Multi-wavelength Filters Research Articles

Electro- and thermo-optic effects on multi-wavelength Solc filters based on χ ^(2) nonlinear quasi-periodic photonic crystals: Erratum

Electro- and thermo-optic effects on multi-wavelength Solc filters based on χ ^(2) nonlinear quasi-periodic photonic crystals: Erratum

Intensity spectra after first-order dispersion of composite models of scalar cyclostationary light

The spectrum of the intensity of dispersed waves obeying cyclostationary statistics is studied. The formalism is based on an exact formula by Marshall and Yariv [IEEE Photon. Technol. Lett.12, 302 (2000)] relating the intensity spectrum after first-order dispersion to the Fourier transform of a certain restriction of the time-averaged fourth-order correlation of the optical wave e(t) before dispersion. The formalism permits a simple computation of the spectrum of composite models defined by the independent addition or multiplication of a stationary and a cyclostationary field. The computations are simplified by introducing the auxiliary field z(tau)(t)=e(t)*e(t+tau), whose power spectral density represents the basic building block for solving the spectrum of composite models. The results are illustrated by a number of examples, including the intensity spectrum after dispersion of analog-modulated, partially coherent carriers, or the complete spectrum of intensity fluctuations of multiwavelength dispersion-based microwave photonic filters.

Multiwavelength narrowband high-reflection filters with low-reflection sidebands

We propose a novel method for the construction of multiwavelength narrowband high-reflection filters consisting of a reflection mirror, a middle structure, and an induced-reflection match stack (IRMS). The results show that the peak position of the proposed reflection filters is identical to that of the transmission filters consisting of the same middle structure and two flanking high-reflection dielectric film stacks. The range in which multiple reflection peaks occur is determined by the degree of overlapping of the forbidden band in the reflection mirror and the conducting band in the middle structure. This range can be extended by changing the dielectric coefficients of the dielectric film stack or by substituting the dielectric reflection mirror with a silver mirror.

Electro- and thermo-optic effects on multi-wavelength Šolc filters based on χ^(2) nonlinear quasi-periodic photonic crystals

We investigate electro- and thermo-optic effects on multi-wavelength Solc filters based on chi(2) nonlinear quasi-periodic photonic crystals. The multi-wavelength Solc filters are composed of two building blocks A and B, in which each containing a pair of antiparallel poled domains, arranged as a Fibonacci sequence. The transmittances at filtering wavelengths can be modulated from 0 to 100% by applying an external voltage but the filtering wave-lengths are unchanged. The filtering wavelengths can be tuned by varying temperature. As temperature decreases, the filtering wavelengths increase (approximately -0.45 nm/degrees C).

Step-changed period chirped long-period fiber gratings fabricated by CO 2 laser

A CO 2 laser and point-by-point method are used for fabricating step-changed period chirped long-period fiber gratings (LPFG). Several types of period chirped LPFGs have been demonstrated, such as, linearly chirp, peak-shape chirp, and cascaded linearly chirp. Unlike uniform LPFGs, the spectrum change such as multiple attenuation peaks, broader spectrum can be seen in these chirp gratings, and the spectral shape can be controlled by the grating period. Especially, the cascaded linearly chirped LPFGs performs a multi-peak as interference between the core mode and cladding mode, which can be used as multi-wavelength filters in fiber optic communication and fiber optic sensors. Also, a linear tuning range of 1.6 nm with –0.559 pm/με tuning rate is achieved in these types of devices by applying an axial strain.

Control of resonance separation over a wide spectral range in multiwavelength resonant grating filters

The spectral separation of resonances within multiwavelength resonant grating filters is studied through the use of a grating layer with constant structural parameters in combination with single-layer, multimode waveguides and multilayer, multimode waveguides. The use of multilayer, multimode waveguides are shown to provide the ability to control resonance separations for multiwavelength filters from hundreds of nanometers to only a few nanometers.

Electro-optic narrowband multi-wavelength filter in aperiodically poled lithium niobate

We report on an iterative design scheme for and the first experimental demonstration of active narrowband multi-wavelength filters based on aperiodically poled lithium niobate crystals. A simultaneous transmission of 8 wavelengths, each with a ~0.45-nm linewidth and nearly 100% peak transmittance, was achieved in such a device. The transmission spectrum of this device can be tuned by temperature at a rate of ~0.65 nm/ degrees C.

