Mach-Zehnder Interferometer Switch Research Articles

Comparison of interferometric all-optical switches for demultiplexing applications in high-speed OTDM systems

We have investigated three interferometric all-optical switches based on cross-phase modulation (XPM) in semiconductor optical amplifiers (SOAs), the semiconductor laser amplifier in a loop mirror (SLALOM) switch, the Mach-Zehnder interferometer (MZI) switch, and the ultrafast nonlinear interferometer (UNI) switch. Switching windows with different widths are measured under similar conditions for all three switching configurations. We introduce the integrated contrast ratio (ICR) as a measure to evaluate the performance of a switch from switching windows. Using the ICR, the switches are compared and their application is discussed as demultiplexer in optical time division multiplexing (OTDM) systems for data rates of 40, 80, and 160 Gb/s.

Ultrafast switching dynamics of Mach-Zehnder interferometer switches

We present results of cross-gain and cross-phase modulation experiments on InGaAsP-based semiconductor optical amplifiers and Mach-Zehnder interferometer (MZI) switches. For 150-fs input pulses, we observe strong spectral and pulse shape distortions of the signal pulse, especially in the pulse overlap regime. These pulse deteriorations are induced by subpicosecond gain and refractive index nonlinearities. In consequence, the ON-OFF ratio of the MZI switch is drastically reduced for subpicosecond switching windows. In the copropagation arrangement, the switching window with maximum transmission is shown to be limited to about 1.5 ps.

Low loss and high extinction ratio strictly nonblocking 16×16 thermooptic matrix switch on 6-in wafer using silica-based planar lightwave circuit technology

We describe a silica-based 16/spl times/16 strictly nonblocking thermooptic matrix switch with a low loss and a high extinction ratio. This matrix switch, which employs a double Mach-Zehnder interferometer (MZI) switching unit and a matrix arrangement to reduce the total waveguide length, is fabricated with 0.75% refractive index difference waveguides on a 6-in silicon wafer using silica-based planar lightwave circuit (PLC) technology. We obtained an average insertion loss of 6.6 dB and an average extinction ratio of 53 dB in the worst polarization case. The operating wavelength bandwidth completely covers the gain band of practical erbium-doped fiber amplifiers (EDFAs). The total power consumption needed for operation is reduced to 17 W by employing a phase-trimming technique which eliminates the phase-error in the interferometer switching unit.

Chopped InGaAs/InP quantum wells for a polarization-independent space switch at 1.53 μm

We realized a polarization-independent Mach–Zehnder interferometric switch at 1.53 μ m using chopped quantum wells. The calculated electroabsorption and electrorefraction agree well with experiment. The window for polarization-independent switching within 0.1 V is 12 nm. A phase shifting section of 1.7 mm yields a <1dB electroabsorption unbalance and a 6 V switching voltage.

A chopped quantum-well polarization-independent interferometric switch at 1.53 /spl mu/m

We have theoretically designed and realized a phase shifter for a low-loss Mach-Zehnder interferometric switch. The phase shifter is based on 0.85% tensile strained InGaAs-InP chopped quantum-well material. We realized a Mach-Zehnder interferometric switch with polarization-independent switching voltages as low as 3.3/spl plusmn/0.05 V at 1525 nm for a switch with a 4-mm-long phase shifting section. The wavelength sensitivity of the switch is 0.036 V/nm for TE and 0.053 V/nm for TM polarization. Calculations of the electro-refraction in the -0.85% strained chopped quantum-well (QW) material based on the 4/spl times/4 Luttinger-Kohn Hamiltonian show that the electro-refraction due to the quantum-confined Stark effect (QCSE) for TM polarization is equal to the sum of the mutually comparable QCSE electro-refraction and the Pockels effect for TE polarization in waveguides along the [11~0] axis. Our first-principle model for calculating the electro refraction is an accurate design tool for predicting device performance in complicated layer structures. The shortest possible phase shifter with a <-25 dB crosstalk penalty due to electro-absorption unbalance can be as short as 2.2 mm. This compact switch is predicted to have a 6-V switching voltage and a 15-nm window for polarization-independent switching with a <-25-dB crosstalk penalty. With a slight increase of the strain, this chopped QW material can be used for polarization independent switching around 1550 nm.

