Diode laser power output

Figure 5 shows three data points for the linewidths measured for a single mode PhSi-xSe diode laser (indicated by circles) in addition to the linewidth of the laser illustrated in Figure it (indicated by a square). Figure 5 shows the linewidths plotted as a function of the inverse of the single-ended laser power output. A linear extrapolation of the three data points of the single mode laser to zero inverse power indicated negligible linewidth intercept. Hence, the power-independent... 

The modest electrical drive requbements of these diodes, and the resulting option to power the laser with standard penlight (AA) batteries, allow these CnLiSAF lasers to boast an impressive electrical-to-optical efficiency of over 4 %, which until recently" was the highest reported overall system efficiency of any femtosecond laser source. The amplitude stability of the laser output was observed to be very stable with a measured fluctuation of less than 1% for periods in excess of 1 h. These measurements were made on a laser that was not enclosed and located in a lab that was not temperature-controlled. In a more enclosed and conbolled local envbonment we would expect the amplitude fluctuations of this laser to be extremely small. While the output powers achievable from these lasers have been limited by the available power from the AlGalnP red laser pump diodes, there are already sbong indications that commercial access to higher-power suitable diode lasers is imminent. 

Time-resolved spectroscopy is performed using a pump-probe method in which a short-pulsed laser is used to initiate a T-jump and a mid-IR probe laser is used to monitor the transient IR absorbance in the sample. A schematic of the entire instrument is shown in Fig. 17.4. For clarity, only key components are shown. In the description that follows, only those components will be described. A continuous-wave (CW) lead-salt (PbSe) diode laser (output power <1 mW) tuned to a specific vibrational mode of the RNA molecule probes the transient absorbance of the sample. The linewidth of the probe laser is quite narrow (<0.5 cm-1) and sets the spectral resolution of the time-resolved experiments. The divergent output of the diode laser is collected and collimated by a gold coated off-axis... 

Although solid state-lasers provide a considerably higher output power and can therefore be used similar to the functionality of EBWs and EFIs, the configuration is relatively large compared to diode lasers. Standard diode lasers are only several millimeters in size and can be produced with relatively low cost making them suitable for applications. 

Although the first laser demonstrated was a solid state ruby laser, for many years the most common commercial systems were gas lasers such as helium neon lasers and argon ion lasers, or lasers based on organic dyes. Helium neon lasers were frequently limited in output power, argon ion lasers required expensive, sophisticated power supplies and cooling sources, and the dyes used in dye lasers were messy and often toxic. In the past decade, solid state lasers and diode lasers have become the dominant players in the commercial marketplace. 

Another common laser class is that of gas lasers, which includes helium neon (HeNe) lasers, carbon dioxide (CO2) lasers, nitrogen lasers, and so on. The helium neon laser, widely used until the advent of the diode laser, was one of the first types developed and commercialized. As described above, it is a discharge-pumped gas laser, which generally produces an output measuring a few mW in power. 

Figure 7.6. Output of an AIGaAs diode laser operating at the indicated optical output powers. For this device, low-power operation (C and D) results in multimode output covering about 2 nm of wavelength. At higher powers (A and B), a single mode operates with a linewidth of 0.2 nm. (Adapted from Reference 2, p. 338.)...

Figure 7.7. External cavity diode laser, such as the Spectra Diode Labs 8530. All components are contained in a 3 x 4 x 10 in. case, and the output power is 300 mW.

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