Tunable Fiber Bragg Grating Research Articles

Bi-directional ROADM with one pair of N x N cyclic-AWGs for over N wavelength channels configuration

Abstract This paper presents a bidirectional optical add-drop multiplexer (BROADM) with permitting white spectral channels input in bidirectional configuration. The filter routing rule of array waveguide grating (AWG) is applied for the wavelength channels (WCs) that need to be added and dropped by using the corresponding tunable fiber Bragg gratings (FBGs). The other WCs pass through output by tuning FBG filter spectra away from the WCs. The bandwidth between two adjacent WCs of each pair of ports in AWG is wider than one channel spacing so that the filter spectra of FBG is tuned to free spectral range (FSR) region to realize the wavelength routing function without interfering other WCs. The WCs can be flexibly handled by installing the corresponding tunable FBG. Therefore, the proposed BROADM is more flexible and has higher transmission capacity in the optical network.

A Temperature-Independent Interrogation Technique for FBG Sensors Using Monolithic Multilayer Piezoelectric Actuators

In this paper, a temperature-independent technique for measurements of ac signals, such as voltage and electrical current, with fiber Bragg grating (FBG) sensors is presented. This technique is based on a twin-grating scheme, in which the measured quantity is obtained from the optical power of convolution between a sensing FBG and a tunable FBG. The proposed interrogator employs a low-voltage monolithic multilayer piezoelectric actuator (MMPA) to sweep the tunable FBG over the wavelength range of the sensing FBG, in order to obtain the convolution function accurately. A dedicated microcontrolled optoelectronic system with a firmware-based tracking routine is responsible for keeping the tunable FBG following the sensing FBG over temperature-induced wavelength shifts with subpicometric resolution, while the dc level of convolution is controlled precisely at the highest sensitivity point of operation. The MMPA employed allows the tracking of the tunable FBG after the sensing FBG over a maximum temperature difference that ranges from −29 °C to +90 °C. The proposed interrogator presents lower cost compared with the systems that employ frequency-scanning devices, such as high-speed Fabry-Perot tunable filters.

A Power Compensated Novel Architecture of RM-OXC Based on T-FBG and OC: A High-speed and Cost-effective System

Abstract This paper presents a high-speed, power-compensated novel architecture of N×N reconfigurable multiwavelength optical cross connect (RM-OXC) based on tunable fiber Bragg grating (T-FBG) and optical circulator (OC). FBG and OC-based OXCs are network elements that play a significant role in optical networks to offer more network survivability and reconfiguration flexibility. Optical signal-to-noise ratio of 71.05, 69.05 and 67.05 dB is achieved with acceptable quality factor of 7.54, 6.95 and 6.41, respectively, with 10 Gbps having input transmission power of −8 dBm at different transmission distances (40, 50, 60 km). It is found that the signal is communicated to a maximum distance of 60 km in the presence of fiber nonlinearities without optical amplifier at 0.8-nm channel spacing.

Optimization and efficient routing scenario of system using C-band: reconfigurable multiwavelength optical cross connect based on tunable fiber Bragg grating and optical circulator

Optimization and efficient routing scenario of system using C-band: reconfigurable multiwavelength optical cross connect based on tunable fiber Bragg grating and optical circulator

A widely tunable fiber ring laser with closed loop control based on high-precision stepper motor

A tunable single-longitudinal mode erbium-doped fiber ring laser based on stepper motor and closed loop control is proposed and demonstrated. The system consists of an erbium-doped fiber (EDF), a tunable fiber Bragg grating (FBG) filter and a wavelength detector. The characteristics of output laser, such as output power, power stability and 3-dB linewidth, are investigated in the operation range of 1 531—1 569 nm. The repeated experimental results of the fiber laser show that the 3-dB linewidth is less than 17 ps, the side-mode suppression ratio (SMSR) is up to 60 dB, the output power is up to 1.37 dBm, and the power variation is less than 0.61 dB.

