A novel all-optical switch: the wavelength recognizing switch

A new class of an all-optical switch-the wavelength recognizing switch is proposed and experimentally demonstrated. The device uses a control signal to sense the wavelength of the input packet and taps a portion of the data packet to the appropriate output port. The device is based on noncollinear four-wave mixing in a broad-area traveling-wave semiconductor optical amplifier. Measured switching efficiency is +8.2 dB with -28.8 dB of crosstalk. The recognition bandwidth is as narrow as 0.03 /spl Aring/ and the 3-dB switching bandwidth is 42 nm.     

Highly efficient four-wave mixing in an optical fiber with intensity dependent phase matching

Wavelength conversion via four-wave mixing in an optical fiber is investigated under a pump intensity dependent phase-matching condition. To obtain a high conversion gain, we use a fiber with a small mode-field diameter (4.2 /spl mu/m) and a small dispersion slope (0.0307 ps/km/nm/sup 2/). When the signal wavelength is set so that it is 9.2 nm longer than the zero-dispersion wavelength of the fiber, we obtain a wavelength conversion gain of greater than 5 dB over a pump wavelength region of more than 8 nm.     

Widely tunable wavelength converter using a double-ring fiber laser with a semiconductor optical amplifier

Widely tunable wavelength conversion has been demonstrated using broad-band orthogonal-pump four-wave mixing in a semiconductor optical amplifier placed at the intersection of two fiber ring lasers. The all-optical wavelength converter operates without using any external pump source. A 3-dB conversion-range over 40 nm is obtained. The measured power penalty is 1.5 dB for a 2.5-Gb/s converted signal at 10/sup -9/ bit error rate.     

A novel 1×4 coupler-multiplexer permutation switch for WDMapplications

A novel 1×4 coupler multiplexer permutation switch (CMPS) is proposed for applications in wavelength-division-multiplexing (WDM) optical networks. The structure of the CMPS integrates the multiplexing and switching functions into a single compact device. It consists of a single-mode/multimode-waveguide grating-assisted, backward-coupler multiplexer followed by a 1×4 digital optical switch (DOS). The specific design uses an InP-based 1×4 CMPS with InGaAsP-InP multiple-quantum-well (MQW) DOS. The calculated values of crosstalk for the coupler multiplexer and the DOS are <-25 dB and -23 dB, respectively, giving an overall crosstalk <-21 dB for channel bandwidths of 10-13 GHz. The device channels are unequally spaced, which reduces unwanted four-wave mixing (FWM), but are fitted to the ITU standard wavelength grid     

Polarization-insensitive InP-based MQW digital optical switch

A polarization-insensitive InP-based p-i-n multiple-quantum-well switch is demonstrated for the first time. Polarization-insensitive switching and loss are achieved. Crosstalk and loss measurements across a wavelength range of 20 nm centered at 1.55 μm are reported. A crosstalk of better than -13 dB is achieved for both TE and TM polarizations across the 1.54-1.56-μm wavelength range with a switching voltage of -7 V. A low on-chip loss of less than 3 dB is achieved for both TE and TM across the above wavelength range, with a compact switch structure which is 3 mm long     

All-optical wavelength translation over 80 nm at 2.5 Gb/s usingfour-wave mixing in a semiconductor optical amplifier

Wavelength conversion using conventional single pump four-wave mixing in semiconductor optical amplifiers is limited to wavelength shifts of a few tens of nanometers due to the decrease of signal-to-noise ratio with wavelength shift. In this letter, we demonstrate an 80-mn wavelength shift with four-wave mixing (FWRW) using two orthogonally polarized pumps. The power penalty at a 10^-9 bit-error rate for a 2.5-Gb/s signal is less than 1.0 dB. This result demonstrates the large wavelength shift capacity of this (FWM) technique     

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

An 8×8 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     

Pump-wavelength dependence of FWM performance in semiconductor optical amplifiers

We report on experimental investigation of the dependence on pump-wavelength of efficiency and signal to background ratio of a wavelength converter based on four-wave mixing in a semiconductor optical amplifier (SOA). The signal wavelength has been varied over a 60-nm range at fixed signal-converted detuning. Both efficiency and background level increase by moving the operation wavelength toward bandgap. Nevertheless, we observe a variation of the signal to background ratio of only 2 dB in a 40-nm range. A qualitative interpretation of the results is presented.     