Ultrafast all-optical multiple quantum well integrated optic switch

An all-optical integrated Mach-Zehnder interferometer switch is implemented using selective area disordering of a multiple quantum well structure. Ultrafast all-optical switching with an adjustable switching window ranging from 2 to 100 ps is demonstrated. The switch contrast ratio in this preliminary device is measured to be 9 dB.

Polarization independent dilated WDM cross-connect on InP

A four wavelength 2/spl times/2 optical wavelength-division-multiplexed cross-connect with dilated switches is reported. The device is monolithically integrated on InP and consist of two eight-channel PHASAR's combined with 16 electrooptic Mach-Zehnder interferometer switches. On-chip loss is less than -17 dB and crosstalk is better than -20 dB.

High-extinction ratio and low-loss silica-based 8×8 strictly nonblocking thermooptic matrix switch

This paper describes a silica-based 8/spl times/8 strictly nonblocking thermooptic matrix switch with a high-extinction ratio and low loss. We realized this matrix switch by using a configuration which combines a double Mach-Zehnder interferometer (MZI) switching unit and an N/spl times/N matrix arrangement thus reducing the total waveguide length. The 8/spl times/8 matrix switch was fabricated on a 4-in wafer using planar lightwave circuit technology. We obtained an average extinction ratio of 60.3 dB and an average insertion loss of 5.1 dB. The operating wavelength bandwidth completely covers the gain band of practical erbium-doped fiber amplifiers (EDFAs).

Silica-based 8×8 optical matrix switch integrating new switching units with large fabrication tolerance

An 8/spl times/8 optical matrix switch consisting of asymmetric Mach-Zehnder (MZ) interferometer switching units with a waveguide intersection was fabricated using silica-based planar lightwave circuits (PLC's) on a silicon substrate. This switching unit can realize a high extinction ratio and a wide operation wavelength range even if the coupling ratios of the directional couplers (DC's) consisting the switching unit, deviate greatly from the ideal value of 50%. A matrix switch with a DC-coupling ratio of 30% was fabricated to test the validity of the proposed geometry. The average insertion loss was 7.3 dB in the transverse electric (TE) mode and 7.5 dB in the transverse magnetic (TM) mode. The average extinction ratio was 31.2 dB in the TE mode and 31.3 dB in the TM mode. The wavelength range with an extinction ratio greater than 20 dB was over 100 nm.

Low-loss and high-extinction-ratio silica-based strictly nonblocking 16/spl times/16 thermooptic matrix switch

A low-loss and high-extinction-ratio silica-based 16/spl times/16 thermooptic matrix switch is demonstrated. The switch, which employs a double Mach-Zehnder interferometer switching unit and a matrix arrangement which reduces the total waveguide length, is fabricated with 0.75% refractive index difference waveguides on a 6-in silicon wafer. The average insertion loss and the average extinction ratio are 6.6 and 55 dB, respectively. The total power consumption is 17 W.

Thermooptic interferometric switches fabricated by electron beam irradiation of silica-on-silicon

The thermal stability of channel optical waveguide devices fabricated by electron beam irradiation of plasma-enhanced chemical vapor deposition (PECVD) silica-on-silicon is investigated. The degree of stability is dependent on the starting material and on the use of thermal annealing prior to irradiation. High-temperature postprocessing is shown to reduce modal confinement, increasing losses in waveguide bends and the coupling coefficient in directional couplers. A low-temperature cladding process based on a thick MgF/sub 2/ layer is described, and low-loss thermooptic Mach-Zehnder interferometric switches are demonstrated.

High-input-power saturation properties of a polarization-insensitive semiconductor Mach-Zehnder interferometer gate switch for WDM applications

We propose that a polarization-insensitive Mach-Zehnder interferometer (MZI) switch is useful for optical gate elements, especially if multiwavelength signals are input. This device has high-input-power saturation properties, which shows that both the operating voltage and the extinction ratio do not change when the optical input power reaches at least +18 dBm. A high extinction ratio of 30 dB was achieved in the wide-wavelength range of 20 nm. Moreover, the extinction ratio can be improved by up to 45 dB by using a cascaded configuration to decrease crosstalk. These results indicate the MZI gate switch is well suited to wavelength-division multiplexing (WDM) network components.

