Amy A. Au

An efficient all-fiber variable optical attenuator via acoustooptic mode coupling

A novel broad-band variable optical attenuator is realized using acoustooptic mode coupling on a cladding etched single-mode fiber. Broad-band coupling bandwidth with low attenuation ripples is achieved by matching both the group index and dispersion parameter between the core and the LP/sub 11//sup cl/ cladding modes. A single-section device exhibits a 10-dB dynamic range with attenuation ripples of <0.5 dB over a spectral range of >100 nm, a response time of 20 /spl mu/s, an insertion loss of 0.3 dB, and a maximum power consumption of only 3.4 mW. Attenuation of 22 dB is obtained for a cascaded two-section device.

Electrically controllable all-fiber PMD emulator using a compact array of thin-film microheaters

An electrically controllable, all-fiber polarization-mode dispersion (PMD) emulator is constructed using thin-film microheaters to temperature tune the birefringence of 30 PM-fiber sections spliced at 45/spl deg/ angles. Compact packaging is achieved by mounting the fiber heaters onto an array of silicon V-grooves. The advantages of this electrically tunable emulator design are low loss, negligible PDL, simple construction, no internal reflections, and no moving parts.

Strain-induced thermally tuned long-period fiber gratings fabricated on a periodically corrugated substrate

This paper reports the characteristics of a strain-induced thermally controlled loss-tunable long-period fiber grating (LPFG) fabricated on a prepatterned corrugated substrate. Periodic microbending at the fiber-substrate interface induces mode coupling between the core and asymmetrical cladding modes that yields narrow-band attenuation as large as -25 dB. Several parameters that affect the performance of the tunable LPFG, such as the diameter of the etched fiber, number of grating periods, curing condition, and thermal expansion properties of the bonding materials, are investigated. This paper also demonstrates the integration of an on-chip thin-film microheater that also functions as a temperature sensor for the LPFG.

Compact, all-fiber PMD emulator using an integrated series of thin-film micro-heaters

We demonstrate a 30-section, compact, all-fiber polarisation mode dispersion (PMD) emulator that uses an integrated series of evaporated micro-heaters to thermally tune the birefringence of each differential group delay (DGD) section and accurately reproduce PMD statistics.

Dynamically reconfigurable all-optical correlators to support ultra-fast internet routing

To implement an effective optical bypass for an electronic router, the key design decision is to combine a software algorithm with a small set of dynamically configurable fiber-Bragg-grating based optical correlators. A conceptual diagram showing how the optical bypass is implemented in an IP router is shown.

Performance characteristics of a WDM channel monitor based on an all-fiber AOTF with an on-fiber photodetector

We demonstrated an all-fiber wavelength-division-multiplexing channel monitor based on a narrow-band acoustooptic tunable filter (AOTF) with a built-in on-fiber photodetector. By employing a frequency-shift keying (FSK) modulation scheme, intrinsic wavelength accuracy of 0.02 nm is obtained for single-channel detection and 0.05 nm for multiple-channel detection. The minimum resolvable channel spacing is 1.0 nm. The measured channel power accuracy is <1 dB. The demonstrated channel monitor showed a polarization-dependent wavelength shift of /spl sim/0.15 nm, which is limited by the polarization mode splitting of the AOTF itself. The influence of FSK frequency spacing and the effect of channel crosstalk are also discussed.

Effects of acoustic reflection on the performance of a cladding-etched all-fiber acoustooptic variable optical attenuator

We analyzed the effects of acoustic reflection on the performance of an acoustooptic variable optical attenuator on a cladding-etched single-mode fiber. It is shown that the acoustic reflection will generate time-dependent modulation on the output optical signal and reduce the maximum achievable attenuation of the device. By employing a tapered fiber structure and using vacuum grease as the acoustic absorber, we showed that the acoustic reflectance can be reduced by two orders and the maximum attenuation of the device is increased from -10 to -29 dB.

Fiber-optic-based optical trapping and detection for lab-on-a-chip (LOC) applications

A three-fiber optical trapping/detection system has been molded in poly(dimethyl siloxane) (PDMS) using anisotropically etched Si V-grooves as the primary or master mold. The process of reverse molding in PDMS maintains the benefits of fiber optic self-alignment previously used in Si V-grooves. Two, pigtailed laser diodes emitting at 830 nm and 980 nm are connected to cleaved, single-mode (SM), counter-propagating fibers, used for trapping polystyrene beads. Orthogonal to the trapping fibers is a multi mode detection fiber coupled to a spectrometer. Chemically treated beads trapped by the 830 and 980 nm diode lasers were excited using a 660 nm diode laser. By utilizing the optical clarity of PDMS, the fourth excitation source fiber is mounted below the PDMS trap and used to excite the trapped beads. Changes in the relative intensity of the trapping light are used to indicate the capture and position of a bead in the trap. Additionally, detection of the excitation source and bead fluorescence is monitored.

An all-fiber WDM channel monitor based on acousto-optic tunable filter with built-in on-fiber detector

An all-fiber WDM channel monitor based on narrowband AOTF and on-fiber detector is demonstrated. By employing FSK modulation scheme, intrinsic wavelength accuracy of 0.02 nm is obtained for single channel detection and 0.05 nm for multiple channel detection.

A loss tunable long-period fiber gratings on corrugated silicon with on-chip microheater and temperature sensor

In summary, we report a strain induced long period grating (LPG) created by bonding an etched single mode fibre (SMF) onto a corrugated Si fixture with on-chip heater and temperature sensor. The loss of the LPG can be tuned electrically through the microheater current and monitored simultaneously. The use of Si fixture lends itself to easy integration of microheater and other cascaded filter structure. The results may be useful for dynamic spectral shaping in DWDM networks.