Base
| Full Name | Karan Ahuja |
| Organization | Gautum Buddha University Delhi |
| Job Title | student |
| Country |
Forum Replies Created
Hi.
One of the optical ports for the Fabry Perot laser is an input port for injection mode locking. So you could use an electrical bias to power the FP Laser then an input from the circulator to drive it. Finally routing the output back through the circulator. You may refer to these links for further help.
https://www.google.co.in/urlsa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwjmgtrAutnNAhWDkZQKHcuzAK4QFgguMAE&url=http%3A%2F%2Foptiwave.com%2F%3Fwpdmdl%3D104&usg=AFQjCNHsqmAw78UVgKXWQv4vUN0iB0nQEg&bvm=bv.126130881,d.dGo
Thanks
Further i want to add that because of its high isolation and low insertion loss, optical circulators are widely used in advanced communication systems as add-drop multiplexers, bi-directional pumps, and chromatic dispersion compensation devices.The example to the left depicts the use of a circulator to drop an optical channel from a DWDM system using a Fiber Bragg Grating (FBG). The input DWDM channels are coupled into Port 1 of the device with a FBG device connected to Port 2. The single wavelength reflected from the FBG then reenters the circulator in port 2 and is routed accordingly to Port 3. The remaining signals pass through the FBG and exit on the top fiber.Circulators can also be used to send optical signal in two directions down a single fiber. A circulator is located at both ends of the fiber. Each circulator functions to add a signal in one direction while removing the signal in the other. See the example to the right.
Here are few more links which can prove very useful to you.
https://www.oplink.com/pdf/PMOC-S0067.pdf
http://www.lasercomponents.com/de/?embedded=1&file=fileadmin/user_upload/home/Datasheets/opto-link/cir-pm.pdf&no_cache=1
https://www.agiltron.com/pdfs/1500%20pm%20circulator.pdf
Thanks
Hi.
Polarization-Maintaining (PM) Optic Circulators are non-reciprocating, unidirectional, three-port devices that are used in a wide range of optical setups. Available with a center wavelength of 1064, 1310 (O-Band), or 1550 nm (C-Band), these circulators are designed to work with light that is launched into the slow axis. Choose from versions with no connectors, FC/PC connectors, or FC/APC connectors.An optical circulator is analogous to an electronic circulator and both perform similar functions. An optical circulator is a three-port device that allows light to travel in only one direction. A signal entering Port 1 will exit Port 2 with minimal loss, while a signal entering Port 2 will exit Port 3 with minimal loss. Light entering port 2 experiences a large amount of loss at port 1, and light entering port 3 experiences a large amount of loss at ports 2 and 1. Optical circulators are non-reciprocal devices. This means that any changes in the properties of the light caused by passing through the device are not reversed by traveling in the opposite direction.
You may refer to these links for the design of PM circulator. I hope it helps.
https://www.agiltron.com/pdfs/1500%20pm%20circulator.pdf
http://www.phoenixphotonics.com/website/products/documents/PolarizationMaintainingCirculator_v01401.pdf
http://www.acphotonics.com/products/Product%20files/Short%20Wavelength%20Circulator/980nm%20PM%20Circulator.htm
Thanks
Further i would like to mention that Optical code division multiple accessm(OCDMA) technique, which allows multiplemusers share the same transmission mediamby assigning different optical codes (OCs)mto different users, is an attractive candidatemfor next generation broadband access networks . The basic architecture and the working principle of an OCDMA passive optical network (PON) network. Partricularly，coherent OCDMA technique is receiving much attention for the overall superior performance over incoherent OCDMA and the development of compact and reliable en/decoders (E/D) like spatial light phase modulator (SLPM), superstructured fiber Bragg grating (SSFBG) and multi-port array waveguide grating (AWG)-type E/D . Previously, on-off-key (OOK) is mostly used as modulation format for payload data in OCDMA system, which is refered as OOKOCDMA. In a multi-user asynchronous coherent OOK-OCDMA system, the major noise sources are the coherent signalinterference (SI) beat noise (coherent noise) and the incoherent MAI (incoherent noise), which limit the number of active users in a network. Therefore, it is essential to combat the SI beat and MAI noises in such a network. Time gating and optical thresholding techniques can be used to suppress the MAI enabling data-rate detection.
Here i am providing with various papers you may consult. These will be very helpful.
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=4290311&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F35%2F4290299%2F04290311
http://file.scirp.org/pdf/JEMAA_2013022815384836.pdf
https://optics.synopsys.com/rsoft/application-gallery/optsim-optical-code-division-multiple-access.html
https://www.eng.tau.ac.il/~tur/pdfs/112.pdf
http://home.eps.hw.ac.uk/~xw66/News%20and%20highlights_files/AOE-invited-xw.pdf
The last paper is about different modulation schemes used in OCDMA. It may be very helpful to you.
