Showing papers by "Bing Sun published in 2017"

26 m/5.5 Gbps air-water optical wireless communication based on an OFDM-modulated 520-nm laser diode

Abstract: We experimentally demonstrate a high-speed air-water optical wireless communication system with both downlink and uplink transmission employing 32-quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) and a single-mode pigtailed green-light laser diode (LD). This work is an important step towards the future study on optical wireless communications between underwater platforms and airborne terminals. Over a 5-m air channel and a 21-m water channel, we achieve a 5.3-Gbps transmission without power loading (PL) and a 5.5-Gbps transmission with PL in the downlink. The corresponding bit error rates (BERs) are 2.64×10-3 and 2.47×10-3, respectively, which are below the forward error correction (FEC) criterion. A data rate of 5.5 Gbps with PL at a BER of 2.92×10-3 is also achieved in the uplink.

An Injection-Locked Single-Longitudinal-Mode Fiber Ring Laser With Cylindrical Vector Beam Emission

Abstract: We demonstrate a fiber ring laser with narrow bandwidth single-longitudinal-mode cylindrical vector beam (CVB) output at C-band wavelength range for the first time to the best of our knowledge. A step index two-mode fiber Bragg grating is used as a transverse mode selector for CVB generation, while both the injection-locking technique and narrow bandwidth of the fiber Bragg grating lead to single-longitudinal-mode operation. The 3-dB bandwidth of the laser output is measured to be 60 dB. Mode distribution and optical spectra of few-mode fibers with periodic modulated refractive index profile, namely the few-mode fiber Bragg gratings with bent radius, are investigated theoretically and experimentally, which provide a comprehensive exploration of CVB's generation.

Automatic Arc Discharge-Induced Helical Long Period Fiber Gratings and Its Sensing Applications

Abstract: We experimentally demonstrate an automatic arc discharge technology for inscribing high-quality helically twisted long period fiber gratings (H-LPFGs) with greatly improved inscription efficiency for single mode fibers. The proposed technology has been developed by implementing an embedded program in a commercial fusion splicer, which employs an ultraprecision motorized translation stage while the tensioning mass required by conventional inscribing technology is eliminated. More significantly, the arc-induced H-LPFGs have been reported to have potential usage as sensors in temperature, refractive index, twist stress, and strain.

Mode selection coupler based 8-shaped cavity mode locking column vector fiber laser

Abstract: The invention discloses a mode selection coupler based 8-shaped cavity mode locking column vector fiber laser including a pump source, a wavelength division multiplexer, a gain fiber, a single-mode fiber, a first polarization controller, a second polarization controller, a 3dB coupler, an isolator, a coupler and a mode selection coupler. The output terminal of the pump source is connected with a short wavelength input terminal of the wavelength division multiplexer. The output terminal of the wavelength division multiplexer is connected with a 1 port input terminal of the 3dB coupler through the gain fiber, the single-mode fiber and the first polarization controller successively. A 2 port input terminal of the 3dB coupler is connected with a long wavelength port of the wavelength division multiplexer. A 4 port is connected with a 3 port of the 3dB coupler through the isolator, the coupler and the mode selection coupler successively. Therefore, an 8-shaped resonance cavity is formed. The second polarization controller is connected with a less-mode fiber output terminal of the mode selection coupler. The invention has advantages of being narrow in fiber laser output pulses, high in column vector laser polarization purity, small in loss and low in cost.

Single-frequency narrow-band optical fiber laser based on high roundness three-dimensional rotational symmetric microcavity

Abstract: The invention discloses a single-frequency narrow-band optical fiber laser based on a high roundness three-dimensional rotational symmetric microcavity. The laser comprises a semiconductor laser pumping source, a wavelength division multiplexer, an optical isolator, a rare earth doped fiber, a polarization controller, an optical coupler and a high roundness microballoon cavity-conical fiber coupling unit. The semiconductor laser pumping source is connected with the optical isolator through the wavelength division multiplexer, and is connected with the rare earth doped fiber through the output end of the optical isolator. The output end of the rare earth doped fiber passes through the polarization controller, the high roundness microballoon cavity-conical fiber coupling unit and the optical coupler in order, and finally is connected with the input end of the wavelength division multiplexer through the output end of the optical coupler to form a closed cavity. According to the invention, high roundness microballoon cavity-conical fiber coupling unit is used to select the frequency; through ultra-narrow bandwidth echo wall mold resonance spectrum formed in the high roundness microballoon cavity, the output laser has the advantages of ultra-narrow bandwidth; and the laser has the advantages of great coherence, high stability, compact structure, low cost, small loss and the like.

