Wavelength Tunable Optical Filter Research Articles

Inquisitive Optical and Electro-Optical Attributes of Azo-Dye Dispersed Nematic Liquid Crystal for Applications in Wavelength-Tunable Optical Filters

Inquisitive Optical and Electro-Optical Attributes of Azo-Dye Dispersed Nematic Liquid Crystal for Applications in Wavelength-Tunable Optical Filters

Bandwidth and wavelength tunable optical passband filter based on silicon multiple microring resonators.

An ultra-compact silicon bandpass filter with wide bandwidth tunability is proposed and experimentally demonstrated. The filter architecture is based on a multiple micro-ring resonator-cascaded structure. A wide bandwidth tunability (from 75 to 300 GHz) can be achieved by controlling the resonant frequency of the microring resonators when a good shape factor (0.24-0.44) is held. The filter has a wide free spectral range (about 1.2 THz). The center wavelength can be tuned over several nanometers linearly. The footprint is only 0.053 mm2.

GHz-bandwidth optical filters based on high-order silicon ring resonators

Previously demonstrated high-order silicon ring filters typically have bandwidths larger than 100 GHz. Here we demonstrate 1-2 GHz-bandwidth filters with very high extinction ratios (~50 dB). The silicon waveguides employed to construct these filters have propagation losses of ~0.5 dB/cm. Each ring of a filter is thermally controlled by metal heaters situated on the top of the ring. With a power dissipation of ~72 mW, the ring resonance can be tuned by one free spectral range, resulting in wavelength-tunable optical filters. Both second-order and fifth-order ring resonators are presented, which can find ready application in microwave/radio frequency signal processing.

Use Piezoelectric Bimorph for the Fiber Bragg Grating Tuner

A wavelength tunable optical filter based on a fiber Bragg grating using piezoelectric bimorph is realized in this paper, and the tuning condition is theoretically and experimentally analyzed. The Bragg central wavelength of the filter can be easily tuned adopting to a DC voltage. The maximum strain of the central wavelength depends upon the maximum operating voltage, and the tuning range efficiency was as high as 1.2pm/V, the reflectivity, shape and the reflective spectrums of the fiber Bragg grating central wavelength almost keep unchanged before and after tunning. This paper provides a reference for optical fiber Bragg grating tuner.with high efficiency.

High-Speed Wavelength-Tunable Optical Filter Using Cascaded Mach–Zehnder Interferometers With Apodized Sampled Gratings

A high-speed wavelength-tunable optical filter is a key device for selecting different wavelength optical packets on a packet-by-packet basis in a photonic packet switching system. In this paper, we describe a high-speed tunable filter using apodized sampled gratings which can achieve the required filter characteristics at low cost. A sampled grating structure that exhibits a comb-like filter response is adopted to obtain a wide tuning range, implemented in InGaAsP-InP deep-ridge waveguides with vertical-groove surface gratings. In addition, apodization is applied to the sampled grating to achieve a high extinction ratio. We fabricate the filter by integrating the sampled gratings within Mach-Zehnder interferometers. The filter exhibits a tuning range of 16 nm, an extinction ratio of 20 dB, a 3-dB transmission bandwidth of 32 GHz, and a switching time of less than 8 ns.

Optical modulation in photonic band gap structures by surface acoustic waves

We investigate theoretically the modulation of light beams in photonic band gap (PBG) structures by surface acoustic waves (SAWs). In these structures, the propagation of light beams can be actively controlled through an external acoustic stimulus. We have extended the mathematically rigorous transfer matrix method to calculate the light flow in PBG structures subjected to the spatial- and time-dependent dielectric function modulation induced by the SAW. The calculational procedure, which applies for SAWs with a frequency much smaller than that of the light, is employed to determine the transmission spectra of a one-dimensional Bragg stack with a cavity and that of a two-dimensional GaAs PBG structure with periodic air holes. We demonstrate that these two structures can be configured as an on∕off optical switch with very high contrast ratios and, in the two-dimensional case as an efficient wavelength-tunable optical filter.

