Electroabsorption Modulator-integrated Laser Research Articles

EML based real-time 112 Gbit/s (2 × 56.25 Gbit/s) PAM-4 signal transmission in C-band over 80 km SSMF for inter DCI applications

Abstract We report on an electro-absorption modulator (EAM) integrated laser (EML) based real-time 112 Gbit/s (2 × 56.25 Gbit/s) 4-level pulse amplitude modulation (PAM-4) signal transmission in the C-band over 80 km of standard single-mode fiber (SSMF). Various operating conditions of the EAM were investigated to find the optimum driving conditions for PAM-4 modulation. When the EAM reverse bias was set to the inflection point of the transfer curve, which was −2.35 V, we obtained a bit error ratio (BER) of 4 × 10−8, which is well below the forward error correction (FEC) limit. The results demonstrate the feasibility of using EMLs for implementation in PAM-4 transceivers for inter-datacenter interconnection (inter-DCI) applications.

A cost-effective 25-Gb/s EML TOSA using all-in-one FPCB wiring and metal optical bench

We present a cost-effective 25-Gb/s electro-absorption modulator integrated laser (EML) transmitter optical sub-assembly (TOSA) using all-in-one flexible printed circuit board (FPCB) wiring and a metal optical bench (MOB). For a low cost and high bandwidth TOSA, internal and external wirings and feed-through of the TOSA to transmit radio-frequency (RF) signal are configured all-in-one using the FPCB. The FPCB is extended from an exterior of the TOSA package up to an EML chip inside the package through the slit formed on a rear sidewall of the package and die-bonded on the MOB. The EML TOSA shows a modulated output power of more than 3.5 dBm and a clear eye pattern with a dynamic extinction ratio of ~8.4 dB at a data rate of 25.78 Gb/s.

Performance Improvement of 40-Gb/s Electroabsorption Modulator Integrated Laser Module With Two Open-Circuit Stubs

In this letter, we propose and demonstrate a compact, low-cost, and easy to manufacture microstrip line with two open-circuit stubs to alleviate impedance mismatching of a packaged 40-Gb/s electroabsorption modulator integrated laser (EML) module. For comparison, two 1550-nm EML modules are fabricated, the only difference being that one of them is made with open-circuit stubs, while the other is not. It is revealed that the open-circuit stubs technique expands the 3-dB modulation bandwidth from 25.2 to 33.6 GHz, and the suppression of the input return loss below -10 dB in the range of the higher frequency of the sub-assembly with chip is also successfully demonstrated. Further evidence showing the advantage of the EML module with open-circuit stubs over the one without open-circuit stubs include the effective reduction in the RMS jitter of the eye diagram from 1.4 to 1.2 ps, as well as the improvement of the sensitivity, which changes from -8.3 to -9.5 dBm measured with the same receiver.

Impact of Electro-Absorption Modulator Integrated Laser on MB-OFDM Ultra-Wideband Signals Over Fiber Systems

This paper presents investigation of the impact of electro-absorption modulator integrated laser (EML) on performance of multiband-orthogonal frequency-division-multiplexing (MB-OFDM) ultra wideband (UWB) signal over single-mode fiber transmission by theoretical and experimental analysis, considering various parameters, such as fiber length, bias voltage, modulation power, bias current, and temperature of EML. The effect of the EML modulation nonlinearities on the OFDM subcarriers in MB-OFDM UWB over fiber system is investigated considering intermodulation distortion (IMD) and adjacent channel power ratio. It is shown that MB-OFDM UWB over fiber is limited by SNR for small modulation power and EML modulation nonlinearities induced IMD for high modulation power. Fiber transmission length is mainly degraded by EML phase noise converted relative intensity noise and power fading. The developed theory is verified by experiments.

40 Gb/s Traveling-Wave Electroabsorption Modulator-Integrated DFB Lasers Fabricated Using Selective Area Growth

In this paper, we present the fabrication of 40 Gb/s traveling-wave electroabsorption modulator-integrated laser (TW-EML) modules. A selective area growth method is first employed in 40 Gb/s EML fabrication to simultaneously provide active layers for lasers and modulators. The 3 dB bandwidth of a TW-EML module is measured to be 34 GHz, which is wider than that of a lumped EML module. The 40 Gb/s non-return-to-zero eye diagram shows clear openings with an average output power of +0.5 dBm.