Biomedical subjects

M E Fermann

Publications and source records attributed to M E Fermann.

4 recordsLinked to original sources

PubMed2006

Fiber-laser frequency combs with subhertz relative linewidths.

We investigate the comb linewidths of self-referenced, fiber-laser-based frequency combs by measuring the heterodyne beat signal between two independent frequency combs that are phase locked to a common cw optical reference. We demonstrate that the optical comb lines can exhibit instrument-limited, subhertz relative linewidths across the comb spectra from 1200 to 1720 nm with a residual integrated optical phase jitter of approximately 1 rad in a 60 mHz to 500 kHz bandwidth. The projected relative pulse timing jitter is approximately 1 fs. This performance approaches that of Ti:sapphire frequency combs.

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PubMed2004

Frequency metrology with a turnkey all-fiber system.

The repetition rate and carrier-envelope phase offset frequencies of a turnkey, all-fiber-based continuum generator were phase locked to a hydrogen maser. The frequency of the hydrogen maser was calibrated with a highly stable cesium atomic clock, and therefore a fully phase-locked optical frequency comb with well-defined absolute frequencies was obtained. In contrast with the commonly used Ti:sapphire-laser-based systems, we have accomplished a fully turnkey system with no user-adjustable parts. To evaluate the performance of this novel system, we performed absolute frequency measurements in the telecommunications region and at 1064 nm and compared them with our traditional Ti:sapphire-based comb.

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PubMed2004

Chirped pulse amplification with a nonlinearly chirped fiber Bragg grating matched to the Treacy compressor.

We demonstrate a fiber chirped pulse amplification system that uses an engineered nonlinearly chirped fiber Bragg grating stretcher dispersion matched to the Treacy compressor. The seed pulses at 1558 nm are stretched to 720 ps, amplified by more than 50 dB to 6.5-microJ energy, and recompressed to 940 fs. After almost 1000 times compression the pulses are within 30% of the bandwidth limit and have a contrast ratio of better than 30 dB.

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PubMed2000

Self-similar propagation and amplification of parabolic pulses in optical fibers.

Ultrashort pulse propagation in high gain optical fiber amplifiers with normal dispersion is studied by self-similarity analysis of the nonlinear Schrödinger equation with gain. An exact asymptotic solution is found, corresponding to a linearly chirped parabolic pulse which propagates self-similarly subject to simple scaling rules. The solution has been confirmed by numerical simulations and experiments studying propagation in a Yb-doped fiber amplifier. Additional experiments show that the pulses remain parabolic after propagation through standard single mode fiber with normal dispersion.

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