Zhujun Wan

All-Optical Highly Sensitive Chromatic Dispersion Monitoring Method Utilizing Phase-Matched Four-Wave Mixing

This letter represents a highly sensitive all-optical chromatic dispersion (CD) monitoring method utilizing phase-matched four-wave mixing (FWM) in highly nonlinear optical fibers (HNLFs). The monitoring ability arises from the exponential FWM gain which provides an exponential power transfer function (PTF) mapping the CD experienced by the signals onto the average power of the output idler wave. Our method is simple and much more sensitive compared to the other PTF-based monitoring methods proposed before. The sensitivity enhancement is important for highly accurate dispersion compensation and makes the method effective for signals with high duty cycles. Furthermore, by tailoring the phase-matched wavelength range our method can be used to monitor CD in a wavelength-division-multiplexing (WDM) network.

Wavelength-Selective Switch Based on a Polarization-Independent Transmission Grating and a High Fill-Factor Micromirror Array

This letter presents a wavelength-selective switch (WSS) based on a polarization-independent transmission grating and a high fill-factor micromirror array. The WSS does not require additional polarization management devices and successfully achieves a low polarization-dependent loss (PDL). A 1 × 4 port WSS has been successfully demonstrated. The maximum driving voltage is about 155 V and an applied overvoltage also illustrates the good reliability of WSS. The test results show that the PDL is less than 0.4 dB. The measured fiber-to-fiber insertion loss (IL) is in range from about 6 to 7 dB and the switching time is about 530 μs .

Tolerance Analysis of Lattice-Form Optical Interleaver With Different Coupler Structures

A set of recursion equations is developed to synthesize a coherent two-port lattice-form optical delay-line circuit with different coupler structures. A fifth-order lattice-form optical interleaver is designed, and parameter tolerance is analyzed with crosstalk consideration. Results show that the phase tolerance of delay lines is six times the coupling-coefficient-angle tolerance of directional couplers. The coupling-coefficient-angle tolerance of directional couplers in an interleaver with stabilized couplers is improved by one order than that in an interleaver with simple directional couplers if global uniformity of the planar-lightwave-circuit process is supposed. The tolerance of an interleaver with cascaded multimode interference (MMI) couplers does not improve much, but an MMI coupler is more immune to process error than a directional coupler. Theoretical analysis meets the simulation results well. A stabilized coupler and a cascaded MMI coupler are both good substitutes for a simple directional coupler in lattice-form optical interleaver, and both help to reduce crosstalk

A novel routing optical matrix swtiching method

Abstract A routing optical matrix switching method which constitutes of a novel nonblocking routing optical Crossbar network system is presented. The routing optical Crossbar network includes two parts: one is a routing fan-out unit which provides multi-optical channels for each input light beam, and the other is a routing fan-in unit which combines the optical channels with the same destination output port into one. A module of 4×4 routing optical matrix switching module was developed by this method, which is as well applicable to 2×2,8×8, etc. These optical matrix switches can widely be used in the field of DWDM communications.

Design and fabrication of an optical interleaver with cascaded multimode interference couplers

A lattice-form optical interleaver was designed and fabricated with a silicon-based silica waveguide. Cascaded multimode interference couplers were first employed in the lattice circuit and helped to relax the fabrication tolerance. The device shows good performance, the insertion loss is less than 2.25 dB, the passband ripple is less than 0.15 dB, the cross talk is less than -18.9 dB, and the 0.5 dB passband is more than 100 GHz.

1×8 fiber-optic switch based on an innovative waveguide converter and a micro torsion mirror

This paper reports a 1x8 fiber-optic switch based on an innovative waveguide converter and a micro torsion mirror. A compact 9-fiber collimator is implemented with the waveguide converter. With the micro torsion mirror aligned to the 9-fiber collimator, light from the central fiber can be steered to any of the other 8 fibers. The introduction of the waveguide converter enables a smaller and faster micro torsion mirror. The switch shows good performance, insertion loss, nonuniformity, and cross talk is <3.02 dB, <0.4 dB, and <-35 dB respectively. Improvements of performance are expected after further optimization.

Optical MEMS devices based on micromachined torsion structure

Optical MEMS components with optical fiber inputs and outputs are the most important kinds of optical MEMS devices because of their applications in optical communication industry and fiber-optic sensors. Efficient optical coupling is the key to develop optical MEMS devices for optical communication and sensing, however, efficient coupling between MEMS actuators or sensing structures and optical fibers is a challenging job. Besides high performance MEMS actuators and coupling micro-optics are needed, the MEMS structures should adapt to coupling micro-optics. The torsion MEMS micro-mirrors and gratings can couple with fiber collimators at low insertion loss, therefore, the torsion MEMS structure is a good choice for optical MEMS devices, especially for continuous or multi-level controlled devices. In this paper, we report three kinds of optical MEMS devices based on silicon torsion micro structure, MEMS variable optical attenuator (VOA), 1×8 MEMS optical switch and high-speed MEMS torsion blazed grating , which have been developed recently in our optical MEMS research group. The three devices are coupled with optical fibers by optical fiber collimators, so low loss coupling can be achieved.

A two-in-one Faraday rotator mirror exempt of active optical alignment

A two-in-one Faraday rotator mirror was presented, which functions as two independent Faraday rotation mirrors with a single device. With the introduction of a reflection lens as substitution of the mirror in traditional structure, this device is characterized by exemption of active optical alignment for the designers and manufacturers of Faraday rotator mirrors. A sample was fabricated by passive mechanical assembly. The insertion loss was measured as 0.46 dB/0.50 dB for the two independent ports, respectively.

Bandwidth analysis of channelized tunable optical dispersion compensator based on liquid crystal on silicon

Channelized tunable optical dispersion compensators (CTODCs) based on spatial light modulators (SLMs) are considered as enabling devices for future all optical high speed dynamic networks. This paper analyzes the relationship between CTODC bandwidth and its compensation range. Analytic expressions for the coupling loss spectrum of CTODC based on liquid-crystal on silicon (LCOS) are presented. These expressions can be useful tools for the bandwidth estimation and design of CTODC based on LCOS. (2 pages)