Silica-based PLC Research Articles

Polarization-insensitive 90° optical hybrid using silica-based PLC.

A 90° optical hybrid (OH) based on a 4×4 multimode interference (MMI) coupler is characterized and analyzed using the silica-based planar light circuit. The OH is designed to be polarization-insensitive with an extremely low polarization-dependent loss (<0.18d B) and phase error (w i t h i n±1.3∘). The fabricated chip exhibits an excess loss of 3.4dB and 3.8dB for TE and TM polarizations at 1550nm. The measured phase error is w i t h i n±7.2∘ over 50nm in the C+L band with a polarization-dependent error w i t h i n±3.5∘. The fabrication tolerance of the MMI width and waveguide sidewall angle is analyzed, which can well explain the deviation from the theoretical calculation.

Novel research on reliability of silica-based PLC optical splitters

Environmental, mechanical and optical reliability are basic premises for application of PLC optical splitters. According to temperature and humidity cycling experiment, it demonstrated that insertion loss of PLC optical splitter varies with temperature. Compared to performance at room temperature, the maximum insertion loss change of device is 0.472 dB at 75 °C, and 0.486 dB at −40 °C. A three-dimensional finite element model of PLC chip coupled with fiber array was established to study the effects of temperature on insertion loss. The simulation results match experimental results, indicating that misalignment of PLC chip and fiber array is the main reason for insertion loss change. It is significant to consider the influences of global temperature rather than only paying attention to performance at static temperature when we evaluate the reliability of PLC optical splitters.

PLC-based LP_11 mode rotator for mode-division multiplexing transmission

A PLC-based LP11 mode rotator is proposed. The proposed mode rotator is composed of a waveguide with a trench that provides asymmetry of the waveguide. Numerical simulations show that converting LP11a (LP11b) mode to LP11b (LP11a) mode can be achieved with high conversion efficiency (more than 90%) and little polarization dependence over a wide wavelength range from 1450 nm to 1650 nm. In addition, we fabricate the proposed LP11 mode rotator using silica-based PLC. It is confirmed that the fabricated mode rotator can convert LP11a mode to LP11b mode over a wide wavelength range.

Design and Fabrication of Novel Symmetric Low-Loss 1 × 24 Optical Power Splitter

In this paper, a three-branch structure with different output widths, broadening, and transition waveguide are discussed in detail. Based on the three-branch structure, a compact, low-loss, and good uniformity 1 × 24 optical power splitter is designed and fabricated using silica-based PLC technology on quartz substrate. The measurement results show that the insertion loss, the uniformity, wavelength-dependence loss of the splitter are less than 14.8, 0.92, and 0.93 dB, respectively, in the wavelength range from 1.25 to 1.65 μm. The polarization dependence loss is less than 0.16 dB in the wavelength of 1.27, 1.31, 1.49, 1.55, and 1.625 μm.

A compact 1×64 optical power splitter using silica-based PLC on quartz substrate

Abstract In this paper, a compact and low wavelength-dependence loss (WDL) 1×64 optical power splitter is fabricated using silica-based PLC technology on quartz substrate. The cascaded Y-branch structures are optimized in detail, and a compact 1×64 optical power splitter layout is obtained. The measured results show that the insertion loss (IL), the uniformity and WDL of the best results of all splitters are less than 19.2 dB, 1.0 dB and 0.5 dB, respectively, in the wavelength range from 1.26 μm to 1.65 μm, and the total product ratio of Standard grade in a whole 6 in. wafer is more than 80%. The results imply that our technology completely satisfies the need of mass manufacture.

A compact and low-loss 1×8 optical power splitter using silica-based PLC on quartz substrate

In this paper, a compact, low-loss and good-uniformity 1×8 optical power splitter with new Y-branch structure is demonstrated using silica-based PLC technology on quartz substrate. Broadening waveguide and transition waveguide of the new Y-branch are optimized by using 3D BPM. The measurement results show that the insertion loss (IL) and the uniformity (UNIF) of the splitters are less than 9.5dB and 0.35dB, respectively, in the wavelength range from 1.26μm to 1.65μm, and the total product ratio of premium grade in a whole 6in. wafer is more than 95%. The results mean that our technology completely satisfies the need of mass manufacture.