Single longitudinal mode narrow-band optical fiber laser based on mode selection of optical fiber coupling double-microcavity

Abstract: The invention discloses a single longitudinal mode narrow-band optical fiber laser based on mode selection of an optical fiber coupling double-microcavity. The optical fiber laser system comprises a semiconductor laser pump source, a wavelength division multiplexer, a rare earth doping optical fiber, an optical fiber isolator, an N*N port optical fiber coupler, a polarization controller and an optical fiber coupling double-microcavity, and is characterized in that each unit are connected end to end through optical fiber coupling in a closed manner so as to form an optical fiber resonant cavity; two microcavities are respectively arranged at two sides of a tapered optical fiber and connected in parallel so as to form the optical fiber coupling double-microcavity; light gets into the double-microcavity from one end of the tapered optical fiber, is transmitted in the microcavity in a total-reflection mode so as to form narrow-band whispering gallery mode resonance, then outputted from the other end of the tapered optical fiber and connected to optical fiber resonant sub-cavities; and the optical fiber coupling double-microcavity is enabled to act as a narrow-band mode selection unit in the optical fiber resonant cavity. Compared with a single microcavity, the single longitudinal mode narrow-band optical fiber laser has the characteristics of high side-mode suppression ratio, good monochromatic property, all optical fiber, compact structure and the like.

8 word chamber mode locking post vector fiber laser based on model selection coupler

Abstract: The utility model discloses a 8 word chamber mode locking post vector fiber laser based on model selection coupler, including pumping source, wavelength division multiplexer, gain fibre, single mode fiber, a polarization controller, the 2nd polarization controller, 3dB coupler, isolator, coupler and model selection coupler, the output of pumping source links to each other with short wavelength's input of wavelength division multiplexer, wavelength division multiplexer's output loops through the gain fibre, single mode fiber, a polarization controller links to each other with the 1 port input end of 3dB coupler, the 2 port input end of 3dB coupler and long wavelength's port of wavelength division multiplexer link to each other, 4 ports of 3dB coupler pass through the isolator, the coupler, the model selection coupler links to each other with 3 ports of 3dB coupler, constitute one 8 word resonant cavity, the 2nd polarization controller is connected to few mould fibre output of model selection coupler. The utility model has the advantages of fiber laser output pulse is narrow, post vector laser polarization purity high, the loss is little, with low costs.

Determination of Optical Fiber Parameters Based On Fiber Gratings and a Search Procedure

Abstract: We demonstrated a new method to determine the optical fiber parameters using long-period fiber gratings and a search procedure. The gratings with different pitches were inscribed to measure experimental phase-matching curves. The theoretical phase-matching curves were found by calculating the effective refractive indices of fiber modes. In the search procedure, the optical fiber parameters were varied in order to minimize the difference between the experimental phase-matching curves and the theoretical ones. The optical fiber parameters were finally determined as long as the smallest difference value was reached.

Single -frequency narrowband fiber laser based on high circularity 3D rotation symmetry microcavity

Abstract: The utility model discloses a single -frequency narrowband fiber laser based on high circularity 3D rotation symmetry microcavity, include: the semiconductor laser pumping source, wavelength division multiplexer, optical isolator, the tombarthite doped fiber, polarization controller and optical coupler, still include high circularity microballon chamber tapered fiber coupling unit, the semiconductor laser pumping source links to each other with optical isolator through wavelength division multiplexer, and link to each other with the tombarthite doped fiber through optical isolator's output, the output of tombarthite doped fiber loops through polarization controller, high circularity microballon chamber tapered fiber coupling unit, a wavelength division multiplexer, synthetic chamber is closed to last being linked to each other with the wavelength division multiplexer input by the optical coupler output. The utility model discloses a high circularity microballon chamber tapered fiber coupling unit carries out the frequency -selecting, and the super narrow bandwidth echo wall mould resonance register for easy reference that high circularity microballon intracavity formed makes output laser have the advantage of super narrow bandwidth, has still that the coherence is good, stability height, compact structure, with low costs a, advantage such as the loss is little.