All-optical wavelength shifting of microwave subcarriers by using four-wave mixing in a semiconductor optical amplifier

We demonstrate all-optical wavelength shifting over 9 nm for two microwave subcarriers by using four-wave mixing in a semiconductor optical amplifier. In our experiment, the RF spectrum is relatively unaffected by wavelength shifting and the resultant system power penalty is /spl sim/0.5 dB. Such a transparent wavelength shifter may be a critical component in WDM networks supporting both subcarrier multiplexed (SCM) and high speed digital transmission.     

A stable optical comb with double-Brillouin-frequency spacing assisted by multiple four-wave mixing processes

A stable optical comb with a double-Brillouin-frequency spacing, employing a 2.5-km common single mode fiber (SMF) is proposed and demonstrated experimentally. The simultaneous existence of the first-order and third-order Stokes within the ring cavity excites the higher-order Stokes and anti-Stokes via multiple four-wave mixing (FWM) processes. Ten odd-order Stokes, nine odd-order anti-Stokes and a second-order Stokes signal with a wavelength spacing of 0.172 nm (∼20 GHz) are simultaneously achieved at a Brillouin pump (BP) level of 160 mW. The maximum power fluctuation of the proposed optical comb is less than 1 dB at room temperature within 100 min. The optical comb can show a good stability and flexibility in the choice of operating wavelength.     

Demonstration of bufferless optical packet switch with recursive stages of parametric wavelength converter

We demonstrate in an experiment an optical packet switching (OPS) using recursive parametric wavelength converters (PWCs) which uses the combination of two or more PWCs for wavelength conversions. The PWCs, which are based on four-wave mixing in highly nonlinear fibers, are possible for multiple wavelength conversion, allowing a share-per-node switching scheme, and thus significantly reducing the number of wavelength converters. Detailed demonstration of a developed OPS prototype using the joint of two PWCs indicates the generation of various wavelength conversion patterns which play an important role for OPS performance. The converted signals after two stages of PWC are obtained with error-free operations and low power penalties (BER=10^?9) of about 2.0 dB. Numerical results also show significant improvement in packet blocking probability by the proposed recursive PWC-based OPS in comparison with the previous non-recursive schemes.     

Wavelength add-drop switching using tilting micromirrors

This paper describes a single-mode optical fiber switch which routes individual signals into and out of a wavelength multiplexed data stream without interrupting the remaining channels. The switch uses free-space optical wavelength multiplexing and a column of micromechanical tilt-mirrors to switch 16 channels at 200 GHz spacing from 1531 to 1556 nm. The electrostatically actuated tilt mirrors use an 80 V peak-to-peak 300 KHz sinusoidal drive signal to switch between ±10° with a 20 μs response. The total fiber-to-fiber insertion loss for the packaged switch is 5 dB for the passed signals and 8 dB for added and dropped signals, with 0.2 dB polarization dependence. Switching contrast was 30 dB or more for all 16 channels and all input and output states. We demonstrate operation by switching 622 Mb/s data on eight wavelength channels between the two input and output ports with negligible eye closure     

Active optical pulse compression with a gain of 29.0 dB by usingfour-wave mixing in an optical fiber

The four-wave mixing gain in an optical fiber strongly depends on the nonlinear phase mismatch when the pump power itself causes a nonlinear index change. The peak of the pump pulse has a much higher gain than its wings, and so this process can be used to obtain efficient pulse compression. A 93-ps signal pulse at 1569.9 nm is compressed to as short as 20 ps with a gain of 29.0 dB. The wavelength-converted signal at 1559.9 nm is simultaneously compressed to 21 ps and amplified by 28.9 dB as compared with the original signal     

Multifunctional photonic switching operation of 1500 nm Y-coupledcavity laser (YCCL) with 28 nm tuning capability

The authors present new results on extended electrical tuning, fast spatial switching, and optically controlled wavelength conversion characteristics for the recently developed InP-based Y-laser structure. The devices have a 80 nm thick bulk InGaAsP active layer and are completely grown by metalorganic vapor phase epitaxy. The facets at both ends of the chip are as-cleaved without antireflective coating. The addressable range for electrically controlled wavelength switching was extended to the record value of 28 nm. When operated as a lossless 1:2 optical space switch, fiber-to-fiber gain >0 dB, extinction ratio >50 dB and high speed operation up to 1 Gb/s were shown. Optically triggered tunable wavelength conversion including dynamic operation was also demonstrated     

