We propose and experimentally demonstrate a hybrid WDM/OCDMA ring with a dynamic add/drop function based on Fourier code for local area networks. Dynamic function is implemented by mechanically tuning the Fourier encoder/decoder for optical code division multiple access (OCDMA) encoding/decoding. Wavelength division multiplexing (WDM) is utilized for node assignment and 4-chip Fourier code recovers the matched signal from the codes. For an optical source well adapted to WDM channels and its short optical pulse generation, reflective semiconductor optical amplifiers (RSOAs) are used with a fiber Bragg grating (FBG) and gain-switched. To demonstrate we experimentally investigated a two-node hybrid WDM/OCDMA ring with a 4-chip Fourier encoder/decoder fabricated by cascading four FBGs with the bit error rate (BER) of <10(-9) for the node span of 10.64 km at 1.25 Gb/s.

We propose and experimentally demonstrate upstream transmission in a wavelength division multiplexing/optical code division multiplexing (WDM/ OCDM) passive optical network (PON) without using any high-cost devices such as mode-locked lasers or LiNbO 3 external modulators. To make optical network units (ONUs) simple, a loop-back transmission of short optical pulses for OCDM in upstream transmission was investigated. The quality of the short optical pulses, remotely supplied via 23 km of single-mode fiber (SMF), was sufficient for 4-chip OCDM encoding at the ONUs. 2WDM/4OCDM signals, generated by multiplexing four OCDM signals using the same wavelength as well as another signal with a different wavelength, showed error-free transmission (bit error rate BER < 10 −9 ) over a 23 km SMF at 1.25 Gb∕s.Index Terms-Optical code division multiplexing (OCDM); Passive optical network (PON); Reflective semiconductor optical amplifier (RSOA); Short optical pulse source; Wavelength division multiplexing (WDM).

A simple and feasible techniques for ultra-wideband (UWB) triplet pulse generation based on gain switching of self-seeded reflective semiconductor optical amplifier (RSOA) is proposed and demonstrated. The proposed system consisted of RSOA, erbium doped fiber laser (EDFA), two fiber Bragg gratings (FBGs), and balanced photo detector (BPD). The short pulse train which has a low timing jitters and pulse width was generated based on gain switching of RSOA. The generated optical triplet Gaussian pulse was well match the Federal Communications Commission (FCC) mask in frequency domain. Generated UWB triplet pulse has a fractional bandwidth of about 146% and pulse width of 293ps, respectively.

at 3.8 GHz is clearly observed, which gives about À33 dB rejection. At the rejection band of 2.3-12 GHz, the rejection of the transmission is less than about À20 dB. In Figure 5, the simulated result is in well agreement with the measured result. In Figure 6, the measured result of the proposed LPF provides better rejection characteristics than that of the conventional one whose size is 38.3 Â 25 mm 2 . CONCLUSIONSA compact LPF for wideband rejection is discussed and its brief design procedure is also described. DSISS and BDGS may yield slow wave effect, which can be resulted in small circuit size, sharp cutoff, and wide band rejection characteristics compared with the conventional LPF using SISS and CDGS. The size reduction of the proposed LPFs is about 23% compared with the conventional LPF. The proposed LPF is obtained in wideband rejection that is below À20 dB from 2.3 to 12 GHz. Photonic microwave filters (PMFs) have attracted a great deal of research interest recently because of their ability to allow the processing of radio frequency signals in the optical domain while maintaining the advantages of wide bandwidth, immunity to electromagnetic interference (EMI), and low loss [1][2][3]. They can be used in a wide range of radar applications and wireless communications. Generally, PMFs have been implemented based on the concept of a digital filter, in which the output is produced by summing the delayed components of the input signal with an individually assigned coefficient. The filter characteristic therefore depends on the number of optical sources being used and the available coefficients. To implement high quality multi-tap filters, then, several optical sources are required, increasing the system cost. For this reason, spectrum-sliced optical sources using the amplified spontaneous emission noise of an erbiumdoped fiber (EDFA) [4] and a broad band super-luminescent LED (SLED) [5] have been implemented to reduce the filter cost. These methods, however, are limited in their tuning range, notch dip, and modulation frequency.In this respect, we propose and experimentally demonstrate a tunable photonic microwave notch filter using a reflective semiconductor optical amplifier (RSOA) together with fiber Bragg gratings (FBGs) with no additional high cost optical source. The RSOA is self-injection locked by the individual grating and acts as a multi-wavelength source. The available wavelength peaks are determined by the gain bandwidth of the ROSA (C band, 30 nm), the optical power necessary for multiple locking, the pass band of the FBGs, and the wavelength spacing between the FBGs [6,7]. The central wavelength of an optical signal can easily be changed by adjusting the Bragg wavelength of the FBGs, which allows changes to the wavelength spacing between optical peaks. In our proposed tunable notch filter, we used a fixed FBG and a tunable FBG (TFBG), making the desired free spectral ranges (FSRs) with the deep notches of more than 35 dB obtainable by adjusting the wavelength spacing. PRINCIPLE OF THE FILTER OPE...

Structural integrity of solid rocket depends on the residual reactions between constituents of its composition(post cure, migration etc.), the oxygen(or anti-oxydent) in the free volume and humidity (desiccant) under the perfect sealed condition. Mechanical Properties of composite solid propellant arising from those factors are very complex. Moreover the propulsion are faced with thermal loads from diurnal & seasonal cycle till firing. In this study, the fast evaluation method of long term mechanical properties is suggested based on Thermo-Rheological Simplicity from curing oven to cool-down stage in view point of thermal stabilization. For this subject, endurance tester having temperature control capability are devised. From the results from incremental load and strain, non-linear characteristics are discussed.