106.25-Gbps PAM-4 bidirectional optical sub-assembly module with in-line arrangement of optical and electrical interfaces.

We successfully demonstrate a 106.25-Gbps PAM-4 bidirectional optical sub-assembly for optical access networks, including a driver amplifier and an electro-absorption modulated laser for a transmitter, a photodiode and transimpedance amplifier for a receiver, and an optical filter block. For its implementation, we propose design strategies providing an in-line arrangement of optical and electrical interfaces while ensuring optical alignment tolerance for easy assembly and reducing electrical crosstalk between the transmitter and receiver. Measured receiver sensitivity was <-11.4 dBm for the KP4 forward error correction limit during transmitter operation, and measured power penalty of 10-km single-mode fiber transmission was <0.9 dB.

53 GBd PAM-4 fully-integrated silicon photonics transmitter with a hybrid flip-chip bonded laser.

We present a fully-integrated single-lane 53 GBd PAM-4 silicon photonics (SiPh) transmitter (Tx) with a flip-chip bonded laser diode (LD). The LD is butt-coupled to a Si edge coupler including a SiO2 suspended spot-size converter. The coupled power exceeds 10 dBm with a 1 dB allowable misalignment of 2.3 µm. The RF and eye performances of the Tx are evaluated. Extinction ratio >5 dB is obtained at 3.5 Vppd voltage swing. Aided by silicon capacitors, the Tx decouples parasitic inductances leading to remarkable improvements in the eye openings and transmitter dispersion eye closure quaternary by 1.16 dB. By implementing the fully-integrated Tx with driver packaging, we successfully demonstrate 106 Gb/s real-time operation satisfying KP4-FEC threshold at -5 dBm receiver sensitivity.

Verification of hybrid-integrated 400-Gb/s (4 × 100 Gb/s) CWDM4 ROSA using a bandwidth-improved multilayer board.

We have successfully demonstrated a hybrid-integrated 400-Gb/s (4 × 100 Gb/s) CWDM4 PAM-4 receiver optical sub-assembly (ROSA) with a bandwidth-improved multilayer evaluation board. The proposed ROSA offers packaging simplification through passive optical alignment assembly of main components. In addition, we have proposed a structure to mitigate the bandwidth limitation issue caused by the typical edge connector mounting on the multilayer board, when needed bandwidth exceeds ∼20 GHz. With the bandwidth-improved multilayer board, the 3-dB bandwidth of the ROSA was observed to be >35.7 GHz and its receiver sensitivity was successfully measured to be <-10 dBm at FEC limit, bit error rate of 2.4e-4, for all channels.

Low-cost and miniaturized 100-Gb/s (2 × 50 Gb/s) PAM-4 TO-packaged ROSA for data center networks.

We design and implement a cost-effective and compact 100-Gb/s (2 × 50 Gb/s) PAM-4 receiver optical sub-assembly (ROSA) by using a TO-can package instead of an expensive box-type package. It consists of an optical demultiplexer, two PIN-PDs and a 2-channel linear transimpedance amplifier. The components are passively aligned and assembled using alignment marks engraved on each part. With a real-time PAM-4 DSP chip, we measured the back-to-back receiver sensitivities of the 100-Gb/s ROSA based on TO-56 to be less than -13.2 dBm for both channels at a bit error rate of 2.4e-4. The crosstalk penalty due to the adjacent channel interference was observed around 0.1 dB.

Highly alignment tolerant and high-sensitivity 100Gb/s (4 × 25Gb/s) APD-ROSA with a thin-film filter-based de-multiplexer.

We investigate and demonstrate a 100-Gb/s (4x25-Gb/s) receiver optical sub-assembly (ROSA) based on avalanche photodiodes and a thin-film filter-based de-multiplexer. The overall alignment tolerances of the ROSA are relaxed to have larger than ± 25 µm by improving optical coupling structure. The receiver sensitivity of each lane is also measured to be less than -22.2 dBm, a record minimum to our knowledge, at the bit error ratio of 10-12 for 25.78-Gb/s NRZ signal.

Analysis of dimensional tolerance for an optical demultiplexer of a highly alignment tolerant 4 × 25 Gb/s ROSA module.

We have developed a 4 × 25 Gb/s ROSA (receiver optical sub-assembly) module for 100G Ethernet optical transceiver. This ROSA module has very large alignment tolerance of more than ± 250 µm between the optical DMUX (demultiplexer) and four photodiodes, for the reason it has the advantage of being easily assembled. The large alignment tolerance can be attributed to the dimensional tolerant optical DMUX, which is composed of four thin film filters attached to a parallelogram-shaped optic block. Since it is important to define the fabrication specifications for the dimension of the optic block, we analyze dimensional tolerance for the optic block using three-dimensional simulation. This parallelogram-shaped optical DMUX permits length tolerance of ± 300 µm and angular tolerance of ± 0.1°. The fabricated optical DMUX is estimated to have the angular error of less than 0.09°.

Variant achalasia, the hole of the original classification.

BACKGROUND/AIMS: High-resolution manometry (HRM) is a useful tool for classifying esophageal motility disorders. However, there remain findings that cannot be classified in clinical fields. Recently, an updated classification system was announced. The purpose of this study was to evaluate whether originally unclassifiable groups can now be classified according to the updated Chicago Classification system. MATERIALS AND METHODS: We reviewed the results of HRM studies performed from January 2008 to December 2010 on 150 consecutive patients (75 men, age 17-76) referred to the Gospel Hospital manometry laboratory for evaluation. We found originally unclassified results and re-categorized them according to the updated Chicago Classification system. RESULTS: Thirty-seven of 150 patients were originally unclassified cases. Patients from the unclassified and classified groups had similar distributions of age and sex. All unclassified patients were re-diagnosed as having variant achalasia according to the updated Chicago Classification system. CONCLUSION: The updated Chicago Classification can categorize originally unclassified groups of esophageal motility disorder.