Low noise single frequency linear fibre laser

A Review of Recent Developments in Fiber Optic Sensor Technology

“…This area is attracting interest both from the communications research community, for tunable single frequency devices for wavelength division multiplexed networks [139,140], and in the sensing field for strain, temperature, and very high resolution The basic form of a fiber Bragg grating laser utilizes two gratings of matched Bragg wavelength to create an in-fiber cavity. The use of a doped fiber section between the gratings (e.g., erbium) allows the system to be optically pumped to provide cavity gain and thus lasing.…”

“…Multimode A REVIEW OF RECENT DEVELOPMENTS IN FIBER OPTIC SENSOR TECHNOLOGY 313 operation of the cavity will occur if the cavity mode spacing ( ν = c/2nL, where L is the cavity length, n is the fiber index, and c is the free-space velocity of light) is significantly less than the bandwidth of the gratings. For single mode operation with typical FBG bandwidths of ∼0.1 to 0.2 nm, the cavity is required to be on the order of a few cm (2 or 5 cm) [139]. This can necessitate the use of very highly doped fiber and high pump powers to achieve sufficient gain in the cavity to support lasing.…”

Frequency and Intensity Noise of Single Frequency Fiber Bragg Grating Lasers

“…RIN reduction for a single frequency Er-doped fiber Bragg grating laser by applying negative feedback from a monitor detector to the pump current has been demonstrated in [36,37]. Promising results have also been achieved for 980-nm pumped Er:Yb glass lasers by applying very high speed electronics to compensate for the slow energy transfer from Yb to Er in these lasers [38].…”

“…Promising results have also been achieved for 980-nm pumped Er:Yb glass lasers by applying very high speed electronics to compensate for the slow energy transfer from Yb to Er in these lasers [38]. In order to investigate what happens to the laser frequency noise when intensity stabilizing feedback is applied, we implemented a PID controller of the same type as used in [36] (a proportional gain stage, an integrator, and a differentiator connected in parallel) in a feedback path from the detector monitoring RI to the pump drive current. Figure 9 shows the measured RIN and frequency noise ν rms from a 50-mm long Ionas fiber DFB laser (not identical, but similar to the one investigated in the previous sections) which was pumped by ∼110 mW of 1480-nm power.…”

Optoelectronics in Suppression Noise of Light

“…High frequency beating noise from fiber ring laser can be reduced by intracavity spectral filtering (Sanders, S. et al1992). Intensity noise of fiber laser at the relaxation oscillation frequency was suppressed by integrating a negative feedback circuit (Spiegelberg, C. et al 2004;Ball, G. et al 2008). Optoelectronic feed forward, which is easy and practical, is a method to suppression noise of light easily.…”