Triple-wavelength switchable Erbium doped fiber laser with cascaded asymmetric exposure long-period fiber gratings

The cascaded asymmetric exposure long-period fiber gratings are fabricated by CO(2) laser, which provide multi-wavelength filters with anisotropic transmission spectrum under different states of polarization. Inserting this device in the ring cavity of an erbium-doped fiber laser, a triple-wavelength switchable lasing laser with equal spacing of 2.6 nm has been obtained. Owing to the polarization dependent loss of the new cascaded long-period fiber grating, the wavelength switching of random combination of C(1) (3), C (2) (3), and C(3) (3) is demonstrated through the polarization controlling. We derive the wavelength switch to the polarization characteristic of cascaded asymmetric exposure long-period fiber gratings.

Polarization-insensitive multi-wavelength switching based on polarization-selective long-period fiber gratings

Novel multi-wavelength switching filters based on cascaded long-period fiber gratings and polarization-maintaining fiber in a Sagnac loop configuration are proposed and experimentally demonstrated. The rapid wavelength switching is achieved by an electro-optic polarization controller. The device is independent of the polarization state of the input light due to the bi-directional polarization compensation of the Sagnac loop interferometer although the polarization state of the optical wave filter is rapidly switched by the electro-optic modulator in the loop. The proposed device can be useful for applications to all-channel gating and odd/even-channel switching devices with fine channel selectivity and high-speed response.

Superimposed fiber Bragg grating simulation by the method of single expression for optical CDMA systems

Superimposed fiber Bragg gratings are very attractive as multiwavelength filters for many applications. Particularly, their spectral parameters can be specially tailored to have different passband and linewidth characteristics as a coding-decoding element for optical code-division multiple-access systems. In this letter, we perform a simulation of such structures by implementation of an advanced method of single expression, which accurately describes the wave propagation problem in the stratified media by numerical solution of the wave equation.

Resonance transmission modes in dual-periodical dielectric multilayer films

The resonance transmission modes with high-quality factors may generate in a one-dimensional dual-periodic photonic band-gap structure. The frequency, frequency interval, and number of these modes can be tuned as desired by adjusting its structural parameters. In this letter, we report the experimental and theoretical results on dual-periodical TiO2/SiO2 multilayer films. With perfect transmission and mode controllability, this structure opens a promising way to fabricate multiwavelength filters for future dense wavelength division application.

Polarization-independent integrated optical, acoustically tunable double-stage wavelength filter in LiNbO/sub 3/

We report a polarization-independent integrated acousto-optical double-stage wavelength filter in X-cut, Y-propagating LiNbO/sub 3/. The device consists of a combination of four acousto-optical mode converters, a TE- and a TM-pass polarizer, and two polarization splitters; their specific design and properties are discussed. The filter has a bandwidth of 1.4 nm and a tuning range of 76 nm around /spl lambda/1.55 /spl mu/m. Maximum filter transmission is achieved with a RF drive power of only 80 mW; it excites via a single unidirectional transducer a guided surface acoustic wave driving the four polarization converters of both stages. Fiber-to-fiber insertion loss is 4.6 dB for TM- and 4.8 dB for TE-polarized waves. Multiwavelength filtering has been demonstrated. >

Time and wavelength division multiaccess with acoustooptic tunable filters

Abstract In this article we propose a novel time and wavelength division multiple access (T/WDMA) scheme for a metropolitan area network based on a passive optical star. This scheme supports circuit-switched traffic in an environment with a large number of users with applications that span a broad range of data rates (from voice to full motion video). The scheme can be implemented using acoustooptic tunable filters characterized by a relatively large tuning range (around 100 wavelengths) and a relatively low tuning speed (around 10 μs). Performance of this scheme is studied by simulation for the uniform, single-rate, point-to-point traffic case. We also show how the multiwavelength filtering capability of acoustooptic tunable filters can be used to improve the performance of the proposed T/WDMA scheme.

Experimental demonstration of multiwavelength optical network with microwave subcarriers

The authors use the unique multiwavelength filtering capability of the acousto-optic tunable filter to demonstrate multiple broadband services with only one fixed-wavelength transmitter and receiver per user in the first experimental demonstration of a multiwavelength subcarrier network.