Wavelength tunable TFBG based microwave sensor using surface plasmon resonance

A noble idea is used to propose a wavelength tunable tilted Fiber Bragg Gratings based microwave sensor using surface plasmon resonance. The Bragg wavelength shifts linearly about 6pm/°C, due to the temperature change. This temperature variation occurs because of the microwave–metal interaction at cladding layer of the optical fiber based proposed sensor. The wavelength tuning can be achieved by using tilted Fiber Bragg Gratings. To use the wavelength sources of 850nm, 1310nm and 1550nm, tiled Fiber Bragg Gratings with grating periods of 293.65nm, 452.56nm and 535.47nm respectively are required in the same fiber with certain distances among them.

Stable Dual-Wavelength Coherent Source With Tunable Wavelength Spacing Generated By Spectral Slicing a Mode-Locked Laser Using Microring Resonator

We demonstrate a stable tunable dual-wavelength erbium-doped fiber laser generated by launching a mode-locked laser into an add–drop microring resonator. Two silicon-based high-index-contrast microring resonators with $Q$ -factors of 1.2 × 10 5 and 0.6 × 10 5 have been used as add–drop filters independently. As a result, multiwavelength generation was achieved and demonstrated both theoretically and experimentally with free spectral range (FSR) of 0.202 and 0.404 nm corresponding to the microrings' diameter of $\textrm{D}=2.54$ and $\textrm{D}=1.27\,\mbox{mm}$ . A high-resolution tunable bandpass filter and fiber Bragg gratings (FBGs) are then used to extract a tunable and switchable dual-wavelength coherent source from the generated multiwavelength coherent source. Subsequently, the dual-wavelength coherent source with tunable FSRs from 0.404 to 3.232 nm is achieved and presented. The obtained dual-wavelength output has a side-mode suppression ratio of more than 30 dB.

A multi-band access radio-over-fiber link with SSB optical millimeter-wave signals based on optical carrier suppression modulation

In this paper, we have reported a radio-over-fiber (RoF) link with a single sideband (SSB) optical millimeter (mm)-wave signal to support the 20GHz, 40GHz and 60GHz mm-wave multiband wireless accesses, based on the optical carrier suppression (OCS) modulation via a nested Mach–Zehnder modulator (MZM). The downstream data is only modulated on one of the multiple tones of the optical signal. At the base station (BS), according to the requirement of the wireless users, the multitone optical signal can be decomposed as different SSB optical signals using tunable fiber Bragg gratings (FBGs). Each SSB optical signal consists of two tones: the data-bearing optical tone and a referenced optical local oscillator to convert the baseband optical signal to the electrical mm-wave one based on heterodyne beating. The simulation results reveal that our proposed scheme can provide multiband wireless accesses and without dispersion compensation after 30km single-mode fiber (SMF), the 10Gb/s 4-QAM downstream data on the three-band mm-waves have minor degradation.

A tunable dual-wavelength fiber Bragg grating laser using an external-injected DFB laser

A tunable dual-wavelength fiber Bragg grating (FBG) laser based on a distributed feedback (DFB) laser injection is proposed and experimentally demonstrated. The wavelength spacing can be tuned by adjusting the operation temperature of the DFB laser. When the DFB works at 25 °C, a dual-wavelength simultaneous oscillation at 1 549.67 nm and 1 553.44 nm with wavelength spacing of 3.77 nm is achieved. Our experimental results demonstrate the new concept of dual-wavelength lasing with a DFB laser injection and the technical feasibility.

Dynamic wired-wireless architecture for WDM stacking access networks

This paper presents a dynamic architecture for convergent wired and wireless access networks in Time Division Multiplexing (TDM) based Passive Optical Network (PON) featuring wavelength stacking. Four wavelengths for wired services carrying 10 Gb/s traffic load, one shared extra reconfigurable wavelength and one wavelength common to all Optical Network Units (ONUs) for the transport of wireless services were launched into a 1:64 splitting ratio PON network. In the ONU, a tunable free spaced Fourier optics based filter selects one of the wavelengths conveying wired services and a tunable Fiber Bragg Grating (FBG) filters out the wavelength carrying the wireless services. In the uplink direction, subcarrier multiplexing (SCM) was used for the combined transport of the wired and wireless signals to the Central Office (CO).

