Biqiang Jiang, Yueguo Hou, Jiexing Wu, Yuxin Ma, Xuetao Gan, Jianlin Zhao. In-fiber photoelectric device based on graphene-coated tilted fiber grating[J]. Opto-Electronic Science, 2023, 2(6): 230012

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- Opto-Electronic Science
- Vol. 2, Issue 6, 230012 (2023)

Fig. 1. (a ) Schematic of the configuration and operation principle of the graphene-coated TFBG integrated with a pair of electrodes. (b ) Experimental arrangement for measuring the transmission spectrum and photoelectric conversion performance of the TFBG device. BBS, broadband light source; PC, polarization controller; EDFA, Erbium-doped fiber amplifier; OSA, optical spectrum analyzer.

Fig. 2. (a ) Preparation process of the graphene-coated TFBG device and determination of orientations of gold-coating and grating planes. (b ) Diffraction fringes at a three-dimensional space, showing the weak and strong evanescent fields at two orthogonal directions, respectively. (c ) Optical microscopic images of the device under bright-field, there is the junction of uncoated and coated region between the two electrodes. (d ) Raman spectrum of the transferred graphene layer, the G mode is at 1593.19 cm−1.

Fig. 3. (a ) Polarized transmission spectra of the TFBG before and after graphene coating. (b , c ) Simulated electric field distributions of the selected P-polarized and S-polarized cladding modes of the graphene-coated TFBG. (d ) Electric field intensity of P-polarized and S-polarized modes along the fiber radial. The inset shows the intensity distributions of the 25th-order cladding modes near the boundary between fiber and graphene layer. (e ) Enlarged transmission spectra before and after graphene coating.

Fig. 4. Photoelectric response of the graphene-coated TFBG device. (a , b ) Dependence of photocurrent on the power absorbed by graphene with P-polarized light pump under applied bias voltages of 0.1, 0.2 and 0.3 V, and (c ) photoelectric responsivity of the device changing with the incident power at a bias voltage of 0.3 V. The inset of (b) shows the linear power-dependence of photocurrent in the low-power case. The inset of (c) shows the operation mechanism of electron-hole pair excitation in graphene in weak light (left) and saturated absorption (right). (d –f ) Power-dependence and responsivity of the photocurrent for the case of S-polarized light pump.

Fig. 5. (a ) Wavelength dependence (blue solid-line) of the photocurrent, which is well-matched with the transmission (red dashed-line) of TFBG scanned with a TL and measured with a commercial photodetector. (b ) Temporal response of TFBG-based photodetector. (c ) Temporal responses of the photodetector at different applied voltages with a fixed light power.

Fig. 6. (a ) Transmission spectrum of the graphene-coated TFBG. (b ) Spectral shift of one (Dip A) of the cladding modes with the increase of current. (c ) Wavelength shift versus the square of current. (d ) Measured transmission spectra of the TFBG without (red) and with (blue) the electrical injection of 2.85 mA, and the spectrum of a switching signal light. (e ) Temporal response of the “electric-optical” switching effect. (f ) Enlarged temporal response over a period with a rise/fall time of 148 ms/56 ms.

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