Mode Stability Of Laser Research Articles

III-V/Si Hybrid Laser Stabilization Using Micro-Ring Feedback Control

We present a real-time approach for stabilizing a III-V/Si hybrid external-cavity laser implemented using microring monitoring and a feedback control loop. Laser mode stabilization over bias current and stage temperature variations are experimentally demonstrated. We achieved single-mode and mode-hop-free laser operation as the bias current was swept across 320 mA. The same feedback control also enabled wavelength-locked laser operation using an intracavity phase control. The feedback control was also applied to an integrated on-chip hybrid laser, and mode-hop-free laser operation was demonstrated over 23 °C substrate temperature variation.

In-band-pumped Ho:KLu(WO4)2 microchip laser with 84% slope efficiency.

We report on a continuous-wave Ho:KLu(WO4)2 (KLuW) microchip laser with a record slope efficiency of 84%, the highest value among the holmium inband-pumped lasers, delivering 201 mW output power at 2105 nm. The Ho laser operating at room temperature on the (5)I8→(5)I7 transition is in-band-pumped by a diode-pumped Tm:KLuW microchip laser at 1946 nm. Ho:KLuW laser operation at 2061 and 2079 nm is also demonstrated with a maximum slope efficiency of 79%. The microchip laser generates an almost diffraction-limited output beam with a Gaussian profile and a M2<1.1. The laser performance of the Ng-cut Ho:KLuW crystal is very similar for pump light polarizations ‖Nm and Np. The positive thermal lens plays a key role in the laser mode stabilization and proper mode-matching. The latter, together with the low quantum defect under in-band-pumping (∼0.08), is responsible for the extraordinary high slope efficiency.

Dynamic response of QWS-DFB lasers with convex tapered grating structure and non-zero facet reflection

Using finite difference time domain (FDTD) method, we analyze static and dynamic response of non-uniform grating quarter-wavelength shift distributed feedback QWS-DFB laser with non-zero facet reflection coefficients, both for large signal transient and small signal modulation. By introducing a convex tapered grating structure for QWS-DFB laser (XTG-DFB), it is shown that single mode stability of laser enhances and laser is less sensitive to random phase of reflection coefficients. We also show that XTG-DFB laser has better small signal response in comparison with uniform grating QWS-DFB laser.

Improving the stability of longitudinal and transverse laser modes

We show that laser mode stability can be improved with an intracavity mode selecting phase element. Without the phase element, a sub-wavelength change of the distance between the mirrors of a CO 2 laser leads to a substantial change of the transverse mode distribution, whereas with it the distribution remains essentially the same.

Mode stability of lasers and periodic optical systems

The concept of mode stability is considered in detail and a procedure is developed for determining the stability of laser resonators and optical waveguides containing arbitrary lens elements. It is found that under some conditions the addition of a laser medium with a gain profile makes oscillation or propagation impossible in an otherwise stable system. A new formalism is described for the propagation of off-axis modes.