Bidirectional Wavelength Reconfigurable Module Based on Tunable Fiber Bragg Grating and Remote Pump Amplifier

This article presents a novel bidirectional wavelength reconfigurable optical network utilizing a remotely pumped erbium-doped fiber amplifier and tunable fiber Bragg gratings. The system is experimentally demonstrated at a 10-Gb/s per channel over 20-km fiber span that verifies the metro-network range system performance. The achieved power penalty is less than 1 dB when compared to the back-to-back transmission link. An example of practical application where the proposed module is used as an add/drop multiplexer and a remote node in the bidirectional wavelength division multiplexing passive optical network system is described.

Single-longitudinal-mode operation in tunable novel zirconia–yttria–alumina–erbium-doped fiber laser

A tunable, single-longitudinal-mode (SLM) fiber laser based on a short length, highly doped zirconia–erbium doped fiber (Zr-EDF) is proposed and demonstrated. The Zr-EDF is a novel fiber with an erbium ion concentration of 4320 ppm wt − 1 and an absorption rate of approximately 22.0 dB m − 1 at 978 nm, while at the same time being highly compatible with conventional silica-based optical fibers. The Zr-EDF is used as the gain medium in the laser cavity, while a tunable C-band fiber Bragg grating is used to adjust the operating wavelength of the system, providing an operating wavelength range of between 1533.8 nm to 1545.0 nm. Two short erbium-doped fibers, with active ion concentrations of 900 ppm wt − 1, serve as saturable absorbers, and allow for an SLM output with a narrow laser linewidth of only 0.2 MHz. The proposed system has multiple applications as a tunable SLM laser for communications and sensing purposes.

Widely tunable chaotic fiber laser for WDM-PON detection

A widely tunable high precision chaotic fiber laser is proposed and experimentally demonstrated. A tunable fiber Bragg grating (TFBG) filter is used as a tuning element to determine the turning range from 1533 nm to 1558 nm with a linewidth of 0.5 nm at any wavelength. The wide tuning range is capable of supporting 32 wavelength-division multiplexing (WDM) channels with 100 GHz channel spacing. All single wavelengths are found to be chaotic with 10 GHz bandwidth. The full width at half maximum (FWHM) of the chaotic correlation curve of the different wavelengths is on a picosecond time scale, thereby offering millimeter spatial resolution in WDM detection.

A Closed-Loop Interrogation Technique for Multi-Point Temperature Measurement Using Fiber Bragg Gratings

In this paper a closed-loop interrogation technique for multi-point temperature measurement using fiber Bragg gratings (FBG) is presented. The technique uses a broadband light source and n tunable FBGs to interrogate an array of n FBGs sensors placed along the optical fiber. Each center wavelength of the tunable FBGs is matched with the center wavelength of one FBG sensor placed in the array. The light source directly illuminates the sensor array, so that all the light reflected from the FBGs enters in the optical circuit through an optical circulator and the reflected spectrum of each sensing FBG illuminates a matched tunable FBG. Because the current generated by the photodiode is proportional to the convolution between the two FBGs profiles (the sensor FBG and the tunable FBG), by controlling the value of the convolution at a fixed value, the center wavelengths of the two FBGs are kept spaced by a constant value. Therefore, the temperature of the FBG sensor can be associated with the temperature of the tunable FBG. A two channel prototype was constructed to validate the technique and a very high resolution of ±0.001 °C was obtained.

Configuration of more than N DWDM channels with only one N × N cyclic-AWG-based wavelength routing device

A wavelength routing device based on only one N×N cyclic arrayed waveguide grating (AWG) having easy extended channels configuration is presented in this paper. It is easy to extend the dense wavelength division multiplexing (DWDM) channel configuration through this wavelength routing device. According to the cyclic wavelength of AWG, the wavelength routing devices are easy to configure more than N extended DWDM channels through cascading more proper tunable fiber Bragg gratings (FBGs). With only one 8×8 AWG, two different wavelength routing structures were built to evaluate static crosstalk and the bit-error-rate (BER). Three of the 16 inputted DWDM channels were demonstrated to verify that the proposed wavelength routing device, with only one 8×8 AWG, could configure extended DWDM channels without interfering with other channels. The results show that the wavelength routing device can produces a better performance and offers a cheaper way to extend the DWDM channel configuration for a dynamic network.