Study of polarization-insensitive wave mixing in bulk semiconductoroptical amplifiers

A detailed experimental investigation of polarization-insensitive dual-pump wave mixing in bulk, polarization-insensitive semiconductor optical amplifier (SOA) is reported. Measurements of the phase conjugated, polarization-insensitive four-wave mixing (FWM) efficiency are reported versus: (1) pump-signal wavelength spacing while keeping the wavelength spacing between the two orthogonally polarized pumps constant and (2) wavelength spacing between the pumps while keeping the signal wavelength constant. The achieved wavelength conversion bandwidth of the polarization-insensitive scheme is approximately 60 nm with efficiency between 8 and -20 dB. The obtained results are in good agreement with theoretical predictions     

Widely tunable polarization-independent all-optical wavelengthconverter using a semiconductor optical amplifier

We report a polarization-independent widely tunable four-wave mixing wavelength converter using polarization diversity and broad-band orthogonal pumps in a single semiconductor optical amplifier. The conversion efficiency is nearly constant (less than 3-dB variation) over a 36-nm range with less than 0.34 dB polarization sensitivity. The power penalty at 10^-9 bit error rate for a 10-Gb/s signal is less than 0.9 dB     

Wide-band polarization-free wavelength conversion based on four-wave-mixing in semiconductor optical amplifiers

Wide-band polarization free wavelength conversion based on four-wave mixing in semiconductor optical amplifiers (SOAs) subject to two pump beams has been studied in detail. With equalized forward and backward pump power, polarization independence of the converted signal was experimentally achieved when the wavelength detuning was larger than 1.24 nm. This is independent of the SOA bias current. When the wavelength detuning between the signal and one pump beam was fixed at 1.6 nm, the amplitude of the converted signal was nearly constant over a 58-nm wavelength range. A new theoretical analysis allows for signals of arbitrary polarization state to be considered. The experimental results are in good agreement with the theory developed here.     

Cascaded wavelength conversion by four-wave mixing in a strained semiconductor optical amplifier at 10 Gb/s

We demonstrate for the first time cascaded wavelength conversion by four-wave mixing in a semiconductor optical amplifier. Bit-error-rate performance of <10/sup -9/ at 10 Gb/s is achieved for two conversions of up to 9 nm down and up in wavelength. For two wavelength conversions of 5 nm down and up, a power penalty of 1.3 dB is measured. A system of two wavelength converters spanning 40 km of single-mode fiber is also demonstrated.     

OPSnet: design and demonstration of an asynchronous high-speed optical packet switch

This paper presents the results of the optical packet switched network (OPSnet) project, which investigated the design of an asynchronous optical packet switch suitable for the core of an optical transport network (OTN). The requirements for the switch were to control and route variable-length packets transmitted at bit rates beyond 100 Gbit/s. The subsystems and techniques used are analyzed and presented. Fast header encoding and passive decoding is based on the differential phase-shift keying (DPSK) method. The dual-pump four-wave mixing (d-p FWM) wavelength-conversion technique, in combination with an arrayed waveguide grating (AWG), is utilized for packet switching. An advanced and fully controllable mechanism for the packet-switch control is presented, which is implemented on field programmable gate array (FPGA) technology. The control wavelength is generated using a tunable laser, the actual wavelength and new header values are provided utilizing fast header recognition and look-up tables. The integration of the subsystems is discussed, and the results of a four-output port asynchronous packet-switch demonstrator operating at 40 Gbit/s are presented. Finally, the switch limitations are examined and design issues are discussed.     

An InGaAs/GaAs MQW optical switch based on field-induced waveguides

A novel optical waveguide switch containing InGaAs/GaAs multiple-quantum wells (MQW) is proposed. In this structure, a large field-induced refractive index increase (0.1%) due to the quantum-confined Stark effect (QCSE) is utilized to generate electrically controllable waveguides. Switching operation of a first fabricated device has been investigated at wavelengths of about 1 μm. A crosstalk ratio of -18.8 dB and an extinction ratio of 20.9 dB was achieved at a reverse voltage of -7 V. Within an operational wavelength region of 9 nm, crosstalk was found to be less than -13 dB for both switching conditions. Further, the proposed switch structure seems to be well suited for monolithic integration with laser diodes and exhibits the potential for high-speed operation