Yi-Lin Yu

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We demonstrate a practical 2×80 Gbit/s dense wavelength division multiplexing (DWDM) bidirectional short-range optical wireless link. The measured power penalties for the bidirectional transmission are less than 0.8 and 0.2 dB compared to the back-to-back link and the unidirectional transmission system, respectively. We also practically evaluate the impact of the offset angles between the optical transmission path and the building windows. The result shows that the power penalty is as small as 0.3 dB. This technology offers a great potential for applications in building-to-building inter-transmission as part of local/wide area networks.

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By using a subring cavity incorporated with a saturable absorber, a stable single-frequency selection is realized in a linear-cavity fiber laser, which is constructed using a broadband fiber mirror and a partial reflectance fiber Bragg grating as the cavity ends. At 1550.33 nm, the laser has an optical signal-to-noise-ratio of >53.28 dB and with linewidth less than 1 MHz. The pumping efficiency is 25% improved by recycling the residual pump power to gain medium. The power stability and wavelength stability have also been studied.

80 Gbit/s DWDM Bidirectional Wavelength Reuse Optical Wireless Transmission

In this paper, a 10-Gb/s hybrid optical fiber (OF) and free-space optics (FSO) link as part of a bidirectional long-haul OF transmission for application in outdoor environments such as bridges is proposed. A fiber-Bragg-grating (FBG) sensor head is used for monitoring the condition of a bridge, and in the case of the bridge being damaged, the transmission path is changed over from OF to the FSO link to ensure link connectivity. An Erbium-doped fiber amplifier is used to compensate for losses due to the fiber cable and the free-space channel. At a bit error rate (BER) of 10e-9, the power penalty between the OF and FSO paths is <; 1 dB, and the power variations for both paths are ±0.07 and ±0.12 dB, respectively.

Linear-cavity fiber laser using subring-cavity incorporated saturable absorber for single-frequency operation

A hybrid fiber amplifier is a promising technology for dense wavelength division multiplexing (WDM) in multi-terabit systems. Recently, hybrid fiiber amplifiers are designed in order to maximize the span length and/or to minimize the impairments of fiber nonlinearities, and to extend the bandwidth of EDFAs

A Hybrid Optical Fiber and FSO System for Bidirectional Communications Used in Bridges

Abstract This article presents a novel bidirectional wavelength reconfigurable optical network utilizing a remotely pumped erbium-doped fiber amplifier and tunable fiber Bragg gratings. The system is experimentally demonstrated at a 10-Gb/s per channel over 20-km fiber span that verifies the metro-network range system performance. The achieved power penalty is less than 1 dB when compared to the back-to-back transmission link. An example of practical application where the proposed module is used as an add/drop multiplexer and a remote node in the bidirectional wavelength division multiplexing passive optical network system is described.

Dispersion management and gain flattened a hybrid EDFA/RFA with pumping recycling mechanism

We propose a hybrid C+L band fiber amplifier loop-back scheme which is composed of a C-band erbium-doped fiber amplifier (EDFA) and an L-band Raman fiber amplifier (RFA) using double-pass dispersion compensators in a loop-back scheme (also named as bridge scheme). Dispersion slope mismatch are precisely compensated for all 14 C+L band channels by writing fiber Bragg gratings (FBGs) at appropriate locations. Gain variation among multiple channels can be reduced from 6.5 dB to ±0.2 dB. The overall pump efficiency is 25% improved for C band signals by recycling the residual pump power. With several merits as mentioned, the hybrid EDFA/RFA may find potential applications in WDM long-haul systems and optical networks.

Bidirectional Wavelength Reconfigurable Module Based on Tunable Fiber Bragg Grating and Remote Pump Amplifier

We propose two kinds of simple frequency detection methods. One consists of cascaded AWGs with different frequency intervals. The other consists of frequency-shifted two kinds of A WGs and a post processing circuit.

Dispersion management and gain flattened for a bridge-type hybrid amplifiers in a pumping recycling mechanism

A multi-point temperature sensing system using linear-cavity laser consisting of a semiconductor optical amplifier, an arrayed waveguide grating, and fiber Bragg grating elements was proposed. We experimentally demonstrated two-point simultaneous temperature sensing.

High-resolution frequency detection with multiple AWGs and post-processing for multi-channel fiber sensors

A multi-point fiber sensing system formed from a linear cavity laser is proposed. Various optical sensing systems have been investigated, for example, using fiber Bragg grating (FBG) and Brillouin scattering for multi-point sensing. This paper focuses on a simple sensing system by using multi-wavelength lasing with parallel cavities and a semiconductor optical amplifier (SOA). First, optical nonlinearity in amplification of the SOA is discussed to clarify the effects of gain saturation and four-wave mixing on the proposed multi-channel sensing system. And then lasing conditions in the linear cavity laser consisting of an SOA, an arrayed waveguide grating (AWG), and FBGs are theoretically investigated. The multi-wavelength lasing power is found to be limited mainly by gain saturation in the SOA. The lasing power for the eight-channel system is evaluated to be -8.5  dBm when the total loss in the linear cavity is 10 dB. The lasing power can be increased by 3 dB when the channel number is decreased to four. Next, multi-wavelength lasing in the cavity consisting of an SOA, an AWG, a loop mirror, and fiber mirror reflectors is experimentally demonstrated up to eight channels. Finally, two-channel temperature sensing ranging from 13°C to 76°C is experimentally confirmed by using two FBGs as the sensing elements with an AWG having 100-GHz bandwidth.

Multipoint temperature sensing using linear-cavity fiber laser with AWG and FBGs

A high-power Erbium/Ytterbium co-doped fiber amplifier (EYDFA) is designed, investigated. The signal gain and noise figure characteristics are studied. Also, a C-band Erbium doped fiber laser is proposed and investigated. The characteristics of fiber ring laser are measured and discussed.