A dual-wavelength erbium-doped fiber (EDF) variable ring laser using a fiber acousto-optic tunable filter (AOTF) and
highly nonlinear fiber (HNLF) is demonstrated. Stable and variable lasing wavelengths were achieved by electronically
adjusting the AOTF settings.
A new method to create a long-period fiber grating utilizing a scanning CO2 laser with varying scanning velocities is reported that results in strong grating (>30dB loss) with extremely short grating length (1.1-cm) all achieved with low insertion loss (<2dB).
The principle, experimental implementation and verification, as well as preliminary device demonstrations of coherent acousto-optic mode coupling using a pair of acoustic gratings on dispersion compensating fibers (DCFs) are reviewed. The embodiment of polarization-dependent narrowband mode coupling and wavelength tuning features in a single strand of optical fiber offers interesting opportunities for functional integration in an all-fiber medium, and the generation of fiber optical vortex modes.
We demonstrate a new all-fiber spectrometer based on acousto-optic tunable filter (AOTF) on cladding etched single-mode (SM) fiber. The spectrometer has a free spectral range (FSR) of 200 nm, a wavelength resolution of 2 nm, a dynamic range of 20 dB and a potential scanning rate of ~125 μs/sample. The spectrometer has the potential to be developed as a low-cost spectral monitoring device for dynamic gain equalizer (DGE) in Er-doped fiber amplifier modules.
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.
A four-fiber optical trapping/detection system build on silicon, utilizing the natural alignment of anisotropically etched Si V-grooves for positioning of the optical fibers, has been demonstrated. Two, pigtailed laser diodes emitting at 830 nm are connected to cleaved, single-mode, counter- propagating fibers, which are used for trapping polystyrene beads. Orthogonal to the trapping fibers are two additional fibers: one fiber is connected to a laser diode emitting at 660 nm (excitation source) and the opposing detection fiber is connected to a spectrometer. Changes in the relative intensity of the trapping light and the excitation light are used to indicate the capture and position of a bead in the trap. The spectrometer may be interfaced with a computer allowing for complete automation for position, size and fluorescence detection of the trap with an eventual goal of integration with MEMS (Micro ElectroMechanical Systems) and lab on a chip (LOC) technology.
We describe a novel electrically tunable fiber Bragg grating (FBG) filter with a chemically etched cladding and an evaporated metal coating on one side of the fiber. Wavelength tuning ranges up to 2.5 nm with efficiencies greater than 8.5 nm/watt have been demonstrated along with modulation bandwidths up to 14 Hz. We have also demonstrated tuning efficiencies over 200nm/Watt for 30micrometers diameter etched cladding devices tuned under moderate vacuum conditions. Such tunable FBG filters have potential applications in dense wavelength division multiplexing (DWDM), optical signal processing, or in wavelength tunable fiber lasers. In our paper we investigate the tuning efficiency and modulation bandwidth of etched cladding FBGs integrated with Silicon V-grooves that utilize temperature tuning of the filter. By passing an electrical current through a thin metal coating deposited onto an etched cladding FBG, the temperature of the grating can be controlled to tune the spectral characteristics of the FBG. Additionally, to simplify the fabrication process, we evaporate the metal coating onto the etched FBG from only one side. This radially asymmetric metal coating is simpler to fabricate, since it does not require any mechanical fixture to rotate the fiber during metal deposition. The etched cladding FBG is placed in a Si V-groove that serves the multiple functions of holding the FBG during etching and evaporation, and also provides a simple and compact means for scaling up to arrays of tunable FBGs.