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A laser diode structure is designed and tested that permits the generation of high-power (∼100 W) picosecond-range optical pulses. Direct current pumping is used with a current pulse duration of a few nanoseconds and a current amplitude of ∼105 A/cm2. The main distinguishing feature of the structure is separation of the electron injector (p–n junction) from the active region by a potential barrier. The optical gain in the active region is controlled by the transverse electric field, which is determined by the magnitude of the current at each instant. The design allows emission wavelength control by means of band gap engineering.

A double heterostructure (DH) laser has been developed and tested with the aim of achieving high-power picosecond optical pulses in the near-infrared range for use in advanced laser radars and other applications. The physical idea consists of achieving fast gain control by means of temporal evolution of the electric field in the active region. The gain is controlled by the variation in current due to transformation in the built-in electric field across the active region, provided that a high current density is used for pumping. This transformation broadens the carrier energy distribution in the active region, thus suppressing lasing until the current pulse stops. The resulting carrier accumulation causes an enlargement in the power of the short-pulsing Q-switching mode. One of the most important features of the laser structure is the placement of the electron injector well outside the two hetero-barriers forming the active region. Three transient lasing modes were observed simultaneously in this laser diode, with a maximum difference in wavelength as large as 60 nm. One of them, a 45 W/ 25 ps Q-switching mode which appears near the trailing edge of the current pulse, being spectrally separated from the other two. A significant further increase in the power of the Q-switching mode can be expected from an optimized laser structure with two parasitic modes completely suppressed. The new laser structure produces much more powerful picosecond pulses than are obtainable from gain-switched lasers and allows lasing wavelength control by means of bandgap engineering.

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Light emitting module, which consist of superluminescent diodes (SLD) with spectral width 20 nm full width of half maximum (FWHM), simple optical objective and driver for constant output power has been designed. An influence of the length of coherence of the illumination source used on the correlation characteristics of spatial distributions of speckle intensity is investigated.