Wavelength-selective Feedback Research Articles

Compact diode-pumped passively Q-switched tunable Er–Yb double-clad fiber laser

Efficient repetitive passive Q switching of a cladding-pumped Er-Yb fiber laser has been demonstrated by use of an external-cavity configuration containing a Co(2+): ZnS crystal as a saturable absorber. Energies of as much as 60muJ in pulses of durations as short as 3.5 ns (FWHM), corresponding to a peak power of >10kW, have been generated, and the maximum slope efficiency with respect to the absorbed pump power was 13%. Using a bulk diffraction grating in the Littrow configuration to provide wavelength-selective feedback, we tuned the passively Q -switched fiber laser over 31 nm from 1532 to 1563 nm. The prospects for further improvement in performance are discussed.

A compact tunable narrow-band LD based on emission through the substrate and an external abnormal-reflection mirror

Due to the high beam divergence of standard laser diodes (LDs), these are not suitable for wavelength-selective feedback without extra optical elements. This letter reports on first prototypes of compact tunable LDs with wavelength-selective feedback via a so-called abnormal reflecting mirror of a low divergent beam coming from a special LD, emitting through the substrate. With this setup, tunable narrow-band (<0.7 nm) lasing is observed showing good temperature stability. Tuning over a range of 5 nm at a maximum power of 0.2 W was demonstrated.

Self-seeding of Fabry-Perot laser diode for generating wavelength-tunable chirp-compensated single-mode pulses with high-sidemode suppression ratio

We report an effective technique for generating wavelength-tunable chirp-compensated single-mode pulses with a high sidemode suppression ratio (SMSR) based on self-seeding a Fabry-Perot laser diode. This technique relies on the use of a tunable linearly-chirped fiber Bragg grating to provide wavelength-selective feedback, output filtering, and chirp compensation. With this technique, we have generated chirp-compensated picosecond pulses with a SMSR higher than 40 dB over a tuning range of 11.5 nm.

Generation of amplitude-squeezed light from 1550 nm distributed feedback semiconductor laser under wavelength selective optical feedback conditions

Excess noise that degrades the squeezing of a 1550 nm distributed feedback semiconductor laser is identified using a Mach Zehnder interferometer. This excess noise is reduced using wavelength selective optical feedback. Amplitude-squeezed states then are generated at room temperature.

Erbium-doped fiber amplifiers with wavelength-selective optical feedback

An optically-controlled fiber ring laser behaving as a low-speed all-optical inverter was demonstrated. Applications in fault location for lightwave systems, nonlinear optical circuitry and simple logic functions are described. Two inverters using erbium-doped fiber amplifiers were cross-coupled to form an all-optical guided-wave set/reset hip-hop that had greater than 40-dB extinction ratio and a state transition time of 1.6 ms.

Integrated mode-locked laser design with a distributed-Bragg reflector

The design of actively mode locked semiconductor lasers integrated onto a single substrate is studied using a new variation on the transmission-line laser model. The laser includes a distributed Bragg reflector to provide wavelength selective feedback. The behaviour of the device under various drive conditions is investigated. Pulses below 3 ps can be achieved by careful design of the Bragg region.

ANOMALOUS BEHAVIOR OF THE COMPETITION BETWEEN THE LASERING TRANSITIONS OF THE ARGON ION LASER

A wavelength-selective feedback modulation scheme was devised to study the competitive behavior of the lasering transitions in the argon ion laser and to determine the coupling relationships, radiative as well as collisional, between the inverted states of the ion. By means of monitoring cross modulation on lasering lines, spontaneous transitions, and discharge current, the interdependence of the lasering transitions was determined. Whereas lasering transitions which share common energy levels, upper or lower, are expected to compete adversely with each other, it was found that under certain conditions the contrary takes place.