Stable Multi-wavelength Laser Research Articles

Multiwavelength fiber laser with ultradense wavelength spacing based on inhomogeneous loss with assistance of nonlinear polarization rotation

We demonstrate a multiwavelength fiber laser with ultradense wavelength spacing and ultrabroad bandwidth based on inhomogeneous loss mechanism with assistance of nonlinear polarization rotation. The inhomogeneous loss, implemented by incorporating a section of highly nonlinear fiber (HNLF) and a Sagnac filter in the laser cavity, can balance mode competition in erbium-doped fiber and result in ultradense multiwavelength generation. The bandwidth of the multiwavelength spectrum is greatly broadened owing to the intensity-dependent loss induced by nonlinear polarization rotation. Stable multiwavelength lasing with wavelength spacing of 0.08 nm and wavelength number up to 254 is achieved at room temperature. Moreover, multiwavelength tuning is realized through modifying polarization-dependent cavity loss.

Tunable multiwavelength SOA fiber laser with ultra-narrow wavelength spacing based on nonlinear polarization rotation

A tunable multiwavelength fiber laser with ultra-narrow wavelength spacing and large wavelength number using a semiconductor optical amplifier (SOA) has been demonstrated. Intensity-dependent transmission induced by nonlinear polarization rotation in the SOA accounts for stable multiwavelength operation with wavelength spacing less than the homogenous broadening linewidth of the SOA. Stable multiwavelength lasing with wavelength spacing as small as 0.08 nm and wavelength number up to 126 is achieved at room temperature. Moreover, wavelength tuning of 20.2 nm is implemented via polarization tuning.

Multi-wavelength erbium-doped fiber ring laser based on wavelength-dependent polarization rotation with a phase modulator and an in-line comb filter

A stable room-temperature multi-wavelength erbium-doped fiber ring laser has been proposed and investigated experimentally. A phase modulator composed of a piece of fiber wrapped around a cylindrical piezoelectric transducer is used to suppress the mode competition. And the combined action between optical fiber and polarization-dependent isolator provides the wavelength-dependent loss induced by wavelength-dependent polarization rotation mechanism to flatten the output spectrum, tune the locations and improve the number of the lasing lines. Stable multi-wavelength lasing with wavelengths up to 23 and the wavelength spacing of 0.4 nm is demonstrated. Moreover, the pulse train output was also observed.

Wavelength-spacing continuously tunable multiwavelength erbium-doped fibre laser based on DSF and MZI

A novel multiwavelength erbium-doped fibre laser is proposed by incorporating a section of dispersion-shifted fibre (DSF) and a Mach-Zehnder interferometer (MZI). The wavelength spacing of the fibre laser can be continuously tuned by adjusting an optical variable delay line in the MZI-based comb filter. Stable multiwavelength lasing at room temperature with the standard ITU (International Telecommunication Union) channel spacing of 0.2 nm (25 GHz), 0.4 nm (50 GHz), 0.8 nm (100 GHz) or 1.6 nm (200 GHz) is demonstrated.

Stable multiwavelength erbium-doped fiber ring laser using self-lasing feedback

An effective approach to enhance the performance of a room-temperature multiwavelength fiber ring laser is presented. By introducing self-lasing feedback in conventional phase-modulation-based multiwavelength fiber ring lasers, the number of lasing lines is increased and the differences among the lasing lines are diminished. Stable multiwavelength lasing with numbers of lasing lines up to 17 within the 3-dB spectral bandwidth and with wavelength spacing as small as 0.2 nm is achieved.

Stable room-temperature multi-wavelength lasing realization in ordinary erbium-doped fiber loop lasers

A suppressant effect for mode competition of multi-wavelength lasing oscillations induced by deeply saturated effect in an ordinary erbium-doped fiber ring laser (EDFRL) was observed and experimentally investigated. Results show that the effect is helpful to obtain stable multi-wavelength lasing at room temperature in the EDFRL, which offers a new and simple approach to achieve stable multi-wavelength EDF lasing. Stable two- and three- wavelength lasing oscillations were achieved based on the effect in the ordinary EDFRL for the first time to our best knowledge. The multi-wavelength lasing oscillations were so stable integrated over smaller than 1 ms that the maximum power fluctuation over more than 30 minutes of observation was less than 0.1 dB and 0.5 dB for two-wavelength lasing with a spacing of 1.28 nm and 0.76 nm, respectively.

Multiwavelength peak power equalized lasers based on SOA using a sampled chirped fiber Bragg grating

A novel multiwavelength SOA ring laser and a linear cavity multiwavelength laser are proposed and demonstrated experimentally. Stable multiwavelength lasing operation with about 100 GHz channel spacing is achieved with both lasers. Up to ten stable lasing wavelengths with an OSNR greater than 40 dB are obtained with an equalized peak power. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1981–1984, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21821

Multiwavelength laser source using linear optical amplifier

We propose and demonstrate a high-performance multiwavelength ring laser based on a linear optical amplifier (LOA) for potential applications in dense wavelength-division-multiplexing communication systems. Experimental results indicate that the inhomogeneous gain medium provided by the LOA reduces the gain competition and leads to stable multiwavelength lasing. Thirty-eight wavelengths covering C+L-band with 0.8-nm channel spacing are generated at room temperature. Simultaneous tuning of multiwavelengths is demonstrated and a stability test shows a power fluctuation of less than 0.2 dB during a 3-h test.

