A compact all-fiber PDL-compensated acoustooptic wavelength monitor (original) (raw)
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All-fiber acousto-optic polarization monitor
Optics Letters, 2007
We describe the operational principle of and experimentally demonstrate a narrowband, wavelength-tunable polarization monitor based on a fiber acousto-optic tunable filter. Two orthogonally vibrating acoustic waves are used to create a variable polarizer that can be used to measure the state of polarization of an incident narrowband light source. The accuracy of the polarization monitor is measured at two different wavelengths in reference to a commercial polarimeter and is shown to be within 5%.
A Low Polarization Sensitivity All-Fiber Wavelength Measurement System
IEEE Photonics Technology Letters, 2008
A low polarization-sensitive all-fiber wavelength measurement system using a twisted macro-bend fiber edge filter together with polarization-insensitive (PI) 3-dB coupler is presented. Eliminating the polarization-dependent loss (PDL) is essential when macro-bending single-mode fiber is utilized as an edge filter. A new bending configuration to eliminate the PDL of a fiber edge filter is proposed in this letter by twisting the fiber by 90 between two bending sections with equal length. The PDL of this configuration retains a low value even while the bending length is increased to achieve a steeper response for the edge filter. This configuration together with a PI 3-dB coupler makes the system to have very low polarization sensitivity and as a result high wavelength accuracy can be achieved.
Optics Letters, 2005
We analyze the transmission characteristics of a Sagnac loop interferometer containing a polarizationdependent loss element and lossless polarization-converting elements by use of Jones matrices. We show that polarization independence in the transmission mode can be achieved in such a configuration and that maximum transmittance occurs when a half-wave plate is used for the polarization-converting element. The result is verified experimentally for a fiber acousto-optic tunable filter and cascaded long-period fiber gratings with either intrinsic or process-induced polarization-dependent filtering characteristics.
Principles and analytical applications of acousto-optic tunable filters, an overview
Talanta, 1997
Advantages of acousto-optic tunable filters have been exploited to develop novel analytical instruments which are not feasible otherwise. The instrumentation development and unique features of such AOTF based instruments including the multidimensional fluorimeter, the multiwavelength thermal lens spectrometer, the near-infrared spectrometer based on erbium doped fiber amplifier (EDFA), and detectors for high performance liquid chromatography (HPLC) and flow injection analysis (FIA), will be described. © 1997 Elsevier Science B.V. £ = vs(n~ --no)/2
Narrow bandwidth grating-assisted acousto-optic tunable filter
1998
An experimental acousto-optic tunable filter that has a narrow spectral bandwidth (0.2 nm at 1550 nm) and a fast (10 psec) tuning capability with a continuous tuning range of 52 nm is described. By combining a conventional diffraction grating with an acousto-optic beam deflector, spectral bandwidth has been significantly reduced and the number of usable wavelength channels within the erbium-doped fiber amplifier (EDFA) passband is increased by approximately 20 times. The filter also permits simultaneous and independent selection/routing of many wavelength channels for multi-channel wavelength division multiplexing (WDM) filters/routers/switches or fast scan optical spectrum analyses.
Fiber-Optic Remote Multisensor System Based on an Acousto-Optic Tunable Filter (AOTF)
Applied Spectroscopy, 1996
This paper describes a new fiber-optic multisensor based on an acousto-optic tunable filter (AOTF) and capable of remote sensing using a multioptical fiber array (MOFA). A two-dimensional charge-coupled device (CCD) was used as a detector, and the AOTF was used as a wavelength selector. Unlike a tunable grating or prism-based monochromator, an AOTF has no moving parts, and an AOTF can be rapidly tuned to any wavelength in its operating range within microseconds. The large aperture of the AOTF allows the optical signal from over 100 fiber-optic sensors to be measured simultaneously. These characteristics, combined with their small size, make AOTFs an important new alternative to conventional monochromators, especially for spectral multisensing and imaging. A prototype fiber-optic multisensor system has been developed, and its feasibility for simultaneous detection of molecular luminescence signal via fiber-optic probes is demonstrated.
All-fiber and fiber compatible acousto-optic modulators with potential biomedical applications
Optical Fibers and Sensors for Medical Diagnostics and Treatment Applications VI, 2006
All-fiber acousto-optic (AO) devices such as frequency shifters, phase, intensity and polarization modulators, tunable filters and multiplexers have been developed in the last decade mostly for their importance in fiber optic communication systems. However they can equally have potential uses in bio sensing and fiber based biomedical systems. We present the design, construction and performance of a number of all-fiber and fiber compatible acousto-optic modulators that particularly phase and polarization modulators and will address their potential uses in biomedicine. Among these components and devices, an all-fibre phase modulator acts on the phase of optical fields that propagate down the fibre core. To enhance the phase modulation, the acoustic energy is focused into the fiber core using an acoustic lens. Another high efficiency birefringence (or polarization) modulator was demonstrated that is designed to operate at the acoustic resonance frequency of the fiber. Fiber compatible devices were built using gradient index (GRIN) lenses that can couple the light into a fiber or between two fibers. Diffraction based and polarization GRIN modulators were demonstrated and AOMs of in-fiber gratings as well as ones made from glasses that exhibit large AO figure of merit. As a high frequency polarization, phase, intensity or wavelength modulators these devices have a great potential for use in polarimetric imaging, scanning of a fiber-optic OCT system, tuning the wavelengths in miniature hyperspectral imaging systems and sensors or for frequency-domain OCT.
Deep-Uv Based Acousto-Optic Tunable Filter for Spectral Sensing Applications
International Journal of High Speed Electronics and Systems, 2007
In this paper, recent progress made in the development of quartz and KDP crystal based acousto-optic tunable filters (AOTF) are presented. These AOTFs are developed for operation over deep-UV to near-UV wavelengths of 190 nm to 400 nm. Preliminary output performance measurements of quartz AOTF and design specifications of KDP AOTF are presented. At 355 nm, the quartz AOTF device offered ∼15% diffraction efficiency with a passband full-width-half-maximum (FWHM) of less than 0.0625 nm. Further characterization of quartz AOTF devices at deep-UV wavelengths is progressing. The hermetic packaging of KDP AOTF is nearing completion. The solid-state optical sources being used for excitation include nonlinear optics based high-energy tunable UV transmitters that operate around 320 nm and 308 nm wavelengths, and a tunable deep-UV laser operating over 193 nm to 210 nm. These AOTF devices have been developed as turn-key devices for primarily for space-based chemical and biological sensing appli...
Polarization-Independent Tunable Fiber Comb Filter
IEEE Photonics Technology Letters, 2004
We have demonstrated a polarization-independent tunable fiber comb filter by using both polarization-diversity loop technique and birefringence tuning technique. The proposed apparatus consists of one polarization beam splitter, polarization-maintaining fibers, and three waveplates (one quarter-wave plate and two half-wave plates). The capability of continuously tuning the output spectrum was theoretically analyzed and then experimentally verified.