Fault detection technique for wavelength division multiplexing passive optical network using chaotic fiber laser

We propose a fault localization method for wavelength division multiplexing passive optical network (WDM-PON). A proof-of-concept experiment was demonstrated by utilizing the wavelength tunable chaotic laser generated from an erbium-doped fiber ring laser with a manual tunable fiber Bragg grating (TFBG) filter. The range of the chaotic lasing wavelength can cover the C-band. Basing on the TFBG filter, we can adjust the wavelength of the chaotic laser to match the WDM-PON channel with identical wavelength. We determined the fault location by calculating the cross-correlation between the reference and return signals. Analysis of the characteristics of the wavelength tunable chaotic laser showed that the breakpoint, the loose connector, and the mismatch connector could be precisely located. A dynamic range of approximately 23.8dB and a spatial resolution of 4cm, which was independent of the measuring range, were obtained.

A compact graphene Q-switched erbium-doped fiber laser using optical circulator and tunable fiber Bragg grating

We demonstrate a passively Q-switched tunable erbium-doped fiber laser (EDFL) based on graphene as a saturable absorber (SA). A three-port optical circulator (OC) and a strain-induced tunable fiber Bragg grating (TFBG) are used as the two end mirrors in an all-fiber linear cavity. The Q-switched EDFL has a low pump threshold of 23.8 mW. The pulse repetition rate of the fiber laser can be widely changed from 9.3 kHz to 69.7 kHz by increasing the pump power from 23.8 mW to 219.9 mW. The minimum pulse duration is 1.7 μs and the highest pulse energy is 25.4 nJ. The emission wavelength of the laser can be tuned from 1560.43 nm to 1566.27 nm by changing the central wavelength of the strain-induced TFBG.

Widely tunable mode-locked all-fiberized Yb-doped fiber laser with near-transform-limited spectrum linewidth

A widely tunable mode-locked all-fiberized Yb-doped fiber laser with near-transform-limited spectrum linewidth is used. It consists of a tunable fiber Bragg grating (TFBG) and a fiber-coupled LiNbO3 phase modulator (PM) in a linear cavity. The TFBG is used to achieve tunable emission wavelength, and the intracavity PM is used to achieve actively mode-locking operation. We have experimentally demonstrated that the laser-emitting wavelength can be tuned between 1,041 and 1,091 nm with power fluctuation less than 3 dB. The temporal width of the laser pulse is about 1 ns, and the pulses are near transform-limited with a spectral linewidth of 1.3 GHz. The results may find useful application in optical communication and optical measurement system.

Widely Tunable Fiber Bragg Grating and its Application in Fiber Lasers

ABSTRACTThe article describes a simple design to make a widely tunable fiber Bragg grating (FBG) filter with a minimum tuning range of 0.02 nm, and its application to develop a widely tunable, single‐longitudinal‐mode, medium‐power fiber laser. The tunable grating was developed using a commercially available FBG. The maximum tuning range of the laser was 35 nm, which was due to the available gain from the laser gain medium. The laser was operating at room temperature. The laser was free from mode hopping and produced more than 300 mW output power at room temperature. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2824–2826, 2013

A wavelength routing device by using cyclic AWGs and tunable FBGs

This paper presents a dense wavelength-division multiplexing (DWDM) routing device based on a pair of 1×N and N×1 cyclic array waveguide gratings (AWGs) and tunable fiber Bragg gratings (FBGs) to configure all channels in a dynamic network. With the AWG cyclic spectral routing rule, all the DWDM channels (e.g., more than 8 DWDM channels can be configured based on a pair of cyclic 1×8 and 8×1 AWGs) can be added and dropped by using the multiple tunable FBGs to reflect the channels that need to be dropped to the drop port as well as to reflect the local DWDM channels that are same as the drop wavelength channels to the output port. Three DWDM channels are demonstrated to verify that all the DWDM channels can be added and dropped in one pair of cyclic AWGs. The results show that the proposed DWDM routing device is feasible to use and offers more flexibility in all-optics dynamic networks.