High-extinction ratio and low-loss silica-based 8/spl times/8 thermooptic matrix switch

A high-extinction ratio and low-loss silica-based 8/spl times/8 thermooptic matrix switch is demonstrated. The 8/spl times/8 matrix switch is realized by using a double Mach-Zehnder interferometer switching unit and a matrix arrangement which reduces the total waveguide length. The average extinction ratio and the average insertion loss are 60.3 and 5.2 dB, respectively.

2×2 Mach–Zehnder interferometric switch based on hetero-n-i-p-i quantum wells

A 2×2 Mach–Zehnder interferometric switch has been developed employing 3 dB multimode interference (MMI) couplers and laterally contacted hetero-n-i-p-i quantum wells as the active material providing refractive index changes. Switching over a 4π range between the cross state and the bar state with an on/off ratio of 17:1 has been observed. A record voltage-length product for switching is observed of less than 1 V mm. By exploiting the quadratic nature of the quantum confined Stark effect, a differential switching voltage as low as 0.2 V mm is observed in the push–pull configuration.

Singlemode optical switches based on SOI waveguides with large cross-section

The realisation of a thermo-optical Mach-Zehnder interferometer switch based on SOI (silicon-on-insulator) material is reported. At a wavelength of 1.3 µm, on-off ratios of 13 dB (TE) aud 9 dB (TM) are achieved with a switching power of 150 mW. The measured rise time is 5 µs.

Integrated optical switches in silicon based on SiGe-waveguides

The realization of switches in silicon base on monomode Ge-indiffused SiGe waveguides is reported. At a wavelength of 1.3 mu m a Mach-Zehnder interferometer switch with a modulation depth of -10 dB at a current of 150 mA is obtained. This is the lowest value reported so far for single-mode optical switches in silicon.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Three-space representation of phase-mismatch switching in coupled two-state optical systems

A three-space graphical representation for the operation of optical switch/modulators based on two-state systems is reviewed. This visual framework provides insight into the behavior of devices such as the waveguide directional coupler and Mach-Zehnder interferometric switches and combiners and the concept of delta-beta reversal. I is based on the covering map of the group SU(2) onto SO(3) and is analogous to the Poincare formulation for polarization. Because of its pictorial nature, this representation can serve as an aid in the conception of innovative device structures. A class of switches identified using this approach is described and demonstrated by experiment.

Integrated astable optical multivibrator using Mach-Zehnder interferometric optical switches

An integrated astable optical multivibrator has been analysed and demonstrated experimentally for the first time using a couple of Mach-Zehnder interferometric optical switches with crossed and straight electronic feedback. Fairly good agreement is found between experimental and analytical results.

Integrated bistable optical device using mach-zehnder interferometric optical waveguide

An integrated mirrorless bistable optical device based on the Mach-Zehnder interferometric optical switch has been proposed and demonstrated experimentally using a Ti: LiNbO3 waveguide. The resulting device is capable of combining more than two of them to realise multifunctional optical devices such as optical multivibrators.

Mach-Zehnder Interferometer

Beam propagation method (BPM) was used to study 2x2 Mach-Zehnder interferometer switch with electro-optical effects in titanium diffused lithium niobate based directional coupler was used to develop the design. This design is capable of de-multiplexing the wavelength1300nm. This project intends to design high performance NxN electro-optic switch. This optical device is widely used in optical network, especially in the optical link of fiber-to-the-home (FTTH). The design is carried out using BPM_CAD, which is a very powerful and user-friendly optics waveguides modeling method as it core element. Research on optical waveguide switching using directional coupler (DC) and Mach-Zehnder interferometer (MZI) has been going on and already created great interest among the researchers. There are different types of material being used in much different way apart from the most common electro-optic materials such as lithium niobate. Recently, the study was also confined to the use of silica on silicon technology considering that the cost of the technology. Other non-linear-optic materials such as polymers have been embedded into part of the silica waveguide.