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Near-Infrared Indoor Optical Wireless Communications
Published in Ke Wang, Indoor Infrared Optical Wireless Communications, 2019
To achieve the same SNR in the system with free-space transmission, a larger received optical power is required due to the existence of additional background light-induced noise. Here we define the difference in the required received optical power to achieve the same system SNR as the power penalty due to background light-induced noise, and it can be calculated from Eqs. (2.41) and (2.43) as [22]: () Power−Penalty(dB)=5×log10σpr2+σbn2σpr2
Erbium-Doped Fibre Lasers
Published in Shyamal Bhadra, Ajoy Ghatak, Guided Wave Optics and Photonic Devices, 2017
Aditi Ghosh, Deepa Venkitesh, R. Vijaya
On the other hand, the ring cavity is the most common type of EDFL configuration [13,33,36–39] due to its ease of construction and absence of spatial hole burning. The schematic configuration of an EDFRL is shown in Figure 7.4. It consists of a suitable length of EDF, pumped by a semiconductor laser diode operating at 980 nm. WDMs at either end of the EDF are used to couple the pump power into and out of the cavity. A fraction R of the output power from the fibre is fed back to the input through a directional coupler to complete the ring cavity structure. The remaining fraction (1−R) is tapped out of the cavity, and the spectral characteristics of the output are observed on an optical spectrum analyser (OSA). The output power is measured using an optical power meter. Additional fibre-optic components, such as a polarizer, may be introduced at the positions marked A and B.
Research for the influence of light transmissivity of air humidity in fixed distance
Published in Ai Sheng, Energy, Environment and Green Building Materials, 2015
Y.N. Wu, Z.J. You, J.N. Ma, L. Chen
Optical power is the work done by light in a unit time. The reflection and refraction of light through different media enable energy dissipation and light power to decrease. Water fog is composed by small water droplets floating in the air. Diffuse reflection and refraction occurs between the water droplets when the light penetrates the fog. This experiment uses the characteristic to study the blocking effect of air humidity on optical power. To prevent water droplets condensed by moisture on the glass surface from affecting the experimental results, a layer of hydrophobic membrane should be present on the inner wall of the container that is going to be measured.
Spectrochemical Analytical Follow up of Phytoremediation of Oil-Contaminated Soil
Published in Soil and Sediment Contamination: An International Journal, 2018
Manar Hassan, Mahmoud Abdelhamid, Olodia Aied Nassef, Mohamed Abdel Harith
The LICF excitation source was an Argon ion laser (American laser company USA- ARJ- MED. INC, Class 3b) at the wavelength of 488 nm. The 13 mW-laser beam power is measured using an optical power-meter (JODON company model PM- 450B). A first surface plane mirror is used for directing the beam into the optical fibre which is used to bring the laser beam onto the sample surface and to collect the emitted fluorescence to feed it to the spectrometer (Ocean Optics-USB2000 FLG). An optical high pass filter (OG515- Melles Griot) is placed in front of the spectrograph entrance slit during the excitation by the argon laser to suppress any scattered laser light below 500 nm. Acquisition of the spectra is accomplished using the commercial Spectra-Suit software. All spectra are saved and analyzed using Origin software (Origin Lab. Corp., Ver. 7, USA) as performed in a previous work (Hassan et al., 2011).
Ultra-short pulse generating in erbium-doped fiber laser cavity with 8-Hydroxyquinolino cadmium chloride hydrate (8-HQCdCl2H2O) saturable absorber
Published in Journal of Modern Optics, 2021
Mustafa Mohammed Najm, Hamzah Arof, Bilal Nizamani, Ahmed Shakir Al-Hiti, Pei Zhang, Moh Yasin, Sulaiman Wadi Harun
Figure 4 shows the proposed EDFL cavity used to achieve mode-locked pulse generation using the newly developed 8-HQCdCl2H2O thin film as a SA. A 980 nm laser diode is used to pump an Erbium-doped fiber (EDF) inside the ring resonator consisting of an optical isolator, SA device and output coupler via a wavelength division multiplexing (WDM) coupler. The cavity length was about 3 m without the additional single-mode fiber (SMF). The EDF used is 1 m long which has ion absorption of 23 dB/m at 980 nm, with group velocity dispersion (GVD) of 27.6 ps2/km. The 10% output was extracted using 90/10 output coupler. A small piece of 8-HQCdCl2H2O thin-film was placed inside the cavity as an SA. The radio frequency spectrum analyzer (RFSA) (Anritsu: MS2683A) having bandwidth of 7.8 GHz, and oscilloscope (GWINSTEK: GDS-3352) having 350 MHz bandwidth were connected via a fast photodetector of (Thorlabs: DET01CFC). Optical Power Meter (OPM) (Thorlabs: PM100D) was used to report the average output power. OSA (MS9710C), Oscilloscope and RFSA were used to measure the output of laser wavelength, the resulting pulse train, and radio-frequency spectrum, respectively. The mode-locked EDFL operation was achieved by incorporating three different lengths of single-mode fiber (SMF) with GVD of −21.7 ps2/km. The length of EDFL cavity was extended with the addition of 30 m, 50 m, and 100 m SMF to design three different cases of mode locked EDFL cavity. The total length of each case for mode-locked EDFL cavity becomes 33 m, 53 m, and 103 m, with group delay dispersion (GDD) of −0.6802 ps2, −1.1142 ps2 and −2.1992 ps2, respectively. The addition of SMF also increased the cavity nonlinearity, which functions to balance the dispersion and nonlinearity characteristics of the cavity and assists in soliton pulse generation.