40 Gb/s PAM-4 transmitter IC for long-wavelength VCSEL links

Conventional 850 nm multimode fiber links deployed in warehouse-scale data centers will be limited by modal dispersion beyond 10 Gb/s when covering distances up to 1 km. This can be resolved by opting for a single-mode fiber (SMF), but typically requires the use of power-hungry edge-emitting lasers. We investigate the feasibility of a high-efficiency SMF link by reporting a 0.13 mu m SiGe BiCMOS laser diode driver optimized for long-wavelength vertical-cavity surface-emitting lasers (VCSELs). Bit-error rate experiments at 28 and 40 Gb/s up to 1 km of SMF reveal that four-level pulse amplitude modulation can compete with non-return-to-zero in terms of energy efficiency and scalability. With 9.4 pJ/b, the presented transmitter paves the way for VCSEL-based SMF links in data centers

High-speed PAM4-based Optical SDM Interconnects with Directly Modulated Long-wavelength VCSEL

This paper reports the demonstration of high-speed PAM-4 transmission using a 1.5-{\mu}m single-mode vertical cavity surface emitting laser (SM-VCSEL) over multicore fiber with 7 cores over different distances. We have successfully generated up to 70 Gbaud 4-level pulse amplitude modulation (PAM-4) signals with a VCSEL in optical back-to-back, and transmitted 50 Gbaud PAM-4 signals over both 1-km dispersion-uncompensated and 10-km dispersion-compensated in each core, enabling a total data throughput of 700 Gbps over the 7-core fiber. Moreover, 56 Gbaud PAM-4 over 1-km has also been shown, whereby unfortunately not all cores provide the required 3.8 $\times$ 10 $^{-3}$ bit error rate (BER) for the 7% overhead-hard decision forward error correction (7% OH HDFEC). The limited bandwidth of the VCSEL and the adverse chromatic dispersion of the fiber are suppressed with pre-equalization based on accurate end-to-end channel characterizations. With a digital post-equalization, BER performance below the 7% OH-HDFEC limit is achieved over all cores. The demonstrated results show a great potential to realize high-capacity and compact short-reach optical interconnects for data centers.Comment: 7 pages, accepted to publication in 'Journal of Lightwave Technology (JLT

Aerosol-jet printed interconnects for 2.5 D electronic and photonic integration

We demonstrate a flexible face-up 2.5 D packaging technique for a hybrid electro-photonic integration. The process is based on an aerosol-jet technology to print the high-speed electrical interconnects between electronic and photonic chips as a potential alternative for the traditional bonding wires. The technology is realized by creating a transparent mechanical polymer support to bridge the gap between the photonic and electronic chips and subsequently printing the electrical interconnects on top. First, the daisy-chain test chips were used to prove the functionality of the technology by printing the electrical interconnects between the test chips. Then, a standard 85 ° C/85 RH test was performed to investigate the reliability of the printed interconnects and no failure or degradation was observed over 700 h. Afterwards, the technology was successfully applied on functional chips. An optical transmitter based on vertical cavity surface emitting lasers (VCSELs) was demonstrated at 50 Gb/s by printing 200-μm-long high-speed silver interconnects between a 4-channel SiGe BiCMOS driver and four VCSELs. In addition, the technology showed the potential to interconnect silicon photonics chips. An assembly of an electro-absorption modulator (EAM) and a CMOS driver was successfully demonstrated. Clear open eye diagrams were obtained at 40, 50, and 56 Gb/s for the EAM-driver assembly even after 2 km of a standard single-mode fibe

Cardiovascular risk factors, anxiety symptoms and inflammation markers: Evidence of association from a cross-sectional study

Introduction Anxiety disorders and Cardiovascular (CV) diseases, among the most common disorders in Western World, are often comorbid. A chronic systemic inflammatory state might be a shared underlining pathophysiological mechanism. Aims To investigate the association between anxiety symptoms, CV risks factors and inflammatory markers in an outpatient sample. Methods Cross-sectional study. Inclusion criteria: outpatients aged ≥40 years, attending colonoscopy after positive faecal occult blood test, negative medical history for cancer. Collected data: blood pressure, glycaemia, lipid profile, waist circumference, BMI, PCR (C Reactive Protein), LPS (bacterial Lipopolysaccharide). Psychometric tests: HADS, TCI, IMSA, SF36. Statistical analysis performed with STATA13. Results Fifty four patients enrolled (27 males, 27 females). Sixteen patients (30.19%) were positive for anxiety symptoms. Thirty-three patients (61.11%) had hypertension, 14 (25.93%) hyperglycaemia and 64.81% were overweight, with frank obesity (BMI≥ 30) in 11 subjects (20.37%). Anxiety symptoms were associated with low hematic HDL values (OR = 0.01; P = 0.01) and high concentration of triglycerides (OR = 0.023; P = 0.02) at the multiple regression model. At the univariate logistic analysis, anxiety was associated with LPS (OR = 1.06; P = 0.04). Conclusions Further evidence over the epidemiological link between common mental disorders and CV diseases was collected, with possible hints on pathophysiology and causative mechanisms related to inflammation. The importance of screening for anxiety and depression in medical populations is confirmed. Suggestions on future availability of screening tools based on inflammatory-related indicators should be the focus of future research