Low-threshold diode-laser-pumped OPOs based on QPM materials
Although attractive as compact sources of tunable infrared radiation, optical parametric oscillators pumped directly by single-mode diode lasers require extremely low thresholds. This talk will discuss the realisation of such low-threshold devices using QPM materials.
Extended mode-hop-free tuning by use of a dual-cavity, pump-enhanced optical parametric oscillator.
We report extended mode-hop-free tuning in a continuous-wave, pump-enhanced optical parametric oscillator (PE-OPO). We employ a dual-cavity configuration to allow independent control of the resonant pump and signal fields, and so we can suppress frequent mode hops in the signal as the pump is tuned in frequency. With the signal field clamped in frequency by an uncoated etalon, the idler field can be scanned smoothly through a range of 10.8 GHz. The PE-OPO outputs can also be tuned coarsely from 1.01 to 1.18 mum in the signal and from 2.71 to 3.26 mum and 4.07 to 5.26 mum in the idler. We find that increased idler absorption only slightly increases the oscillation threshold.
Hobbes and the Reception of Leviathan
Although there has been much discussion of the reception of Hobbes’s work, Hobbes’s response to his own reception has rarely received much consideration. This article looks at Hobbes’s engagements with his critics. Far from being rearguard actions by a philosopher under siege, or disingenuous attempts to curry favour with those in power, they can be read as moments when Hobbes in fact sought to convert what he saw as the “truth of speculation into the utility of practice.”