Ultra-narrow Wavelength Spacing Research Articles

Multi-Wavelength SOA Fiber Laser With Ultra-Narrow Wavelength Spacing Based on NPR Effect

A multi-wavelength semiconductor optical amplifier (SOA) fiber laser with ultra-narrow wavelength spacing is experimentally demonstrated in this paper. The SOA is used as the primary gain medium due to its inhomogeneous broadening and nonlinear polarization rotation (NPR) effect that allows to achieve stable multi-wavelength output with ultra-narrow wavelength spacing. The combination of PC (polarization controller)-SOA-PC-polarizer and nonlinear optical loop mirror (NOLM) serve as the intensity equalizer for inducing IDL to suppress mode competition effect furtherly, while the NOLM mainly achieves power equalization and improve SMSR in this laser. The Lyot-Sagnac loop mirror is designed to realize different channel spacing, when the length of PMF is 71 m, stable multi-wavelength output has been achieved at room temperature. The number of lasing lines is up to 184 with wavelength spacing of 0.08 nm within 10 dB bandwidth from 1549.75 nm to 1664.25 nm, and all peaks experience some minor power fluctuation, and the maximum value is about 5 dB. The side mode suppression ratio (SMSR) is about up to 22 dB. Moreover, the maximum value of optical signal-to-noise ratios (OSNR) is 10.7 dB.

Wavelength-number-tunable multi-wavelength SOA fiber laser based on NPR effect

Abstract A wavelength-number-tunable multi-wavelength SOA fiber laser incorporating a double pass Mach–Zehnder interferometer (MZI) is experimentally demonstrated in this paper. Due to the nonlinear polarization rotation (NPR) effect of SOA, the intensity-dependent loss (IDL) is induced by the combination consisting of SOA and polarization devices to achieve stable multiwavelength output with ultra-narrow wavelength spacing. In addition, the degree of IDL can be controlled by adjusting PCs for the purpose of tuning the number of wavelengths. Stable multiwavelength output with power equality have been achieved at room temperature, which have no obvious power fluctuation. The wavelength spacing is ultra-narrow, which is as small as 0.081 nm, and the number of lasing lines is tuned from 168 to 250. However, due to the high noise figure of SOA, the optical signal-to-noise ratios (OSNR) is less than 8.85 dB.

Multiwavelength passively mode-locked fiber laser with ultra-broad bandwidth

We demonstrate a stable multiwavelength passively mode-locked erbium-doped fiber laser with ultra-narrow wavelength spacing and ultra-broad bandwidth. It is realized by exploiting an intracavity birefringence-induced comb filter and inhomogeneous loss mechanism based on nonlinear polarization rotation. Stable 808-line wavelength lasing with wavelength spacing of 0.07nm and 3-dB bandwidth of 55.75nm is achieved at room temperature. If 5-dB bandwidth of 86.15nm is considered, the number of the lasing lines reaches 1248. In addition, the lasing wavelength lines and spacing could be flexibly tuned by modifying polarization-dependent cavity loss via properly rotating the waveplates.

Multiwavelength Laser With Adjustable Ultranarrow Wavelength Spacing

This paper investigates the use of a dual wavelength laser source, a frequency shifter, an erbium-doped fiber amplifier, and an optical filter to compose a multiwavelength fiber laser (MWFL) with an ultranarrow wavelength spacing. The frequency shifter can be achieved by modulating an optical carrier and an electrical sinusoidal signal in an optical single-sideband modulation format. The detuning range of the frequency shifting can be controlled by the applied electrical sinusoidal signal, and an MWFL with ultranarrow wavelength spacing can be achieved. Experimental results prove that 144 stable optical carriers can be generated simultaneously with a 10-GHz wavelength spacing, > 15-dB optical signal-to-noise ratio, and < 0.83-dB maximum peak power variation, if a dual wavelength laser source is fed into the MWFL and the frequency of the electrical sinusoidal signal is set to 10 GHz. Results prove that the ability of the proposed scheme practically and efficiently assist the progress of optical systems.

A stable multiwavelength SOA-based fiber ring laser with ultra-narrow wavelength spacing

This investigation demonstrates a stable multiwavelength fiber ring laser with ultra-narrow wavelength spacing using a semiconductor optical amplifier (SOA). A delay interferometer and a mirror are used as a double-pass interferometer to improve the signal-to-noise ratio in this experiment. Up to 181 stable lasing wavelengths with a wavelength spacing of 10.7 GHz and a signal-to-noise ratio of over 24 dB are produced at room temperature.

