Optical Code Division Multiple Access

==O-CDMA Concept==
[image|O-CDMA system based on a spectral phase encoded time spreading (SPECTS) technique which encodes or decodes by individually phase-shifting slices of optical spectrum (chips)|{UP}Projects%2fOCDMA%2fOCDMA5.png]

Recent advances in wavelength division multiplexing (WDM) and time division multiplexing (TDM) technologies have fueled rapid deployments of optical networks in metro and wide area networks.  Local area networks (LAN), on the other hand, have requirements that are not easily met by WDM or TDM technologies.  Additional hardware and protocols imposed by the WDM and TDM at the distributing nodes unfavorably add the cost and complexity of the LAN.  Code division multiple access (CDMA) networks that utilize spread spectrum techniques have become very popular, especially in cellular radio networks.  Optical-CDMA (O-CDMA) allows very flexible access of the large communication bandwidth available in optical fiber networks with a capability to conceal the data content.  This is possible without relying on complex distributing nodes but with simple reconfiguration of codes at end user nodes.  Many implementations of O-CDMA, using a variety of coding and detection schemes, have been investigated in the last fifteen years.{BR}
[image|Fig. IV.2.  32 user, 10 Gb/s/user O-CDMA network testbed setup.|{UP}Projects%2fOCDMA%2fO-CDMATestBed.gif]
[image|Fig. IV.3.  320 Gb/s (32 user 10 Gb/s) O-CDMA network testbed.|{UP}Projects%2fOCDMA%2fO-CDMAResults.gif]

Fig IV.1.  shows the background architecture of the O-CDMA system based on a spectral phase encoded time spreading (SPECTS) technique which encodes or decodes by individually phase-shifting slices of optical spectrum (chips) constituting a successful error-free 32 user 10 Gb/s/user O-CDMA testbed.{BR}

The above bulk optical-CDMA systems are being integrated onto a single [InP Photonics|InP chip using arrayed waveguide grating],  phase modulators and [MLL|InP based femtosecond lasers] and nonlinear threshold detecting wavelength converters.  Fig III.4. shows the schematic, and Fig. 14 shows the integrated chip. 
[image|Fig. IV.4.  Principles behind InP integration of O-CDMA transmitters and receivers on an InP chip utilizing arrayed waveguide grating, phase modulators and InP based femtosecond lasers and nonlinear threshold detecting wavelength converters.|{UP}Projects%2fOCDMA%2fO-CDMA2.gif]
==O-CDMA People==
{|
| [imageauto|Chunxin Yang|{UP}photos%2fPeople%2fChunxin.jpg]
| [imageauto|Ryan Scott|{UP}photos/People/RyanScott.jpg]
|}
{clear}