.

1Gbps full-duplex links for ultra-dense-WDM 6.25GHz frequency slots in optical metro-access networks

1 Gbps full-duplex optical links for 6.25 GHz ultra dense WDM frequency slots are demonstrated and optimized for cost-effective metro-access networks. The OLT-ONU downlinks are based on 1 Gbps Nyquist-DPSK using MZM and single-detector heterodyne reception obtaining a sensitivity of -52 dBm. The ONU-OLT uplinks are based on 1 Gbps NRZ-DPSK by directly phase modulated DFB and also single-detector heterodyne reception obtaining same sensitivity of -52 dBm. The power budget of full-duplex link is 43 dB. These proposed links can provide service to 16 (32) users at each 100 (200) GHz WDM channel.

DQPSK Directly Phase Modulated DFB for Flexible Coherent UDWDM-PONs

A bandwidth-limited distributed feedback laser directly phase modulated with a 5-Gb/s differential quadrature phase shift keying (DQPSK) signal is demonstrated in a statistical ultra-dense wavelength division multiplexing passive optical network. Optical DQPSK modulation was achieved by simply equalizing a four-level waveform. An intradyne receiver based on a 120° optical hybrid with straightforward differential decoding processing was used to detect and recover the data attaining a sensitivity of -38 dBm at {BER}=10-3 . Negligible penalty was observed when adding a second user at 5-GHz channel separation.

Exploiting RSOA for Uplink Transmission with Coherent Detection for Low Cost UDWDM-PON

Upstream phase modulation exploiting low cost reflective semiconductor optical amplifier (RSOA) at ONU is applied for simplified coherent detection through DFBs as local lasers at ONU and at OLT.

6.25Gb/s differential duobinary transmission in 2GHz BW limited direct phase modulated DFB for udWDM-PONs

A differential duobinary codification is proposed for directly phase modulating a 2 GHz BW equalized DFB laser. The method was tested with homodyne coherent detection achieving 6.25 Gb/s bitrate transmission with -38.5 dBm Rx sensitivity at BER=10-3.

Survey of Faster-Than-Nyquist for Flexible Passive Optical Networks

The constant growing in traffic demands has driven to look for new methods with which to reduce the occupied bandwidth and efficient use of the optical spectrum. Despite non-orthogonal signalling lead to intersymbolic interference introduction, it can be considered as a promising solution if interference is introduced in a controlled manner. In this paper the modulation scheme called Faster-Than-Nyquist (FTN) is presented for Flexible Passive Optical Networks application. Different ratios of bandwidth reduction vs. power penalty are presented and compared to the Nyquist modulation.

Flexible D(Q)PSK 1.25–5 Gb/s UDWDM-PON with directly modulated DFBs and centralized polarization scrambling

A 6.25GHz spaced UDWDM PON is experimentally tested with directly-phase modulated lasers, polarization scrambling and homodyne detection. Bitrates from 1.25Gb/s to 5Gb/s per λ are achieved in a 50km fibre-link serving up to 1024 users.