Semiconductor optical gain

About: Semiconductor optical gain is a research topic. Over the lifetime, 5997 publications have been published within this topic receiving 96505 citations.

Low-frequency fluctuation induced by injection-current modulation in semiconductor lasers with optical feedback.

Abstract: Low-frequency fluctuations in semiconductor lasers with optical feedback are investigated when high-frequency modulation is applied to an injection current. Synchronization of the laser output power with the modulation within +/-3 MHz centered at the frequency corresponding to the external cavity mode was observed. However, for modulation of the detuned frequency from the external cavity mode, low-frequency fluctuations were induced in the laser output power, and these fluctuations were observed within a range of modulation of approximately +/-100 MHz at the center frequency of the external cavity mode.

Dielectric grating induced by cavity standing wave as a new explanation of origin of nonlinear gain in semiconductor diode lasers

Abstract: The nonlinear gain due to induced index and gain grating caused by the cavity standing wave is analysed using coupled-mode equations. The grating coupling coefficient is calculated using the rate equation with an ambipolar diffusion term. The self-consistent solution of the coupling coefficient and the optical field indicate the existence of a nonlinear gain term with a surprisingly large magnitude. This gain nonlinearity is shown to contribute significantly to the modulation damping factor of semiconductor diode lasers.

Longitudinal spatial inhomogeneities in high-power semiconductor lasers

Abstract: We study the spatial distribution of the temperature, gain, and carrier density along the longitudinal direction of a semiconductor laser cavity. In high-power laser diodes, the use of asymmetrical facet reflectivities creates a spatially nonuniform photon intensity profile and results in inhomogeneous temperature and carrier distributions along the active stripe. These profiles are determined from direct measurements of blackbody radiation and the spontaneous emission from the laser cavity. The temperature of the active stripe is observed to be significantly higher than that of the heat sink during lasing, and the effect of temperature on the modal gain spectrum is analyzed. We demonstrate that the local carrier density and optical gain within a laser are not pinned beyond threshold. A spatially inhomogeneous gain profile is possible in laser cavities as long as the threshold condition that the averaged round-trip gain equals the total losses is maintained. A theoretical model is presented which explains the observed experimental data. >

Integrated semiconductor laser with electronic directivity and focusing control

Abstract: An integrated semiconductor laser device includes electronic direction and focusing control. The integrated semiconductor laser device may be used for either transmitting output laser beams or as a laser amplifier for receiving incoming laser beams. The direction and focusing control of the device operates by applying electric current to electrodes coupled to an active channel within an extension chamber of the integrated semiconductor laser device. The applied currents inject a minority carrier density distribution into the active channel. Since the speed of light within a semiconductor changes with minority carrier density distribution, a laser beam wave front may be shaped by the injected minority carrier density distribution to direct and/or focus a laser light beam. The direction and focusing control is completely integrated within the semiconductor laser device and time constants for the electronic direction and focusing control are in nanoseconds.

Nonplanar large optical cavity GaAs/GaAlAs semiconductor laser

Abstract: We report pulsed room‐temperature operation of a nonplanar large optical cavity semiconductor laser. As a result of a single LPE growth in an etched channeled substrate, a curved cavity is created which guides the laser light in both transverse dimensions. Representative lasers exhibit 50‐mA thresholds, 40% differential quantum efficiency, 25‐mW power output without kinks, and stable near‐ and far‐field optical patterns.