Multiwavelength erbium-doped fiber ring laser incorporating an SOA-based phase Modulator

A novel room-temperature multiwavelength erbium-doped fiber (EDF) laser is demonstrated. Stable multiwavelength lasing at room temperature is realized by incorporating a semiconductor optical amplifier (SOA)-based phase modulator in the laser cavity. The SOA is biased below the transparent point with a sinusoidal signal applied to achieve phase modulation, to suppress the homogenous line broadening of the EDF. Stable multiwavelength lasing with wavelengths up to 26 and wavelength spacing as small as 0.19 nm is demonstrated at room temperature.

Multiwavelength erbium-doped fiber Fabry-Pe/spl acute/rot laser and its uniform spectral lines power operation

Multiwavelength erbium-doped fiber laser by means of phase modulation in a linear cavity configuration is presented. Stable multiwavelength lasing is achieved by applying any one of the waveforms of sine, square, sawtoothed, and triangular at a suitable frequency between 500 Hz to a few tens of kilohertz to the phase modulator. The output spectral lines power equalization is performed by adjusting the frequency to drive the all-fiber phase modulator and the polarization controller or dc offset voltage of a LiNbO/sub 3/ amplitude modulator, which is incorporated in a polarization-maintaining fiber Lyot-Sagnac filter.

Multiwavelength ring lasers employing semiconductor optical amplifiers as gain media

AbstractStable simultaneous multiwavelength lasing is demonstrated with a novel fiber‐ring laser incorporating a semiconductor optical amplifier. Band‐pass comb filtering is constructed in the ring cavity with the combination of a wideband Fabry–Perot comb filter and a bandpass filter. Ten lasing lines with a fixed wavelength spacing of 1.6 nm are implemented and the multiwavelength lasing ranges can be flexibly chosen. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 301–303, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20451

Multiwavelength lasers based on semiconductor optical amplifiers

Stable multiwavelength lasing is demonstrated with a novel laser, in which a semiconductor optical amplifier offers optical gain and cascaded sampled fiber gratings serve as a comb filter. Five lasing lines are obtained with a fixed wavelength spacing of 0.8 nm. Optical power fluctuations among the lasing lines are improved by adjusting the reflectivity profile through the cascade of two sampled gratings.

Room‐temperature multiwavelength operation of an elliptical core erbium‐doped fiber laser

AbstractA simple and efficient technique to achieve stable multiwavelength laser operation at room temperatures with the use of an elliptical‐core erbium‐doped fiber is proposed and demonstrated. The results give a maximum of five simultaneous laser lines in the L band. A polarization controller is used to control and select the lines. The principle of operation is based on the anisotropic gain effect in a polarization‐maintaining fiber. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 184–186, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10271

Miniature erbium:ytterbium fiber Fabry-Perot multiwavelength lasers

We demonstrate stable simultaneous lasing of up to 29 wavelengths in miniature 1- and 2-mm-long Er/sup 3+/:Yb/sup 3+/ fiber Fabry-Perot lasers. The wavelengths are separated by 0.8 (100 GHz) and 0.4 nm (50 GHz), respectively, corresponding to the free spectral range of the laser cavity. The number of lasing wavelengths and the power stability of the individual modes are greatly enhanced by cooling the laser in liquid nitrogen (77 K). The polarization modes and linewidth of each wavelength are measured with high resolution by heterodyning with a local oscillator. The homogeneous linewidth of the Er/sup 3+/:Yb/sup 3+/ fiber at 77 K is determined to be /spl sim/0.5 nm, from spectral-hole-burning measurements, which accounts for the generation of a stable multiwavelength lasing comb with wavelength separations of 0.4 nm.

VERTICAL CAVITY SURFACE EMITTING LASERS WITH DIELECTRIC MIRRORS

We have developed new low threshold surface emitting laser designs with dielectric high reflectivity top mirrors. Here, we describe the characteristics of these surface emitting vertical cavity lasers (VCSELs) which exhibit stable mode patterns and low threshold currents. The new device fabrication sequence which we employ is able to adjust the emission wavelength of the lasers during the final fabrication step and allow the development of stable multi-wavelength laser arrays. These quantum-well based laser diodes are demonstrated at 0.72 μm with threshold currents of 20 mA, at 0.85 μm with threshold currents of 3 mA, at 0.98 μm with threshold currents of 4 mA, and at 1.55 μm with threshold currents of 17 mA. Our VCSELs also display remarkably low threshold voltages, thus minimizing the laser power dissipation and improving the wallplug efficiency. The flexibility resulting from depositing one or both of the mirrors after the fabrication of the laser diodes opens the way to the development of new and more versatile laser structures.