Silica-based PLC with heterogeneously-integrated PDs for one-chip DP-QPSK receiver

To realize a DP-QPSK receiver PLC, we heterogeneously integrated eight high-speed PDs on a silica-based PLC platform with a PBS, 90-degree optical hybrids and a VOA. The use of a 2.5%-Δ waveguide reduced the receiver PLC size to 11 mm x 11 mm. We successfully demonstrated 32 Gbaud DP-QPSK signal demodulation with the receiver PLC.

Integrated 13/15 μm cyclic AWG router for λ-tunable WDM/TDM-PON

We propose a cyclic NxN AWG router that can multi/demultiplex upstream and downstream signals with different channel spacings in different wavelength regions. We fabricated a 4 x 4 AWG router for our novel λ-tunable WDM/TDM-PON using silica-based PLC technology and showed that it can cyclically multi/demultiplex both 20 nm-spaced and 200 GHz-spaced signals at 1.3 and 1.5 μm, respectively.

Asymmetric Half-Wave Plate Configuration of PLC Mach–Zehnder Interferometer for Polarization Insensitive DQPSK Demodulator

We propose a novel polarization dependent frequency shift (PDf) reduction method for fabricating a silica-based PLC DQPSK demodulator incorporating an asymmetrically positioned half-wave plate, and demonstrate error-free 43-Gbit/s demodulation for any incident SOP. The PDf has a detrimental effect on the demodulation performance of a DQPSK signal, and it is degraded by various kinds of PLC fabrication errors. In this paper, we focus on the polarization crosstalk in the coupler, which is one of the main causes of PDf. To eliminate such PDf, we controlled both the position of the half-wave plate in the MZI and the polarization of the propagated light. We describe the principle of this PDf reduction method in detail and provide a theoretical and experimental discussion. In addition, we describe a compact DQPSK demodulator composed of a single MZI based DQPSK demodulator with a 90-degree optical hybrid. This demodulator configuration can reduce the receiver's footprint. Finally we achieved a compact DQPSK demodulator with a low PDf of less than 0.10 GHz in the L-band.

Ultralow Power Consumption Silica-Based PLC-VOA/Switches

We have achieved a silica-based PLC thermooptic switch with a power consumption of only 30 mW without any deterioration in the optical properties by using a tapered narrow ridge structure. To reduce the power consumption further, we propose a novel structure, the suspended narrow ridge structure, which has the advantages of both the tapered narrow ridge structure and the already reported suspended-bridge structure. As a result, we achieved PLC-VOA/switches with excellent heat design flexibility and a power consumption of 20 mW. In addition, using the proposed the suspended narrow ridge structure, we demonstrate a 16-channel V-AWG with a compact size of 20 times 17 mm and a low total power consumption of 320 mW.

Dispersion resulting from wide passband shape in 50-GHz-spaced wavelength router

We report dispersions resulting from a slot device (SD) in silica-based arrayed-waveguide grating (AWG). A SD is used to produce flattened passbands and we show the dependence on the bandwidth, the crosstalk, the ripple, and the chromatic dispersion (CD) of the passband in the presence of such a device. A comparison with other known techniques is also given. The device has been developed on a high index silica-based PLC platform but can be implemented on higher index contrast platforms.

Filter-embedded wavelength-division multiplexer for hybrid-integrated transceiver based on silica-based PLC

A thin film filter-embedded wavelength-division multiplexer is designed for a hybrid-integrated WDM transceiver based on a silica-based PLC platform. A compact multiplexer with a low insertion loss of 1.1 dB and a low crosstalk of <-50 dB is successfully fabricated.

High reliability silica-based PLC 1×8 splitters on Si

The authors describe the reliability of silica-based PLC 1×8 splitters, which was investigated with reference to the Bellcore requirements. All of the 19 1×8 splitters that were tested satisfy the Bellcore optical criteria after 5000 h at 75 °C and 90% RH.