Active harmonic modelocking of an erbium fiber laser with intracavity Fabry-Perot filters

We present both experimental and theoretical investigations of the operation of a harmonically modelocked erbium fiber ring laser stabilized by an intracavity bit-rate etalon. Our model analyzes the effects of cavity components and operating parameters on laser stability and output pulse characteristics. The model predicts the output pulsewidth variation with laser cavity parameters such as cavity length, dispersion, and finesse of intracavity Fabry-Perot etalons. If the laser cavity length is not optimized, a maximum 50% increase in pulsewidth can occur at 5 Gb/s pulse rate. A repetition rate etalon with a finesse of 50 is sufficient to provide a side-mode suppression ratio of over 50 dB in the laser output. We also discuss how detuning from the optimal modulation frequency increases the excess noise that affects the laser stability. The theory predicts a maximum detuning range of /spl plusmn/100 kHz, which agrees with the experimental observations. These theoretical results can guide the design of similar lasers over a wide range of operating parameters.

[1]  Hermann A. Haus,et al.  Soliton versus nonsoliton operation of fiber ring lasers , 1994 .

[2]  David J. Richardson,et al.  320 fs soliton generation with passively mode-locked erbium fibre laser , 1991 .

[3]  D. M. Spirit,et al.  Novel method to suppress noise in harmonically modelocked erbium fibre lasers , 1993 .

[4]  P. Ho.  Phase and amplitude fluctuations in a mode-locked laser , 1985 .

[5]  W. Sibbett,et al.  Controlled amplifier modelocked Er/sup 3+/ fibre ring laser , 1990 .

[6]  A. Yariv.  Introduction to optical electronics , 1971 .

[7]  I. Duling.  Subpicosecond all-fibre erbium laser , 1991 .

[8]  Masatoshi Saruwatari,et al.  20 GHz transform-limited optical pulse generation and bit-error-free operation using a tunable, actively modelocked Er-doped fibre ring laser , 1993 .

[9]  A. Siegman,et al.  FM and AM mode locking of the homogeneous laser - Part I: Theory , 1970 .

[10]  Masatoshi Saruwatari,et al.  Generation of highly stable 20 GHz transform-limited optical pulses from actively mode-locked Er/sup 3+/-doped fibre lasers with an all-polarisation maintaining ring cavity , 1992 .

[11]  P.-T. Ho,et al.  The coherence time of a modelocked pulse train , 1984 .

[12]  D W Hall,et al.  Mode-locked erbium-doped fiber laser with soliton pulse shaping. , 1989, Optics letters.

[13]  H. Haus,et al.  A theory of forced mode locking , 1975, IEEE Journal of Quantum Electronics.

[14]  David J. Richardson,et al.  Passive harmonic modelocking of a fibre soliton ring laser , 1993 .

[15]  L. Mollenauer,et al.  Harmonically mode-locked fiber ring laser with an internal Fabry-Perot stabilizer for soliton transmission. , 1993, Optics letters.

[16]  K. Smith,et al.  All-optical clock recovery using a mode-locked laser , 1992 .

[17]  M. Adams,et al.  Optical waves in crystals , 1984, IEEE Journal of Quantum Electronics.

[18]  J. Goldhar,et al.  Performance characterization of a harmonically mode-locked erbium fiber ring laser , 1995, IEEE Photonics Technology Letters.