Analysis of a distributed coupling coefficient phase-controlled distributed feedback optical filter

We have proposed a new phase-controlled distributed feedback wavelength tunable optical filter with distributed coupling coefficient. The analysis, which is based on the transfer matrix method, reveals that an almost constant peak transmissivity (gain) of more than 37dB, tuning range of better than 21.7A and side-mode suppression ratio (SMSR) of more than 17dB can be achieved using this structure.

Highly efficient tunable fiber Bragg grating filters using multilayer piezoelectric transducers

We realized a wavelength tunable optical filter based on a fiber Bragg grating using multilayer piezoelectric transducers (MLP). The Bragg wavelength of the filter can be easily tuned in proportion to an applied low DC voltage. The tuning range efficiency was as high as 0.2 nm/V. We realized a 10 nm Bragg wavelength shift by applying as low as 50 V to the MLP. The MLP was also used in a higher order dispersion equalizer which consists of a pair of nonlinearly chirped gratings. A zero dispersion wavelength shift of 7 nm was successfully realized for the equalizer.

Analysis of a multisection and phase-shift-controlled DFB wavelength-tunable optical filter

We have proposed a new multisection and phase-shift-controlled distributed-feedback wavelength-tunable optical filter structure. The analysis, which is based on the transfer matrix method, reveals that this filter can achieve a tuning range of 32 and 42 Å for grating coupling coefficients of 6 and 10 mm−1, respectively with an almost constant peak transmissivity (gain) of more than 30 dB. The side-mode suppression ratio (SMSR) ranges from 12 to 30.21 dB. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 171–175, 2000.

Polarization-independent low-crosstalk polymeric AWG-based tunable filter operating around 1.55 μm

A wavelength tunable optical filter is a beneficial optical component for dense wavelength-division-multiplexed systems. We report a high-performance polymeric arrayed-waveguide grating (AWG)-based tunable filter made of cross-linked silicone and operating around 1.55 /spl mu/m. This filter exhibited a TE-TM polarization shift of <0.03, a crosstalk of <-35 dB, an insertion loss of <3 dB, and an 8.8-nm tuning range in the 25/spl deg/C-75/spl deg/C temperature region.

Wavelength-tunable optical filters with phase-shifted DFB structures

Wavelength-tunable optical filters with phase-shifted DFB structures

Wavelength‐tunable optical filters with phase‐shifted DFB structures

A new wavelength-tunable optical filter which is based on a phase-shift-controlled distributed feedback structure with two phase shifts along its active layer has been studied, in particular, the effects of phase shifts on tuning range, peak power transmissivity, and side-mode suppression ratio (SMSR). The analysis indicates that when ϕ1=ϕ4=π/2, the filter wavelength tuning range is 22.1 Å for the grating coupling coefficient κ=6/ mm while maintaining almost constant transmissivity (gain) of more than 35 dB. The filter SMSR ranges from 11.1 to 25.4 dB. The results for asymmetric values of ϕ1 and ϕ4 are also given. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 119–122, 1997.

Widely tunable 1.5 µm micromechanical opticalfilter usingAlO x /AlGaAs DBR

The authors demonstrate, for the first time, a wavelength tunable optical filter at 1.55 /spl mu/m using micromechanical tuning of a Fabry-Perot resonator with an AlO/sub x//AlGaAs distributed Bragg reflectors (DBR). The use of thermally oxidised AlAs layers, resulting an ultrawide bandwidth, dramatically increased the tuning range and efficiency of the resonator. Very efficient continuous tuning of >50 nm with only a 0.95 V tuning voltage was achieved. The tuning range, limited by our test laser, is expected to be expandable to hundreds of nm.

Analysis of a λ/4-phase-shifted double phase-shift-controlled distributed feedback wavelength tunable optical filter

We have proposed a new /spl lambda//4-phase-shifted double phase-shift-controlled distributed feedback wavelength tunable optical filter structure. Theoretical analysis based on the transfer matrix method reveals that this filter can achieved a wavelength tuning range of 28.3 and 34.3 /spl Aring/ for the grating coupling coefficients of 6 and 10 mm, respectively. The filter has almost constant peak transmissivity (gain) of more than 30 dB within its tuning range, and its side-mode suppression ratio (SMSR) ranges from 15 to 34.7 dB.

