K. Takiguchi

Integrated-optic encoder/decoder for time-spreading/wavelength-hopping optical CDMA

We demonstrate an integrated-optic encoder/decoder for time-spreading/wavelength-hopping optical code division multiple access. It is composed of a wavelength multi/demultiplexer and variable delay lines fabricated by using silica-based planar lightwave circuit technology. We evaluated the device characteristics, including those of the key components and the encoding/decoding operation, and confirmed its flexible code assignment ability and good auto/cross correlations. We then tested the performance of the encoder/decoder by undertaking bit error rate measurements with 10-Gb/s pseudorandom binary sequence signals and confirmed its applicability to optical layer multicast routing and its ability to compensate for bit skew caused by fiber chromatic dispersion.

Integrated-optic dispersion slope equalizer for N/spl times/ several tens of Gb/s WDM transmission

We report a dispersion slope equalizer on a planar lightwave circuit for wavelength division multiplexing (WDM) transmission. This device consists of an array of lattice-formed equalizers with different compensation values fabricated on one wafer and arrayed-waveguide gratings for wavelength multi/demultiplexing. We describe its configuration, operational principle, parameter design, fabrication, and measured characteristics in detail. N/spl times/20 and N/spl times/40 Gb/s slope equalizers were fabricated and their characteristics agreed well with designed values. We also report a reduction in the bias electrical power needed for thermooptic phase shifters in the equalizer array that we realized by employing a phase trimming technique normally used for optical switches.

Optical-signal-processing device based on waveguide-type variable delay lines and optical gates

In this paper, an optical-signal-processing device mainly designed for time-slot switching is demonstrated. The device is composed of variable delay-line arrays fabricated by planar lightwave circuit technology and high-speed optical gates. The variable delay-line arrays consist of transversal-form or lattice-form optical circuits. The operating principle is based on serial-to-parallel conversion, adjustment of the delay time between the parallel signals, and the gating of the optical bits or packets in the optical region. The device does not require any interaction between lightwaves through optical nonlinear effects or filter banks for code matching. As an example of its operation, label-processing functions are demonstrated, specifically the label swapping of optical return-to-zero pulses. The merits of the proposed device are described and problems that must be solved are also discussed.

Low-loss integrated-optic dynamic chromatic dispersion compensators using lattice-form planar lightwave circuits

We propose novel techniques for measuring lattice-form PLCs without monitor waveguides. We employed them to develop polarization-insensitive dynamic dispersion compensators with a dispersion variability of -150 /spl sim/ +150 ps/nm and a low loss of 4.2 dB for 50 GHz-bandwidth.

AWG-Based Wavelength Router With Nonuniform Number of Transmission Paths

We have developed an arrayed-waveguide-grating (AWG)-based wavelength router with unequal transmission bandwidths for a system with nonuniformly distributed traffic. To realize the router, we designed the aperture width of the input-output waveguides at the border of the slab waveguide. We applied this AWG router to a physical star and logical full-mesh wavelength routing system, and we could create different numbers of paths between the nodes to correspond to the traffic demand

Optical pulse pattern recognition circuit based on an optical digital-to-analog converter on a planar lightwave circuit

A 4-bit optical digital-to-analog converter for use in optical pulse pattern recognition has been fabricated on a silica-based planar light-wave circuit. We successfully confirmed the recognition of various kinds of 4-bit pulse sequence at 10 Gb/s.

Integrated-optic timing tuner for high-speed WDM signals

We demonstrate an integrated-optic timing tuner, which is used for the fine adjustment of wavelength-division-multiplexing (WDM) signal delays. This tuner can be utilized to compensate for the bit skew of high-speed WDM bit-parallel links in the next generation or to reduce nonlinear effects in WDM transmissions. The tuner consists of an arrayed-waveguide grating and variable delay lines comprising asymmetrical Mach-Zehnder interferometers with different arm lengths. We demonstrate experimentally that our device is capable of accurate delay tuning for 16 /spl times/ 10 to 40-Gb/s systems.

Integrated photonic decoder with complementary code processing and balanced detection for two-dimensional OCDMA

We propose a novel integrated-photonic decoder for two-dimensional (time/wavelength) OCDMA, which processes complementary codes and utilizes balanced detection to reduce unwanted cross-correlation interference. We successfully carried out a 10 Gbit/s transmission that demonstrated its effectiveness.

Time-spreading/wavelength-hopping OCDMA using PLC encoder/decoder with large spread factor

We fabricated an integrated-optic encoder/decoder with a spread factor of 48 for time-spreading/wavelength-hopping optical CDMA (the largest number reported for this CDMA). We successfully carried out a 2.5 Gbit/s transmission with plural users using the devices

Excitation engineered pulse train generators

Excitation-engineered pulse train repetition rate multipliers fabricated as a planar lightwave circuit are investigated. The overall temporal response is shown to be influenced by the design of both the splitter and combining regions.