Tunable multiwavelength generation based on Brillouin-erbium comb fiber laser assisted by multiple four-wave mixing processes

A tunable multiwavelength Brillouin-erbium comb fiber laser with ultra-narrow wavelength spacing and a large wavelength number, employing a 135-m highly nonlinear fiber, has been experimentally demonstrated. The simultaneous presence of Brillouin pump and Stokes lines within the ring cavity initiate higher-order Stokes and anti-Stokes lines via multiple four-wave mixing processes. The experiment demonstrates that this is an effective solution of increasing the number of lasing lines. Up to 150 lasing lines in single-longitudinal-mode operation with a rigid wavelength spacing of 0.075 nm have been achieved at 1480 nm pump powers of 165 mW and Brillouin pump power of 12.0 dBm. The multiwavelength source exhibits a good stability on both the operating wavelengths and the output powers, and a 6-nm tuning range from 1562 nm to 1568 nm is obtained.

Multi-wavelength fiber optical parametric oscillator with ultra-narrow wavelength spacing

We propose a novel multi-wavelength fiber optical parametric oscillator (MW-FOPO) based on a ring cavity. A highly nonlinear fiber and a Mach-Zehnder interferometer formed by two 3-dB optical couplers are used as the gain medium and the comb filter, respectively. Multi-wavelength lasing of the MW-FOPO with an ultra-narrow wavelength spacing of about 0.08 nm is achieved. The output spectrum of the MW-FOPO covers a wavelength regime from 1510 nm to 1615 nm (for lasing wavelengths with the power that exceeds -60 dBm). The stability of the MW-FOPO is discussed and experimentally demonstrated. A comparison of the output spectra between the MW-FOPO and the multi-wavelength Erbium-doped fiber laser is also presented.

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.

Dual-wavelength narrow-linewidth light source with ultranarrow wavelength spacing based on the pump-induced thermal effects in an Er-Yb-codoped distributed-Bragg-reflector fiber laser

A dual-wavelength narrow-linewidth laser system, with ultranarrow wavelength spacing, is proposed and demonstrated. The operation principle of the laser system is based on the pump-induced thermal effects of the Er-Yb-doped fiber distributed Bragg reflector (DBR) laser. We designed and constructed a common Er-Yb-doped DBR fiber laser with proper parameters. With the pump power of the DBR laser increasing, the Bragg wavelengths and the bandwidths of the two gratings will change unequally. When the laser is pumped with 45 mW, we obtain stable dual-wavelength lasing with a 3-dB bandwidth of 0.014 nm and a wavelength spacing of 0.055 nm.

The design and fabrication of multitransmission‐band optical FBG filter with ultranarrow wavelength spacing

AbstractOptical filters with ultranarrow wavelength spacing of 0.068, 0.052, and 0.032 nm, are designed and fabricated on uniform fiber Bragg grating (FBG). Moreover, triple‐, and quadruple‐transmission bands with wavelength spacing of 0.050, 0.046 nm, respectively, are achieved through introducing three and four phase shifts along the fiber Bragg grating. These filters can be applied in the ultranarrow wavelength spacing filtering, photonic generation of microwave signal, multiwavelength distributed feedback Bragg lasing, etc. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1122–1125, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22392

Stable triple-wavelength fiber ring laser with ultranarrow wavelength spacing using a triple-transmission-band fiber Bragg grating filter

A stable 50-pm-spaced triple-wavelength fiber ring laser with nearly equal output power at each lasing line is achieved experimentally by incorporating a triple-transmission-band fiber Bragg grating filter in the fiber ring cavity. Such a laser will be very useful in applications requiring closely spaced multiwavelength components.

Tunable and Switchable Fiber Ring Laser Among Four Wavelengths With Ultranarrow Wavelength Spacing Using a Quadruple-Transmission-Band Fiber Bragg Grating Filter

Four pi-phase shifts are introduced in a uniform fiber Bragg grating (FBG) structure to realize a quadruple-transmission-band filter with ultranarrow 40-pm wavelength spacing. Four separate single-wavelength lasings at 1552.60, 1552.63, 1552.67, and 1552.71 nm, and three pairs of dual-wavelength lasings among above four wavelengths, are achieved stably by incorporating the quadruple-transmission-band FBG filter in a fiber ring cavity with a tunable uniform FBG acting as coarse frequency selection. This new kind of laser will be very useful in applications requiring closely spaced and tunable single- or dual-wavelength components