OPTICS 2016 Abstracts


Full Papers
Paper Nr: 3
Title:

Digital Mirror Devices for Mode Selective Excitation in Multimode Fibers

Authors:

Andreas Ahrens, Steffen Lochmann and Peter Bartmann

Abstract: Space division multiplex (SDM) in optical communications became an attractive research topic in recent years. A tremendous increase of data rates was exposed. In optical multiple-input multiple-output (OMIMO) SDM can be achieved by using separated fiber cores or several modes in multimode fibers (MMF). This paper tackles the task of mode selective excitation in MMFs. A completely new approach is shown utilizing digital mirror devices (DMDs) in this field. However, finding the optimal coupling conditions is a complex task due to the blazed grated structure of the micromirror array (MMA). A possible and intuitive solution for that problem is shown. Still, the benefits of such DMDs lies in the flexibility of mode excitation and the low insertion loss of around -1.27 dB. This paper shows that the mode separation is comparative to mode excitation achieved with offset splices.

Paper Nr: 6
Title:

Evaluation of Multi-band Carrier-less Amplitude and Phase Modulation Performance for VLC under Various Pulse Shaping Filter Parameters

Authors:

Petr Chvojka, Paul Anthony Haigh, Stanislav Zvanovec, Petr Pesek and Zabih Ghassemlooy

Abstract: In multi-band carrier-less amplitude and phase modulation (m-CAP), the transmitter and receiver pulse shaping filters have a significant impact on the signal performance. Since m-CAP is an emerging and promising modulation format for visible light communications (VLC), it is necessary to balance the system performance and the filter length, due to limited integration density in field programmable gate arrays (FPGAs). In this paper we investigate the m-CAP VLC system performance for different number of sub-bands m = {2, 5, 10} under varying finite impulse response (FIR) filter parameters, such as the filter length Lf and the roll-off factor β. We show that increasing both β and Lf improves the bit error rate (BER) performance of the system substantially. We demonstrate that a BER target of 10-4 is achieved using Lf ≤ 12 symbols for m = 5 and 10 for low order subcarriers. Moreover, the BER limit is attained for β = 0.2 by all subcarriers, except the last two for m = 5 and 10, which is a significant improvement, even considering the slightly increased excess bandwidth in comparison to the literature.

Short Papers
Paper Nr: 4
Title:

Polynomial Matrix SVD Algorithms for Broadband Optical MIMO Systems

Authors:

Andreas Ahrens, Andre Sandmann, Zeliang Wang and John G. McWhirter

Abstract: Polynomial matrix singular value decomposition (PMSVD) plays a very important role in broadband multiple-input multiple-output (MIMO) systems. It can be used to decompose a broadband MIMO channel matrix in order to recover the transmitted signals corrupted by the channel interference (CI) at the receiver. In this contribution newly developed singular value decomposition (SVD) algorithm for polynomial matrices are analyzed and compared in the application of decomposing optical MIMO channels. The bit-error rate (BER) performance is evaluated and optimized by applying bit and power allocation schemes. For our simulations, the specific impulse responses of the (2x2) MIMO channel, including a 1.4 km multi-mode fiber and optical couplers at both ends, are measured for the operating wavelength of 1576 nm.

Paper Nr: 9
Title:

Long-haul Coherent Optical OFDM Point-to-Point Transmission using Optical Phase Conjugation

Authors:

Thosaphon Jaemkarnjanaloha, Rachata Maneekut and Pasu Kaewplung

Abstract: In this paper, we demonstrate the superchannel polarization division multiplexed coherent optical orthogonal frequency-division Multiplexing (PDM-CO-OFDM) system employing midway optical phase conjugation (OPC). The system is designed to show the optimum number of sub-carriers, amplifier spacing and the maximum achievement reach at data rate 1Tb/s (10x100 Gb/s). The system is simulated with 10-WDM superchannel at 50 GHz channel spacing. From the simulation results, PDM-CO-OFDM, with midway OPC and the optimum system parameters, we can achieve the maximum reachable distance of 24,000 km at BER 4x10-3.

Paper Nr: 10
Title:

Slightly Tapered Optical Fiber with Inner Air-cavity for Simultaneous Refractive Index and Temperature Sensing

Authors:

D. N. Wang, Lei Zhang, Jibing Liu and H. F. Chen

Abstract: A fiber in-line Mach-Zehnder interferometer based on inner air-cavities for simultaneous refractive index and temperature sensing is presented. The inner air-cavities are fabricated by use of femtosecond laser micromachining, fusion splicing and slightly tapering techniques. The transmission spectrum of the interferometer exhibits a number of resonance wavelength dips corresponding to different orders of cladding modes. By tracking the shift of two dip wavelengths, the changes of refractive index and temperature can be obtained by use of a matrix method. The refractive index and temperature sensitivity achieved are 103.00 nm/RIU (refractive index unit) and 73.07 pm/℃, respectively.

Paper Nr: 11
Title:

Dual-Frequency VECSEL at Telecom Wavelength for Sensing Applications

Authors:

Léa Chaccour, Guy Aubin, Kamel Merghem, Jean-Louis Oudar, Aghiad Khadour, Patrice Chatellier and Sophie Bouchoule

Abstract: We aim at realizing an optically-pumped, dual-frequency VECSEL at telecom wavelength (1.5 µm) with a frequency difference in the radio-frequency (RF) range (around 11 GHz), to be used in a sensor unit based on Brillouin scattering in optical fibers. Laser emission of two orthogonally-polarized cavity modes with a controlled frequency difference is obtained by inserting a birefringent crystal in the VECSEL cavity. We have examined the influence of the different intra-cavity elements on the laser emission. It is shown that optimizing the free spectral range and the bandwidth of the intra-cavity Fabry-Perot etalon is of practical importance to achieve a stable single longitudinal laser emission for each of the two orthogonal polarizations. The optimization of the output power has also been investigated and it is concluded that up to 100 mW output power can be expected by adjusting the reflectivity of the output coupling mirror of the VECSEL cavity. The achievement of a highly-stable frequency difference is crucial for sensing applications. For this reason the influence of different parameters on the stability of the dual-frequency emission have been studied. It is concluded that mechanical vibrations are the main cause of the RF signal instability in our free-running VECSEL cavity. The design of a compact or mono-block cavity may allow to meet the stability requirements for our sensors.

Paper Nr: 13
Title:

Optical Parametric Amplification Performance in AsSe2-based Hybrid Microstructured Optical Fibers

Authors:

Hoang Tuan Tong, Kenshiro Nagasaka, Morio Matsumoto, Hiroshige Tezuka, Takenobu Suzuki and Yasutake Ohishi

Abstract: The performance of fiber-optical parametric amplification is studied by employing the AsSe2-based hybrid microstructured optical fiber (HMOF). By adding a buffer layer around the core with appropriate diameter and refractive index difference, the chromatic dispersion profile of chalcogenide HMOFs can be tailored to have a near-zero and flattened anomalous dispersion regime in the mid-infrared window. A very broad gain bandwidth can be achieved from 3.0 to 9.0 µm by pumping at 4.7 µm. The signal gain can be as high as 32 dB. In addition, the HMOF with buffer layer can suppress the chromatic dispersion variation caused by the fiber structure fluctuation and maintain the signal gain spectrum.