Thanks
I also want to add that External modulators offer a way to reduce or eliminate chirp because the laser source is held in the narrow linewidth, steady-state mode. External modulator is typically either a LiNbO3 modulator or an electroabsorptive modulator. In this lesson the chirp induced by the LiNbO3 is analyzed based on the voltage of operation.The modulator is operating in the quadrature mode. This means that the bias voltage places the modulator at the midpoint of the optical response curve, and therefore, the intensity is at half of its peak value. The parameters utilized to setup the modulator. The extinction ratio is set to 200dB to avoid any chirp caused by asymmetric Y-branch waveguide. The modulator is set to work in a non-normalized way, which means the electrical input signal will not be normalized.
You may refer to
Thanks
I want to add that the spectral frequency pattern, with spectral chips centered about the grating frequencies, is determined by signature code properly written in the FBGs. The receiver end applies a matched series of FBGs and a balanced detector for computing correlation difference. The user’s bit stream can now be extracted.The diagram below shows the receiver-end for one of the users, where the received signal is split into an upper branch (FBGs are the same as the encoder) and lower branch (FBGs are the complement of the encoder).
You may go through these links for further study. These will surely help
Thanks
Hello.
An electro-optic switch is a device used in integrated fibre optics. The device is based on Mach-Zehnder interferometer made by Titanium diffusion in Lithium Niobate substrate. The switching between the ports is achieved by an electro-optic effect within such structure. Voltage, applied to the electrodes deposited on the integrated Mach-Zehnder interferometer, creates an electric field distribution within the substrate, which consequently changes its refractive index. If properly designed, the induced change in the refractive index leads to different coupling between individual ports.
You may go through
I hope this will help you.
Thanks
Hi.
The system designed in project SAC OCDMA.osd is a spectral-amplitude- coding OCDMA. It has three users, where in this setup two users are transmitting data, while one user is off. The FBGs in the system are working as encoders/decoders for the incoherent optical signal. Here is the link for the same you may find it useful for your case.
The above design illustrates a 3-user spectral-amplitude-coded OCDMA with two users transmitting data and the other user offline. The FBGs in the system are working as encoders/decoders for the incoherent optical signal.In an SAC-OCDMA system based on FBGs, each user has bits of information that are modulating the broadband incoherent optical carrier to fulfill the E/O conversion (OOK modulation format). A series of FBGs are introduced to control the amplitude spectra of the broadband incoherent optical signals.
I hope this will help you.
Thanks
Hi.
Just click on the folder icon beneath the component library with tow dots under. All the components lie inside this default folder icon. You will find transmitter library receiver library amplifier library fiber library and all desired components inside it.
I hope it will help.
Thanks
I also want to add that External modulators offer a way to reduce or eliminate chirp because the laser source is held in the narrow linewidth, steady-state mode. External modulator is typically either a LiNbO3 modulator or an electroabsorptive modulator. In this lesson the chirp induced by the LiNbO3 is analyzed based on the voltage of operation.The modulator is operating in the quadrature mode. This means that the bias voltage places the modulator at the midpoint of the optical response curve, and therefore, the intensity is at half of its peak value. Figure 2 shows the parameters utilized to setup the modulator. The extinction ratio is set to 200dB to avoid any chirp caused by asymmetric Y-branch waveguides . The modulator is set to work in a non-normalized way, which means the electrical input signal will not be normalized.
You may refer to
Thanks
Hello.
An electro-optic switch is a device used in integrated fibre optics. The device is based on Mach-Zehnder interferometer made by Titanium diffusion in Lithium Niobate substrate. The switching between the ports is achieved by an electro-optic effect within such structure. Voltage, applied to the electrodes deposited on the integrated Mach-Zehnder interferometer, creates an electric field distribution within the substrate, which consequently changes its refractive index. If properly designed, the induced change in the refractive index leads to different coupling between individual ports.
You may go through
Thanks
Hi
As far as your query is concerned i would like to share that solid-state lighting is a rapidly developing field. White-light and other visible LEDs are becoming more efficient, have high reliability and can be incorporated into many lighting applications. Recent examples include car head-lights based on white LEDs, and LED illumination as an architectural feature. The prediction that general illumination will use white LEDs in the future has been made, due to the increased energy efficiency that such an approach may have. Such sources can also be modulated at high-speed, offering the possibility of using sources for simultaneous illumination and data communications. Such visible light communications (VLC) was pioneered in Japan, and there is now growing interest worldwide, including within bodies such as the Visible Light Communications Consortium (VLCC) and the Wireless World Research Forum (WWRF).
Here is link of one paper.
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=4699964&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D4699964
In this paper we outline the basic components in these systems, review the state of the art and discuss some of the challenges and possibilities for this new wireless transmission technique. I hope this will help.
