Light emitted from single-mode semiconductor lasers generally has large divergence angles, and high numerical aperture lenses are required for beam collimation. Visible and near infrared lasers are collimated using aspheric glass or plastic lenses, yet collimation of mid-infrared quantum cascade lasers typically requires more costly aspheric lenses made of germanium, chalcogenide compounds, or ...

Narrow linewidth THz generation using a cascaded Brillouin fibre laser structure and a unitraveling carrier photodiode is proposed. Using two distributed feedback lasers separated by > 1 THz with 1 MHz initial linewidth, the linewidth of the realized THz source is found to be < 100 Hz at 1014.7 GHz without use of any active stabilization of the laser cavity or any microwave reference.

The wavelength tuning is an important issue for distributed feedback (DFB) lasers designs and applications. In this paper we have presented an algorithm to analyze the wavelength tuning characteristics of twosection index-coupled (TS-IC) DFB lasers in above threshold regime, by the means of the transfer matrix method (TMM), and the carrier rate equation. The versatility of the theoretical model...

A compact, narrow-linewidth, tunable source of THz radiation has been developed for spectroscopy and other high-resolution applications. Distributed-Bragg-reflector ~DBR! diode lasers at 850 nm are used to pump a low-temperature-grown GaAs photomixer. Resonant optical feedback is employed to stabilize the center frequencies and narrow the linewidths of the DBR lasers. The heterodyne linewidth f...

Monolithically integrated four-channel distributed feedback (DFB) laser array has been fabricated by metal organic vapor phase epitaxy (MOVPE) selective area growth for 1.55μm coarsewavelength division multiplexing (CWDM) systems. Wide-stripe MOVPE selective area growth and electron-beam lithography are used to obtain wide CWDM channel spacing of 20 nm. Optical outputs from the simultaneously b...

A tunable two-photon pumped solid-state laser based on polyfluorene is reported. A detailed investigation of the two-photon absorption in polyfluorene for both nanosecond and femtosecond time regimes in solution, and solid-state allows the determination of the most favorable conditions for lasing. Tunable distributed feedback lasers are made by spin coating from a polyfluorene solution on corru...

Mode-locking is a milestone in the history of lasers that allows the generation of short light pulses and stabilization of lasers. This phenomenon is known to occur only in standard ordered lasers for long time and until recently it is found that it also occurs in disordered random lasers formed by nanoscale particles. Here, we report the realization of a so-called quasi mode-locking of coheren...

In this paper we report, to the best of our knowledge, the first experimental realization of distributed feedback (DFB) semiconductor lasers based on reconstruction-equivalent-chirp (REC) technology. Lasers with different lasing wavelengths are achieved simultaneously on one chip, which shows a potential for the REC technology in combination with the photonic integrated circuits (PIC) technolog...