Mechanism and characteristics of a fast-tuning Brillouin/erbium fiber laser

Abstract

A fast-tuning Brillouin/erbium fiber laser (BEFL) is investigated on its mechanism and characteristics in detail, in which a 4 m erbium-doped fiber (EDF) as both the Brillouin gain and linear gain media is coiled on a piezoelectric transducer (PZT) for laser frequency modulations. We demonstrate the fast-tuning mechanism theoretically and experimentally that only the lasing cavity mode is modulated, instead of the previous presumption that the Brillouin frequency shift of the EDF is modulated synchronously with the lasing mode. And the maximum tuning range (~60 MHz) is limited by the bandwidth of the Brillouin gain spectrum. The frequency tuning amplitude is direct proportional to the voltage on the PZT. The tuning rates reach up to 48 kHz. The BEFL keeps high-coherence property under fast frequency modulation. Its phase noise remains about -124 dB/Hz1/2 (normalized to 1 m optical path difference) at 1 kHz under 32 kHz modulations. This fast-tuning BEFL presents a wide range of applications in fiber sensors, optical fiber communications, and so forth.

Ultranarrow-Linewidth Brillouin/Erbium Fiber Laser Based on 45-cm Erbium-Doped Fiber

“…With the increase of the 980 nm pump power, the accurately Brillouin-frequency-downshifted BEFL is gradually excited. The wavelength difference between the BEFL and the BP is about 0.089 nm, corresponding to the Brillouin frequency shift of the EDF [18]. The longitudinal mode of the BEFL was measured by a scanning Fabry-Pérot interferometer ($1.5 GHz free spectrum range), as shown in Fig.…”

Linewidth Measurement of a Narrow-Linewidth Laser: Principles, Methods, and Systems

“…The structure of gain compensation loop delay self-heterodyne measurement technology is shown in Figure 1 e, which constructs the delay and frequency shift optical path in the MZI delayed self-heterodyne system into a fiber ring structure. The fiber optic ring mainly consists of couplers, AOMs, erbium-doped optical fiber amplifiers (EDFAs), and delay fibers [ 43 , 44 ]. The beam circulates in the fiber-optic ring according to a certain splitting ratio and undergoes an AOM frequency shift once per cycle.…”

High-efficiency Stimulated Brillouin Effect in Short-length Fibers Assisted by Twisted-mode Linear-cavity Erbium Doped Fiber Lasers

“…Although optical fibers are quite suitable to generate nonlinear effects due to their high-power density and long interaction length, many applications require shorter fiber lengths with the enhanced nonlinear efficiency. Recently, a mechanism that utilizes the gain in an intra-cavity erbiumdoped fiber amplifier (EDFA) to compensate for the cavity losses and enhance the SBS efficiency was proposed [4][5][6][7][8]. It was quite interesting that a compact Brillouin erbium-doped fiber ring laser (BEFRL) successively generated stokes light with only 45-cm of erbium-doped fiber (EDF) indicating an ultra-high efficient SBS process inside the short laser cavity [4].…”