Timing jitter of Raman solitons.

We study the relative intensity noise (RIN) and timing jitter of a Raman soliton. We demonstrate that the RIN of an excitation pulse causes center-wavelength fluctuations of the resulting Raman soliton which translates by fiber dispersion into relative timing jitter (RTJ) between the Raman soliton and the excitation pulse. The Raman soliton's absolute timing jitter is dominated by the excitation pulse's timing jitter at low frequency and by the RTJ at high frequency. The experimental study reveals that RTJ can be significantly reduced by reducing the accumulated fiber dispersion (e.g., using less dispersive fibers with shorter length) experienced by the Raman soliton.

Low-cost, single-mode diode-pumped Cr:Colquiriite lasers.

We present three Cr3+:Colquiriite lasers as low-cost alternatives to Ti:Sapphire laser technology. Single-mode laser diodes, which cost only $150 each, were used as pump sources. In cw operation, with approximately 520 mW of absorbed pump power, up to 257, 269 and 266 mW of output power and slope efficiencies of 53%, 62% and 54% were demonstrated for Cr:LiSAF, Cr:LiSGaF and Cr:LiCAF, respectively. Record cw tuning ranges from 782 to 1042 nm for Cr:LiSAF, 777 to 977 nm for Cr:LiSGaF, and 754 to 871 nm for Cr:LiCAF were demonstrated. In cw mode-locking experiments using semiconductor saturable absorber mirrors at 800 and 850 nm, Cr:Colquiriite lasers produced approximately 50-100 fs pulses with approximately 1-2.5 nJ pulse energies at approximately 100 MHz repetition rate. Electrical-to-optical conversion efficiencies of 8% in mode-locked operation and 12% in cw operation were achieved.

Multi-photon microscopy with a low-cost and highly efficient Cr:LiCAF laser.

Multi-photon microscopy (MPM) is a powerful tool for biomedical imaging, enabling molecular contrast and integrated structural and functional imaging on the cellular and subcellular level. However, the cost and complexity of femtosecond laser sources that are required in MPM are significant hurdles to widespread adoption of this important imaging modality. In this work, we describe femtosecond diode pumped Cr:LiCAF laser technology as a low cost alternative to femtosecond Ti:Sapphire lasers for MPM. Using single mode pump diodes which cost only $150 each, a diode pumped Cr:LiCAF laser generates approximately 70-fs duration, 1.8-nJ pulses at approximately 800 nm wavelengths, with a repetition rate of 100 MHz and average output power of 180 mW. Representative examples of MPM imaging in neuroscience, immunology, endocrinology and cancer research using Cr:LiCAF laser technology are presented. These studies demonstrate the potential of this laser source for use in a broad range of MPM applications.

Effect of carrier lifetime on forward-biased silicon Mach-Zehnder modulators.

We present a systematic study of Mach-Zehnder silicon optical modulators based on carrier-injection. Detailed comparisons between modeling and measurement results are made with good agreement obtained for both DC and AC characteristics. A figure of merit, static VpiL, as low as 0.24Vmm is achieved. The effect of carrier lifetime variation with doping concentration is explored and found to be important for the modulator characteristics.

Low-threshold, room-temperature femtosecond Cr4+:forsterite laser.

We describe a low-threshold Cr(4+):forsterite laser which can be operated in continuous-wave as well as Kerr-lens mode-locked regimes at room temperature. To achieve low lasing thresholds, a 3-mm-long Cr(4+):forsterite crystal with a single-pass absorption of 41% was used to reduce the passive losses. Furthermore, a thin crystal was used to minimize the pump induced thermal gradients. During continuous-wave operation, absorbed threshold pump powers as low as 290 mW were obtained at 200C in single-pass pumping with a Yb fiber laser. To the best of our knowledge, this is the lowest pump threshold reported to date for Cr(4+):forsterite lasers. Furthermore, Kerr-lens mode locking could also be obtained using dispersion compensation with double-chirped mirrors. With an input pump power of 3 W, nearly transform-limited 89-fs pulses were obtained at a repetition rate of 200 MHz and with an average output power of 85 mW.