A multi-wavelength Brillouin/Erbium-Ytterbium doped fiber laser which operates in the 1535 nm region is proposed and demonstrated. The system employs both linear and nonlinear gain from a 4 meter Erbium-Ytterbium doped fiber and an 8 km single mode fiber respectively to generate an optical comb with a spacing of approximately 0.084 nm. A stable output laser comb of more than 22 lines was obtained with a Brillouin pump of 2 dBm and a 1058 nm pump of 175 mW. A maximum peak power of -4.2 dBm was obtained at a wavelength of 1535.16 nm at these pump power settings while the spectral linewidth of the laser is approximately 8 Hz.

Abstract-Wide-band hybrid amplifier is theoretically proposed using a series configuration of Thulium-doped fiber amplifier (TDFA) and fiber Raman amplifier (FRA), which using the similar type of pump laser. The operating wavelength of this amplifier covers the bandwidth of entire short wavelength band (S-band) region by combining the gain spectrum of TDFA and FRA. The theoretical gain varies from 20 to 24 dB within a wavelength region from 1460 to 1525 nm and which is in a good agreement with the experimental result. The development of reliable high-power diode lasers in the 1420 nm wavelength range will make this type of wide-band hybrid amplifier an interesting candidate for S-band optical telecommunication systems.

This paper presents short wavelength operation of tunable thulium-doped mode-locked lasers with sweep ranges of 1702 to 1764 nm and 1788 to 1831 nm. This operation is realized by a combination of the partial amplified spontaneous emission suppression method, the bidirectional pumping mechanism and the nonlinear polarization rotation (NPR) technique. Lasing at emission bands lower than the 1800 nm wavelength in thulium-doped fiber lasers is achieved using mode confinement loss in a specially designed photonic crystal fiber (PCF). The enlargement of the first outer ring air holes around the core region of the PCF attenuates emissions above the cut-off wavelength and dominates the active region. This amplified spontaneous emission (ASE) suppression using our presented PCF is applied to a mode-locked laser cavity and is demonstrated to be a simple and compact solution to widely tunable all-fiber lasers.

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A new all fiber temperature sensor is proposed and demonstrated based on a pair of 1 meter erbium-doped fiber (EDF), which are respectively macro-bent and straight. The sensor has a linear normalized loss (dB) response to temperature at 6.5 mm bending radius and 1580 nm input wavelength. The main advantage of this sensor is high temperature resolution (less than 1˚C) and sensitivity (0.03 dB/• C) due to combination of temperature dependence of EDF and bending loss. The proposed silica based sensor, has the potential for wide range and high temperature applications in harsh environments.

The potential for higher spectral efficiency has increased the interest in all-optical orthogonal frequency division multiplexing (OFDM) systems. However, the sensitivity of all-optical OFDM to fiber non-linearity, which causes nonlinear phase noise, is still a major concern. In this paper, an analytical model for estimating the phase noise due to self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM) in an all-optical OFDM system is presented. The phase noise versus power, distance, and number of subcarriers is evaluated by implementing the mathematical model using Matlab. In order to verify the results, an all-optical OFDM system, that uses coupler-based inverse fast Fourier transform/fast Fourier transform without any nonlinear compensation, is demonstrated by numerical simulation. The system employs 29 subcarriers; each subcarrier is modulated by a 4-QAM or 16-QAM format with a symbol rate of 25 Gsymbol/s. The results indicate that the phase variance due to FWM is dominant over those induced by either SPM or XPM. It is also shown that the minimum phase noise occurs at -3 dBm and -1 dBm for 4-QAM and 16-QAM, respectively. Finally, the error vector magnitude (EVM) versus subcarrier power and symbol rate is quantified using both simulation and the analytical model. It turns out that both EVM results are in good agreement with each other.

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