Low-crosstalk Switch Research Articles

Drive-noise-tolerant broadband silicon electro-optic switch

We report a broadband digital electro-optical switch, based upon a multi-stage Mach-Zehnder lattice design in silicon-on-insulator. A digital switching response is demonstrated, engineered through apodization of the coupling coefficients between stages. The digital switching behavior results in crosstalk lower than -15 dB for drive-voltage noise levels in excess of 300 mV(pp), which exceeds the noise tolerance of a conventional single-stage Mach-Zehnder switch by more than six-fold. In addition, the digital design enables a larger maximum 'on'-state extinction (below -26 dB) and lower 'on'-state free-carrier-induced insertion loss (less than 0.45 dB) than that of the single-stage switch. The noise-tolerant, low-crosstalk switch can thus play a key role within CMOS-integrated reconfigurable optical networks operating under noisy on-chip conditions.

Low crosstalk switch unit for dense piezoelectric sensor networks

Structural health monitoring (SHM), on the basis of piezoelectric (PZT) sensors and lamb wave method, is efficient in estimating the state of monitored structures. Furthermore, to monitor large-scale structures, dense piezoelectric sensor networks are required, which usually contain many piezoelectric sensor pairs called actuator-sensor channels. In that case, considering the few data acquisition channels especially in the data acquisition board with a high sampling rate and limited quantity of signal amplifiers used in an integrated computer system, a switch unit is adopted to switch to different channels. Because of the high frequency and power of the lamb wave excitation signal, there exists a crosstalk signal in the switch unit. A large crosstalk signal is mixed into the response signal so that the on/off-line signal processing task is difficult to achieve. This paper first analyzes the crosstalk signal phenomenon, describes its production mechanism, and proposes a method to reduce it. Then a 24-switch channel low crosstalk switch unit based on a digital I/O board PCI7248 produced by Adlink technology is developed. An experiment is implemented to validate it. Its low crosstalk characteristics make it promote the real application of the SHM based active lamb wave method. Finally, a general software program based on LabVIEW software platform is developed to control this switch unit.

Polarization-Independent Low-Crosstalk Operation of InAlGaAs–InAlAs Mach–Zehnder Interferometer-Type Photonic Switch With Hybrid Waveguide Structure

In this letter, we demonstrated a Mach-Zehnder interferometer-type photonic switch using multimode interference (MMI) couplers with InAlGaAs-InAlAs compound semiconductor materials. A hybrid-waveguide structure with different etching depths was adopted for MMI couplers and other parts of the waveguides for polarization-independent operation. As a result, low-crosstalk switching operation of less than -20 dB was confirmed regardless of polarizations of an input light. Switching currents were, respectively, 5.25 and 4.75 mA for TE and TM modes of the input light. High-speed switching operation with about 3-ns transition time was also confirmed.

Reconfigurable wavelength add-drop filtering based on a Banyan network topology and ferroelectric liquid crystal fiber-optic switches

This paper presents a modular optical implementation of a Banyan network by using the physical flexibility of the optical fiber to form the interconnections between compact switching stages based on bulk polarization optics. Specifically, these switching stages use total internal reflection (TIR) prisms with ferroelectric liquid crystal (FLC) polarization rotators to form compact modules. Using this Banyan network implementation, a reconfigurable multiwavelength add-drop filter for wavelength division multiplexed (WDM) applications is proposed. Experimental results for our fiber connected 2 in-2 out FLC-based bulk-optic switching stage gives a /spl sim/6.7 dB optical insertion loss and a /spl sim/-40 dB optical interchannel crosstalk level. A low 2 dB optical insertion loss design number is expected with optimized components, realizing high (e.g., 35 /spl mu/s) switching speed and low crosstalk switching networks.

Simultaneous and independent switching of 8-wavelength channels with 2-nm spacing using a wavelength-dilated acoustooptic switch

We have used a wavelength-dilated acoustooptic cross-connect, for independent routing of 8-wavelength channels separated by 2 nm. The individual acoustooptic switches making up this cross-connect provide low-crosstalk switching only for channel spacings of at least 4 nm. Total loss through the dilated 2/spl times/2 crossconnect is 9 dB, and crosstalk ranges from -25 to -35 dB. Switch architectures of this kind will be needed in multiwavelength networks where channel spacings are too close to be accommodated by a single multiwavelength switch.

Lossless and low crosstalk 4 × 4 optical switch array

AbstractThe optical switch array is a key device for realizing photonic switching systems. A lossless and low crosstalk switch is the most desirable component of large‐scale switching systems which have more than 100 input/output ports. to realize such a switch monolithically, a carrier‐injection‐type optical single‐slip structure (S3) switch with traveling‐wave amplifier (COSTA) have been proposed. to realize the COSTA, a carrier‐injection‐type optical switch and an optical amplifier that are suitable for integration have been developed. First, a carrier‐injection‐type optical switch where the PN junction was formed by crystal growth was fabricated. It was confirmed that the characteristics of the device do not deteriorate during heating, which makes it suitable for integration. Next, the structure of an optical amplifier which can be integrated into the optical waveguide using the reactive ion etching (RIE) process was investigated. an optical amplifier that was integrated into a straight optical waveguide was fabricated, and it was confirmed that this amplifier could produce enough gain (internal gain of 25 dB) to compensate for the loss in the optical switch. Using these two basic techniques, a 4 × 4 COSTA was fabricated. With this 4 × 4 COSTA, fiber‐to‐fiber lossless (maximum gain of 5 dB) and extremely low crosstalk characteristics (ON‐OFF ratio of 54 dB) were demonstrated.

A coherent photonic wavelength-division switching system for broad-band networks

A coherent photonic wavelength-division (WD) switching system, utilizing a coherent wavelength switch ( lambda switch), is proposed. In the proposed coherent lambda switch, the tunable wavelength filter function is accomplished using coherent optical detection with a wavelength tunable local oscillator. The coherent photonic WD switching system has the following features; (1) low crosstalk switching for dense WDM signal, and (2) large line capacity capability. Design considerations show that 32 wavelength division channels can be available with a coherent lambda switch. It is also shown that a broadband metropolitan-area-network with over 1000 line capacity is possible, using a multistage connection in the coherent lambda switches. The switching function of the coherent lambda switch is demonstrated in a two-channel wavelength-synchronized switching experiment, using 8-GHz-spaced, 280-Mb/s optical FSK signals.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>