Switchable multi-wavelength erbium-doped fiber lasers by using cascaded fiber Bragg gratings written in high birefringence fiber

Continuous-wave silica-based erbium-doped fibre lasers

In this letter, we propose and demonstrate a simple and novel technique to get multiwavelength operation in the L-band by using an elliptical core erbium-doped fiber. The principle of operation is based on the anisotropic gain effect in a polarization-maintaining fiber. Stable multiwavelength operation is achieved at room temperatures. The lasing lines may be controlled by a polarization controller.

L-band multiwavelength fiber laser using an elliptical fiber

A multisegment all-PM fiber ring laser is constructed to demonstrate a tunable dual-wavelength laser source with continuous tuning in absolute wavelength and discrete tuning in wavelength spacing. The tuning method is based on birefringence filtering properties of a segmented all-PM fiber ring resonator. Using this method, we show a discrete wavelength spacing of dual-wavelength output from 0.9 to 2.5 nm, and continuous wavelength tuning over a few nanometers. The demonstrated dual-wavelength laser can be easily modified to tune over a greater wavelength spacing and absolute wavelength range.

Tunable dual-wavelength all-PM fiber ring laser

Sapphire, garnet and vanadate crystals are the most prominent optical materials, and vanadates play important roles in optics, especially in lasers and nonlinear optics. Neodymium-doped yttrium vanadate (Nd:YVO4) is representative and available commercially. Based on Nd:YVO4, several vanadate crystals are being developed with the goal of fulfilling the need for differential applications and improvement of certain operational aspects, such as with pulsed lasers or high-power continuous-wave lasers. In recent years, some important effects, including energy enhancement, bistability of output performance, self-Raman frequency shifting, etc., and some novel applications, such as quantum optics, pulsed lasers modulated by the two-dimensional crystals, etc., have been discovered with vanadates as gain materials. In this paper, the preparation, characterization and laser applications of vanadate laser crystals at the lasing wavelength of 1 micrometer, including YVO4, GdVO4, LuVO4, GdxY1–xVO4 and LuxGd1–xVO4 (0 < x < 1) doped with Nd3+ and ytterbium (Yb3+) are systematically reviewed by highlighting the most recent research progress. Their specific properties are presented, generation mechanisms of novel physical effects are discussed, new applications are given and possible future applications proposed by focusing on some potential strengths.

Advances in vanadate laser crystals at a lasing wavelength of 1 micrometer

Eight-wavelength Er-doped fiber lasers with lasing wavelength separations of ∼1.6 and ∼0.8 nm, respectively, have been achieved by use of overlap-written fiber Bragg gratings (OWFBG’s) in the fiber lasers and by cooling of the Er-doped fiber with liquid N2. Our experiment shows that by utilizing the OWFBG’s to select the lasing wavelengths one can achieve fiber lasers with lasing wavelengths and lasing wavelength separations that match the International Telecommunication Union channel-allocation grid well.

Multiwavelength erbium-doped fiber ring lasers with overlap-written fiber Bragg gratings.

This paper demonstrates a novel dual-period fiber grating sensor which can measure strain and temperature simultaneously. The dual-period fiber grating consists of a long-period fiber grating (LPG) and a fiber Bragg grating (FBG) which are written in the same section of an uncovered hydrogen-loaded fiber orderly. As is known, the Bragg wavelength of LPG and that of FBG have the different sensitivity of strain and temperature, then strain and temperature can be determined simultaneously by measuring the two transmitted Bragg wavelengths of the dual-period fiber grating. The accuracy of the sensor in measuring strain and temperature is estimated to be +/- 16 (mu) (epsilon) in a range from 0 to 1700 (mu) (epsilon) and +/- 0.8 degree(s)C from 20 to 120 degree(s)C, respectively.

Simultaneous measurement of strain and temperature using dual-period fiber grating

A novel method utilizing a cantilever beam to tune the center wavelength and the linear chirp of fiber gratings is presented. Based on this method, the center wavelength and the chirp of a 10 cm uniform fiber grating are tuned to compensate for the dispersion of 19 ps pulse width after 133 km transmission. Experimental results show that the effect of dispersion compensation is favorable.

Dispersion compensation experiment on 19 ps pulse width over 133 km single mode fiber with tunable chirp and wavelength gratings

Connecting an input port and an output port of a single-mode fiber coupler to form a fiber-loop, and making the time delay of the fiber-loop odd multiple of the half-period of the input optical pulse stream, we can obtain a pulse stream with multiplying repetition rate at the other output port of the coupler Utilizing three loop-connecting fiber couplers cascaded, a pulse stream with eight times the repetition rate is achieved

A novel scheme for optical pulse multiplication using fiber coupler loop-connecting configuration

Using a cantilever beam tuning device to chirp a uniform fiber Bragg grating(FBG) into a chirped one is carried out in this paper. The device developed in our laboratory can adjust the chirp constant and the center wavelength of a chirped FBG at the same time. The chirped FBG obtained in this way has been used for standard single mode nondispersion shifted fiber(NDSF) dispersion compensation in optical communication system. The principle and experimental results about chirping and dispersion compensation are presented.

Yucheng Zhao

Papers

Multiwavelength erbium-doped fiber ring lasers with overlap-written fiber Bragg gratings.

Simultaneous measurement of strain and temperature using dual-period fiber grating

Dispersion compensation experiment on 19 ps pulse width over 133 km single mode fiber with tunable chirp and wavelength gratings

A novel scheme for optical pulse multiplication using fiber coupler loop-connecting configuration

Uniform fiber Bragg grating chirp tuning and its application in dispersion compensation