Twin-stripe Lasers Research Articles

Transverse second-order mode oscillations in a twin-stripe laser with asymmetric injection currents

Transverse second-order mode oscillations in asymmetrically pumped twin-stripe lasers are described. Both far-field patterns and near-field patterns have two peaks, and a stronger peak appears on the weakly pumped side. The dependence of light intensity in one peak of the far-field pattern on the current into one stripe shows threshold characteristics. On application of rectangular pulse to one stripe, switching from one peak to the other occurs within 5 ns.

Optically steered twin-stripe laser beam scanner

Optically steered twin-stripe laser beam scanner

Room-temperature optically triggered bistability in twin-stripe lasers

Room-temperature optically triggered bistability in semiconductor lasers is reported for the first time. The optically bistable element consists of a twin-stripe laser. The bistable ‘switch-on’ and ‘switch-off’ are achieved by injecting light from two other twin-stripe lasers. By using twin-stripe lasers to provide the triggering pulses, no temperature control is required to match the lasing wavelengths. The optical bistability appears to be stable for at least as long as 300 ns, this time being the longest current bias pulse used by the authors.

New mechanism for bistable operation of closely coupled twin stripe lasers

Evidence for a novel mechanism causing bistable operation of closely coupled twin stripe lasers is reported. Current switched bistable operation has been demonstrated stably at room temperature, through the light beam being switched from a central mode to one where the optical filament crosses diagonally from under one laser stripe to the other.

Mode-guiding in bistable twin-stripe lasers

Mode-guiding mechanisms responsible for bistable properties of twin-stripe lasers are discussed with particular reference to optical injection effects. Calculations of the change in lasing field intensity as a function of both optical input power and injection current levels are presented.

Semiconductor laser bistable operation with an adjustable trigger

Hysteresis is demonstrated in the light output versus current characteristics of twin-stripe injection lasers subject to optical injection. The sensitivity of the device to optical injection is adjustable and allows an adjustable switch for bistable operation to be defined.

Optically induced spatial instability in twin-stripe-geometry lasers

The use of light injection to modify the lateral gain profile in twin-stripe injection lasers is described and consequent movement of the lasing optical field is demonstrated. A method of quantifying the sensitivity of the device to light injection is described and used to examine the dependence of optical instability upon injection current.

Diffusion and waveguiding effects in twin-stripe injection lasers

The properties of the twin-stripe injection laser are examined as functions of two parameters governing diffusion and waveguiding effects in the device. The carrier diffusion rate, as determined by the ambipolar diffusion coefficient,D, is shown to influence the current range over which lasing action is maintained. The curvature of the nonlinear portion of the light-current characteristic of the device is also changed asD is altered. It is found that the relative strengths of the guiding mechanisms acting upon the optical field further influence the characteristics of the structure.

Closely coupled twin-stripe lasers

The paper reports on novel effects exhibited by closely coupled twin-stripe lasers, Two forms of bistability have been observed. One effect is possibly caused by switching of waveguiding mechanisms from gain guiding to self-focusing. The second mechanism exhibits a large shift in near-field distribution from one side of the laser to the other. The speed of this bistable switching has been found to be between 800 and 900 ps. The effect of optical injection on bistability is also noted. Finally, twin-stripe lasers allow picosecond pulses as short as 20 ps to be generated, and the paper records the dependence of picosecond pulsewidth on asymmetric waveguiding.

Near-field control in multistripe geometry injection lasers

Control of the intensity and position of the near field is demonstrated in an analysis of twin-stripe and triple-stripe injection lasers. Calculations of file electrooptical properties of the structures are presented, taking into account the interaction between the carrier concentration profile and the optical field. For twin-stripe devices interstripe coupling is investigated as a function of stripe separation. For stripe separation comparable with stripewidth, the properties of triple-stripe lasers become of interest. Nonlinear light-current characteristics for the twin-stripe device are obtained and lead to an interpretation of such characteristics in conventional stripe geometry lasers.