An adaptive wavelength tunable optical filter employing an angle-tuned interference filter and an intelligent digital controller

This paper describes an adaptive wavelength tunable optical filter, which is composed of an angle-tuned interference optical filter and an intelligent digital controller. The new angle-tuned interference filter consists of a dielectric interference optical filter and a piezoelectric angle-tuning mechanism. It achieves quick wavelength switching within 2.5 ms in a 30 nm tuning range and a sufficiently low crosstalk less than -30 dB. The intelligent digital controller has two functions: wavelength tracking and wavelength channel selection. Combining these technologies, we have developed a practical low-cost tunable filter suitable for a post-optical-amplifier filter in a high-sensitivity detection system and a channel selector in a WDM system that requires 10-100 ms channel selection time. With a wavelength tracking operation, we have confirmed -35 dBm high-sensitivity detection in 20 nm wavelength range in a 10 Gb/s system. We have also confirmed a wavelength channel selection operation within 18 ms in a three-channel wavelength division multiplexed (WDM) system whose channel spacing is 4.4 nm.

Surface micromachined Fabry-Perot tunable filter

We report the fabrication of a wavelength tunable optical filter using surface micromachining technology. The center wavelength is 1.517 /spl mu/m and the transmission bandwidth is 5 nm. The device with a 50-/spl mu/m diameter aperture has an optical loss of about 5 dB. A continuous wavelength tuning of 60 nm has been demonstrated. This device may find applications in optical sensing and wavelength division multiplexing systems, and can be readily integrated with surface emitting lasers, modulators, and detectors.

Theoretical analysis of multiple‐phase‐shift‐controlled distributed feedback wavelength tunable optical filters

AbstractA three‐phase‐shift‐controlled wavelength tunable optical filter is proposed. Theoretical calculation based on the transfer matrix method indicates a tuning range of more than 30 Å. The peak gain and bandwidth are almost constant during tuning. The side‐mode suppression is over 25 dB.

SEMICONDUCTOR WAVELENGTH TUNABLE OPTICAL FILTERS

Wavelength-division multiplexing (WDM) lightwave transmission systems and wavelength-division (WD) photonic switching systems are attractive for improvement in line capacity for lightwave telecommunication services, because they utilize a huge wavelength (frequency) domain as signal channels. Wavelength tunable optical filters are key devices for these WDM and WD systems in direct detection scheme. In particular, semiconductor wavelength tunable optical filters are suitable for monolithic integration with photonic devices such as semiconductor lasers, switches and detectors. Also, the switching speed of wavelength is faster than that of other optical filters. This paper briefly summarizes the state-of-the-art semiconductor wavelength tunable optical filters and their applications to WD photonic switching systems.

Tapered, resonant DBR transmission filters

Wavelength-tunable optical filters, in the form of resonant distributed Bragg reflector laser filters, have been fabricated and evaluated. The devices are specially designed as transmission filters and have a novel structure, using low coupling strength in the grating and an up-tapered active section, in order to improve the crosstalk performance and the saturation properties. Fabricated devices have 6-8-dB dynamic range and would give less than 1-dB crosstalk penalty in four-channel systems at 13-dB chip gain. System experiments with two 2-Gb/s channels are reported. >

1.5 mu m phase-shift-controlled distributed feedback wavelength tunable optical filter

A 1.5- mu m phase-shift-controlled distributed feedback wavelength tunable optical filter is studied. This wavelength tunable optical filter controls the transmissivity (gain) and the transmission wavelength independently by current injection. During wavelength tuning, the submode suppression ratio is large and a wavelength tuning range as wide as 120 GHz (9.5 AA) with 24.5-dB constant gain is achieved. An 18-channel wavelength selection with less than -10 dB crosstalk is expected with this filter. The effect of the light input, whose wavelength is in the sidelobe, on the transmission spectrum shape is shown.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>