Thanks
I want to add that the integrated semiconductor optical amplifier (SOA) with a reflective electro-absorption modulator (REAM) is a promising candidate for the colorless optical network unit in a wavelength-division-multiplexed passive optical network (WDM-PON), due to its low chirp and wide bandwidth. However, 40 Gb/s operation of REAMs (bandwidth <; 20 GHz) still encounters severe intersymbol interference. Furthermore, Rayleigh backscattering (RB) and discrete reflections cause strong beat noise in WDM-PONs with single-fiber loopback configuration. In this paper, we present two novel techniques based on electrical equalization for a 40-Gb/s single-feeder WDM-PON based on SOA-REAM. The first method is to employ partial-response (PR) signaling and a noise predictive maximum likelihood (NPML) equalizer at the upstream receiver. The other one combines correlative level (CL) pre-coding with partial-response maximum likelihood (PRML) equalization. We experimentally demonstrate a 40-Gb/s uplink of 20 km using a 20-GHz SOA-REAM in a WDM-PON by both PR-NPML and CL-PRML. The results also verify the superiority of PR-NPML over the previously reported equalizers. Moreover, compared with PR-NPML, CL-PRML further improves the system performance. Experiments prove that the tolerance to beat noise and the receiver sensitivity are enhanced by 4 dB and 0.8 dB, respectively, at a bit error ratio of 2 × 10-4.
Here is the link of this paper
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6360172&url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumber%3D6360172
Also DWDM PON architectures are of high interest and are on the way to becoming commercially realized, the bandwidth can be substantially scaled up compared to common PON networks concepts. AWG based structures for MUX/DEMUX applications in WDM-PON networks are ideal, adapting perfectly to PON architectures, allowing cyclic character and are leveraging the state of the art PLC processing techniques. The recent progress of AWG design concepts for DWDM PON architectures and their athermal packaging techniques, now suitable for mass production in low cost manufacturing countries, are discussed. The state of the art reliability performance for industrial and in particular DWDM PON applications are demonstrated. AWG based DWDM PON network architectures are elaborated comparing other existing PON network concepts.And as fas as theoretical aspect of the implementation is concerned i agree with karan ahuja that OFDM has the ability to transmit information with high data rates which has made it popular. OFDM has been used in many different applications in the RF domain
such as digital audio broadcasting (DAB), digital video broadcasting (DVB), and Wireless Local Area Networking (WLAN). OFDM was introduced to
optical domain in 2005, and has since been studied and investigated in two main techniques classified according to the detection scheme. The first technique is the direct detection optical OFDM (DDOFDM) and the second technique is the coherent optical OFDM (CO-OFDM). A direct detection optical OFDM aims for simpler transmitter or receiver than CO-OFDM for lower costs. DD-OFDM has an advantage that it is more immune to impulse clipping noise.
You may refer to this paper in this regard
http://ieeexplore.ieee.org/xpl/login.jsptp=&arnumber=4054038&url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumb
Hi Ranjeet.
I would like to mention that the wavelength-division-multiplexed passive optical network (WDM-PON) has been generally regarded as a promising solution to the next-generation access network that will be required to deliver services over 40 Gb/s. However, fiber dispersion often limits the capacity and reach of WDM-PONs. Compared with dispersion compensation fiber, which is bulky and expensive with significant power loss, digital signal processing is a more suitable way to mitigate chromatic dispersion in PONs. Furthermore, expense is a critical concern in the WDM-PON, due to its need for a large number of lasers and a complex wavelength control mechanism. One practical solution is to reuse the downstream (DS) signal as the carrier for the upstream (US) modulation. In this case, the residual DS signal after remodulation can seriously degrade US transmission. In addition, system performance can be deteriorated by the unwanted reflection as uplinks and downlinks share one wavelength. In this paper, we propose using modified duobinary (MD) coding in the DS to improve its dispersion tolerance and reduce the crosstalk between DS and US induced by remodulation and reflection. MD is a correlative level code that can reduce signal bandwidth and achieve DC balance. We demonstrate a 15 km WDM-PON delivering a 40 Gb/s MD-coded signal in the downlink and a 10 Gb/s on-off keying signal in the uplink. Compared with no coding, the maximal allowable extinction ratio of the DS signal (ERd) is improved by 4 dB. Moreover, the reflection tolerance of the uplink and downlink is enhanced by 5 and 4 dB, respectively. In addition, investigations on the use of different equalizers in the DS to further suppress fiber dispersion confirm that the superior performance of nonlinear equalization in MD-coded transmission and that the network reach can be extended to 25 km by a nonlinear decision feedback equalizer.
Hope this will give you an idea.
http://ieeexplore.ieee.org/xpl/login.jsptp=&arnumber=6645106&url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumber%3D6645106
Thanks