Abstract

Noise characterization on the erbium-doped soliton ring laser have been reported previously.^1,2 These reports verify the extremely quiet operation of the soliton laser, and show that the timing jitter of the soliton laser is due to amplified spontaneous emission. The stretched-pulse erbium-doped fiber ring laser generates pulses whose energy is an order of magnitude larger than the soliton laser, and whose pulse width can be as short of 65 fs.³ Therefore, it is of interest to determine whether the noise performance of this laser is comparable to that of the fiber ring soliton laser. Though one preliminary attempt has been made,⁴ a systematic investigation of the noise characteristics of the stretched pulse laser does not exist. Figure 1 shows a schematic of the laser in its “reverse operation.” The ring consists of the erbium-doped amplifying fiber with positive dispersion, and a segment of passive fiber with negative dispersion. The waveplates are adjusted to provide the elliptic polarization necessary for the polarization-additive pulse mode-locking (P-APM). Output coupling is provided by three 3.3% output ports. The net dispersion of the laser is 0.009 ps². The cavity round trip time is 27.7 ns, and the average pulse power is 0.45 mW at port 2. By reversing the isolator and the order of the waveplates, one can operate the laser in its “forward” direction, an operation whose average pulse power at port 3 is 1.04 mW. The erbium fiber is pumped by a master-oscillator/power amplifier (MOPA) diode operating at 980 mn. This pump is essential to achieve low noise performance.

© 1996 Optical Society of America