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Metamaterials (MMs) are artificial media tailoring the propagation of light by a design of a unit cell (meta-atom, MA). There is the evident inclination in favor of numerical methods in the description of the optical properties of MMs at the expense of physical intuition. It is shown that complementary to the numerical ones, qualitative models can provide a deeper understanding of the basic physical processes. The phenomenological approach to the homogenization resulted in three possible representations of Maxwell equations: Casimir, Landau–Lifshitz, and new toroidal ones. The multipole approach has been formulated and extended to the case of coupling between MAs, including random MA positioning. It has been shown that the quadrupole moment inherently introduces nonlinear (second-order) material response. The multipole approach has been applied for the case of the quantum MM to the coupled carbon nanotubes, and for the case of MAs to regular and stochastic properties of the nanolaser (spaser), and monochromatic plane wave propagation in the MM consisting of nanolasers.

A novel bidirectional ultra-wideband over-fiber (UWBoF) system compatible with the wavelength-division-multiplexing (WDM) architecture is presented. In the proposed scheme, a 6th order Gaussian derivative is generated for UWB transmission in a downstream (DS) scenario, based on the directly modulated laser, accumulative chromatic dispersion in the transmission fiber and delay-line-interferometer (DLI). While the UWB signal is received from one of the DLI outputs, the other output is utilized to reuse the wavelength by injection locking a colorless Fabry-Perot laser diode (FP-LD). Due to the filtering effect of the FP-LD, a clear optical carrier without intensity modulation is then generated which can be used for upstream (US) baseband (BB) transmission by directly modulating the FP-LD. In order to eliminate the unwanted Rayleigh scattering induced noise in the bidirectional transmission, a dual - fiber transmission architecture is used. The principle of operation is explained. A symmetric transmission of 1.25 Gbps UWB over 60 km single mode fiber (SMF) is performed. Bit-error-rate (BER) measurements and eye diagrams for both down and upstream transmissions are presented.

A novel and cost-efficient technique is presented to generate non-return-to-zero (NRZ) and ultra-wideband (UWB) signals in different time slots of time division multiplexing-passive optical network (TDM-PON) by using a single chirped controlled semiconductor laser associated with an optical bandpass filter. In this technique, the chirp of the laser is controlled by different bias burst amplitudes (BBA) for different time slots. Through the proper selection of the burst amplitudes, 10 Gbps NRZ and 1.25 Gbps UWB signals are generated in different time slots. Principle of operation is discussed, the complete chirp behavior of the laser is experimentally investigated, data transmission of the generated signals is demonstrated and bit-error-rate (BER) level of 10-sup9/supis achieved.

We report an electrically pumped 1550 nm MEMS tunable VCSEL with a continuous tuning of 101 nm at 22 °C. The top MEMS-DBR with built-in stress gradient within the dielectric layers is deposited in a low-temperature PECVD chamber on an InP-based half-VCSEL, structured by surface-micromachining and electrothermally actuated for continuous wavelength tuning. With 2.6 mA threshold current, the laser shows maximum CW output power of 3.2 mW at 1560 nm. The MEMS-VCSEL operates in single-mode with SMSR > 39 dB across the entire tuning range. At 36 °C, the tuning range reaches up to 107 nm. The divergence angle of the MEMS-VCSEL is approximately 5.6° for all tuning wavelengths. The intrinsic linewidth of an unpackaged device is 21 MHz. Quasi-error-free operation at 12.5 Gbps using a directly modulated MEMS-VCSEL is reported for a record 60 nm tuning, showing the potential of the so-called colorless source in WDM applications.

Several Applications for tunable laser diodes have strict constraints in terms of overall power consumption. Furthermore, the implementation in harsh environments with large temperature fluctuations is necessary. Due to the constraint in power consumption, the application of active cooling might not be an option. For this reason we investigate the temperature characteristics of an electrically pumped MEMS-VCSEL with wide continuous wavelength tuning. For the first time, a mode hop free single mode (side mode suppression ratio (SMSR) > 40dB) tuning range of 45nm at 70°C is demonstrated with a MEMS-VCSEL. An increase of the tuning range from 85nm at 20°C to 92nm at 40°C is measured and explained. In contrast to fixed wavelength VCSEL, the investigated device shows a negative temperature induced wavelength shift of -4.5nmK(-1), which is caused by the MEMS-mirror. At 1560nm, the fibre-coupled optical output power is above 0.6mW over the entire temperature range between 20°C to 70°C and shows a maximum of > 3mW at 20°C.

The future information infrastructure will be affected by limited bandwidth of optical networks, high energy consumption, heterogeneity of network segments, and security issues. As a solution to all problems, we advocate the use of both electrical basis functions (orthogonal prolate spheroidal basis functions) and optical basis functions, implemented as FBGs with orthogonal impulse response in addition to spatial modes. We design the Bragg gratings with orthogonal impulse responses by means of discrete layer peeling algorithm. The target impulse responses belong to the class of discrete prolate spheroidal sequences, which are mutually orthogonal regardless of the sequence order, while occupying the fixed bandwidth. We then design the corresponding encoders and decoders suitable for all-optical encryption, optical CDMA, optical steganography, and orthogonal-division multiplexing (ODM). Finally, we propose the spectral multiplexing-ODM-spatial multiplexing scheme enabling beyond 10 Pb/s serial optical transport networks.

This paper proposes the use of chirp-managed lasers (CML) as cost-effective downstream (DS) transmitters for next generation access networks. As the laser bandwidth is as high as 10 GHz, the CML could be directly modulated at 10 Gbit/s for downstream transmission in future wavelength division multiplexing passive optical networks (WDM PON). The laser adiabatic chirp, which is the main drawback limiting the transmission performance of directly modulated lasers, is now utilized to generate phase-shift keying (PSK) modulation format by direct modulation. At the user premise, the wavelength reuse technique based on reflective colorless upstream transmitter is applied. The optical network unit (ONU) reflects and orthogonally remodulates the received light with upstream data. A full-duplex transmission with symmetrical 10-Gbit/s bandwidth is demonstrated. Bit-error-rate measurement showed that optical power budgets of 29 dB at BER of 10(-9) or of 36 dB at BER of 10(-3) could be obtained with direct phase-shift-keying modulation of CML which proves that the proposed solution is a viable candidate for future WDM-PONs.