No abstract

No abstract

No abstract

The efficient operation of a TEA CO(2) laser wherein the parallel spark channel preioniser of the laser itself functioned as a switch is reported. Simultaneous closure of the parallel gaps without an external switch has been achieved by ballasting them with mutually coupled inductances. The repetitive operation capability of such a laser is also discussed.

No abstract

Single-mode and multimode self-pulsing instability leading to chaos is reported in the 12.8-/xm emission from a homogeneously broadened NH 3 laser, near resonantly pumped by C0 2 laser radiation. Occurrence of instabilities on two independent emitting transitions over a wide range of operating conditions, including those for optimum lasing, indicate that this behavior is general for near resonantly enhanced two-photon Raman systems of this type.PACS numbers: 42.55.HqHere we report the first experimental observation of instabilities leading to chaos in a single-mode homogeneously broadened Raman laser system. These effects have been obtained on two independent emitting transitions over a wide range of operating conditions, including those for optimum lasing, which suggests that this behavior is indeed general for this broad class of near resonantly enhanced two-photon lasers. The route to chaos in this system is characterized by period doubling. Large variations in the basic pulsation period are found with changes in cavity fine tuning and the amplitude of these pulsations is itself modulated in some cases.The laser, which uses ammonia gas as the active medium, selected on the basis of well documented discrete spectroscopic features, efficient lasing action, and previous demonstration of passive instabilities, 1 is optically pumped by pulsed C0 2 laser radiation. The pump pulse is steady for more than sixty pulsation FIG. 1. Spatial intensity distribution of NH 3 emission taken with a pyroelectric array detector. A theoretical Gaussian profile is shown for comparison. periods of the instability, which thus establishes the steady-state nature of these effects. We concentrate on the aP($,0) lasing transition at 812 cm -1 optically pumped on the aR (6,0) transition 1.3 GHz below line center by the 9i?(16) C0 2 lasing emission at 1076 cm" 1 . This laser transition has been clearly identified as Raman in origin 2 for NH 3 pressures -1 -20 torr and pump intensity of ~ 0.6 MW/cm 2 . The pressure-broadened bandwidths of the pump and lasing transitions are 17.76 and 17.049 MHz/torr, respectively, 3 which, for our typical operating pressure of -8 torr, considerably exceed the Doppler bandwidth (74 MHz), which nevertheless is essentially irrelevant because only one velocity group of the molecules is pumped.A transversely excited atmospheric CQ 2 laser was O 100 NH3 PRESSURE (TORR) FIG. 2. Lasing and gain bandwidth of NH 3 emission as a function of pressure: dashed line, experimental data for lasing bandwidth determined from the PZT tuning range over which lasing occurred; solid line, prediction for gain bandwidth based on a FWHM value of 17.049 MHz/torr (Ref. 3).

No abstract

No abstract