Fan-in/fan-out (FI/FO) device with low crosstalk is essential for weakly coupled short-reach optical interconnect based on multicore fibers (MCF), for which the laser-direct-writing (LDW) technique is one of the preferred fabrication schemes. In this paper, the influence of FI/FO crosstalk on short-reach intensity-modulation/direction-detection MCF optical interconnection is firstly evaluated, and the crosstalk related to different refractive-index profiles of waveguides and misalignment is analyzed for LDW-FI/FO devices. Then low-crosstalk compact LDW-FI/FO devices matching 8-core MCF are fabricated, adopting multiple-scan method for waveguides with a flat-top refractive-index profile and aberration correction method for precise alignment. Owing to the low crosstalk, 8×100-Gbps optical interconnection over 10-km MCF is experimentally demonstrated with only 0.5-dB penalty compared to 10-km G.652D single-mode fiber transmission. Simulation results indicate that the transmission reach can be further extended to over 40 km. The proposed prototype system with low crosstalk is promising for high-speed optical interconnection applications.

Weakly-coupled space division multiplexing (SDM) techniques based on multi-core fibers (MCF) have attracted great attention for the capacity enhancement of optical interconnect systems and networks. In this paper, we propose a novel directlaser-writing (DLW) core separator device and apply it in a reconfigurable optical add/drop multiplexer (ROADM) structure for two-dimensional SDM and wavelength division multiplexing (WDM) switching. The proposed core separator matching an 8-core MCF is fabricated. Then assisted with MCF rotators, independent adding and dropping functionalities for arbitrary core are experimentally demonstrated with slight power penalty for both core and wavelength dimensions. The influence of crosstalk for cascading core separators is also investigated and below 0.35-dB receiving sensitivity penalty is obtained when three cores are dropped one by one. The compact DLW core separators can reduce the complexity of SDM nodes and will be beneficial for high-speed optical interconnects.

Based on the angular velocity transformation matrix, the paper develops the differential motion equation BKTJBKdωIK/dt=BKTM for a planetary transmission, which is a linearly constrained system. Although the degrees-of-freedom of the system is varying during shift process, the angular velocity transformation matrix BK, whose entries are constans, is only related to engaged clutches and BK can be easily derived from a constant matrix BF by linear transformation. Based on this theory, a computer simulation program of dynamic analysis of a planetary transmission is written, which provides a perfect means for analysis of dynamic behaviour of a transmission at any shifting transients. As an illustration, that of an Allison-WT transmission from 3rd speed to 4th speed is simulated.

We propose a design of 3-dimensional integrated optical hybrid based on laser direct writing fabrication method for spatial-division-multiplexing transmission systems. Simulation shows that it can operate in the whole C-band with excess loss of 0.31-dB.