A novel microfiber refractometric sensor fabricated with tapering-twisting-tapering technique

Abstract: In this paper, a novel microfiber refractive index sensor prepared with tapering-twisting-tapering technique has been proposed and demonstrated for the first time. Experimental results show that the interference intensity of the novel microfiber increases with the increment of pre-tapered length and the intervening twist number. Furthermore, the refractive index sensitivity of this microfiber sensor can reach to ∼809 nm/refractive index unit (RIU) in the refractive index ranging from 1.30 to 1.33. Taking advantages of its tiny size, easy preparation and flexible design, the novel microfiber has great potential application in refractive index sensing.

All-fiber fused-type mode selective coupler with high performance and free of pre-tapering

Abstract: In this paper we propose and demonstrate a novel all-fiber fused-type mode selective coupler (MSC) that capable of converting LP01 mode to LP11 mode with high efficiency and purity. Unlike other coupler fabrication techniques for which single mode fiber (or few mode fiber) must be pre-tapered, the advantage of our proposed coupler is that pre-tapering is not required. Two different fibers of the MSC have the same diameter. We achieve LP11 mode with a high modal purity of > 90% and a coupling efficiency of >20%, with a low insertion loss of about 0.3 dB at the wavelength of 1064 nm.

A single-longitudinal-mode, narrow linewidth fiber ring laser stabilized by taper-coupled double-microsphere-cavities

Abstract: This paper proposes a novel fiber ring laser utilizing taper-coupled double-microsphere-cavities (TC-DMC) to stabilize its single-longitudinal-mode operating with a 0.01 nm narrow bandwidth. Fundamental properties including whispery gallery mode (WGM) mode distribution and transmission spectra in the DMC are investigated both theoretically and experimentally. Due to Vernier effect, the WGM spectrum of the DMC has a narrower FWHM which is compressed about 29.3% and the FSR is increased about 5.3%, as compared to the single-microsphere cavity. A 1.5 μm wavelength single-longitudinal-mode fiber ring laser with a bandwidth of 0.01 nm is also demonstrated using the taper-coupled double-microsphere-cavities (TC-DMC) as the all-fiber mode selector.

A mode-locked fiber laser generating high purity cylindrical vector beams based on a mode selective coupler in a figure-8 cavity

Abstract: We propose and demonstrate an all-fiber passively mode-locked laser with pulsed cylindrical vector beam output based on a mode selective coupler (MSC) in a figure-8 cavity, The MSC made of a two mode fiber and a standard single mode fiber is used as both the intracavity transverse mode converter and mode splitter. Through adjusting the polarization state in the laser cavity, both radially and azimuthally polarized beams have been obtained with high mode purity which are measured to be > 94%. The mode-locked laser pulses have duration of 17 ns and a repetition rate of 0.66 MHz, operating near a wavelength of 1556.3 nm with a spectral bandwidth of 3.2 nm.

Ultrasensitive refractive index sensor based on graphene coated hollow core fiber

Abstract: A high-quality nanolayer graphene (NLG) coated hollow core fiber (HCF) platform has been demonstrated for accurate monitoring of refractive index (RI) changes so far mainly operate in liquids but not in air. The NLG with high index is deposited on the outer surface of the HCF, and an enhanced anti-resonant reflecting guidance is formed, which induces sharp periodic lossy dips in the transmission spectrum. A cute experiment conducted interrogating the transmission intensity of the lossy dip demonstrates a high resolution of 2.73×10−6 RIU and a sensitivity of −365.9 dB/RIU, which is two or three times higher than that of intensity-modulated RI sensors reported previously. We believe that this configuration opens research directions for highly sensitive sensing in researches of chemistry, medicine, and biology.