Volume 36, Issue 4 -

New design for surface plasmon resonance (SPR) lens having a sub-wavelength size of spot in the far-field region is proposed in this work. An extra structure of concentrically annular grating fabricated on the top surface of SPR lens is utilized to improve the quality of focusing. Numerical simulation results of the novel type of SPR lenses with different grating structures are presented and compared.

In this paper, optical time division multiplexing is demonstrated using TOAD (terahertz optical asymmetric demultiplexer), which employs semiconductor optical amplifier (SOA) as nonlinear switching element. The TOAD device in its original configuration is based on Sagnac interferometer (also referred to as nonlinear optical loop mirror – NOLM).

An all-fiber linearly polarized Yb 3+ -doped double-clad fiber laser is proposed, in which the resonance cavity is composed of a pair of polarization-maintaining fiber Bragg gratings (PM-FBGs). The polarization hole burning is enhanced by the selective polarization feedback by the PM-FBGs. A three-port polarization beam splitter with fiber pigtail is inserted into the laser cavity to select different polarization states. The laser features wavelength of 1,069.72 and 1,069.98 nm, output power of 128 mW and signal-to-noise ratio (SNR) of 45 dB. The quasiphase-matched periodically poled lithium niobate (PPLN) crystal was used to obtain a frequency-doubled green laser, with a pump power of 128 mW, and a 21.9-mW output power is achieved.

In recent years optical time domain reflectometer (OTDR)-based techniques have become a known practice for measuring chromatic dispersion (CD) distribution along an optical fiber transmission link. In this paper, a measurement technique which uses a four-wavelength bidirectional OTDR to evaluate the CD distribution along the length of an optical fiber transmission system has been presented. A novel formulation has been developed for this nondestructive technique to improve the correction factor, which leads to an improvement in the CD and mode field diameter (MFD) measurement. The obtained experimental outcomes are in good agreement with those obtained by the interferometric technique.

Passive optical networks based on orthogonal frequency division multiplexing (OFDM-PON) give better performance in high-speed optical access networks. For further improvement in performance, a new architecture of OFDM-PON based on spreading code in electrical domain is proposed and analytically analyzed in this paper. This approach is referred as hybrid multi-carrier code division multiple access-passive optical network (MC-CDMA-PON). Analytical results show that at bit error rate (BER) of 10 –3 , there is 9.4 dB and 14.2 dB improvement in optical power budget for downstream and upstream, respectively, with MC-CDMA-PON system as compared to conventional OFDM-PON system for the same number of optical network units (ONUs).

In this paper, we have presented analysis of OFDM-based Radio over FSO Communication System using M-QAM Modulation under different data rate and attenuation. A distance of 1,000 m was achieved at 10 Gbit/s data rate in OFDM-based Radio over FSO Communication System.

Wavelength-division multiplexed-passive optical network (WDM-PON) is a revolutionary high-capacity and scalable broadband access network. This paper capitalizes on Laguerre–Gaussian (LG) modes to reduce modal dispersion and increase data capacity. A data rate of 25 Gbit/s is attained for a multimode fiber link by multiplexing five LG modes on five wavelengths centered at 1,550.12 nm for a distance up to 800 m.

We systematically analyze the pulse distortion resulting from polarization mode dispersion (PMD) by deriving an analytic expression for the characteristic function of the system bit error probability (BEP) density in terms of the lowest-order moments of the Fourier transformed input pulse shape. We determine the range of validity of our technique, which implements a second-order expansion of the Jones matrix, by comparing our results for chirped and unchirped input pulses with direct numerical simulations. Our method may be easily applied to analyze the role of the first- and second-order PMD in the interference between adjacent pulses.