Resonantly pumped optical pumping injection cavity lasers

Abstract

An optical parametric oscillator is tuned to the resonance wavelength of the etalon in an optical pumping injection cavity (OPIC) laser with a type-II "W" active region, thereby minimizing the threshold pump intensity and maximizing the output slope efficiency. Previous OPIC experiments employed fixed-wavelength sources with only limited tuning available by adjusting the incident angle. Low threshold pump intensities of 330 W / cm 2 at 100 K and 14 kW/ cm 2 at 300 K (where the output wavelength is 3200 nm) were achieved. The energy conversion efficiency is found to decrease by over a factor of 100 when the pump wavelength is tuned from the resonance condition (1822 nm at 300 K) to only slightly off resonance (e.g., 1808 nm).

Transparency pump intensity and differential gain in resonantly pumped W optical pumping injection cavity lasers

“…31 ͑The absorbance correction is included in determining the external differential quantum efficiencies, d .͒ Parabolic fits to the thresholds yield the minimum values along with an independent determination of the resonant pump wavelengths. As in previous studies employing tuned OPO excitation, 17,31 to within experimental error the minimum I th and maximum d occur at the same R ͑which falls in between the integer nanometer OPO wavelength values employed to acquire the data͒.…”

“…The wafer from which the W-OPIC devices were cleaved was grown by molecular beam epitaxy on an n-GaSb substrate, as described previously. 17 The strain-compensated active region, which was designed for emission at Ϸ3 m at room temperature, has ten periods of an InAs/GaSb/InAs/ AlSb type-II W-well with thicknesses 21 Å/34 Å/21 Å/40 Å. These are surrounded on both sides by AlAs 0.08 Sb 0.92 holeblocking layers ͑100 Å͒ and GaSb spacer layers ͑5213 Å͒.…”

“…7,8,[10][11][12] While electrically injected lasers are the ultimate goal from the perspective of compact packaging and high wall-plug efficiency, their optically pumped counterparts have reached higher peak output powers 13,14 and maximum operating temperatures. [15][16][17] Dualwavelength emission optically pumped lasers have recently been demonstrated with considerable power at both wavelengths, [18][19][20] and high brightness operation of optically pumped type-II W semiconductor lasers 13,21 demonstrates strong potential for applications to long-range sensing, infrared countermeasures, and free-space optical communications in the mid-infrared.…”

“…While high output powers have been achieved using integrated absorbers, 13,14 OPIC lasers have attained higher maximum operating temperatures. 17,29,30 In the W-OPIC design, the W-well active region is centered between distributed Bragg reflectors ͑DBRs͒ that serve as mirrors for an etalon cavity whose resonance at the pump wavelength R results in multiple passes through the active region for greater absorption of the pump photons. GaSb spacers on each side of the active region can adjust the path length for a cavity of net optical thickness 2 R .…”

“…29 We also demonstrated previously that for diagnostic purposes, and also for cases where no standard pump source is available, an optical parametric oscillator ͑OPO͒ provides a convenient means for tuning the pump to any desired wavelength. 17,31 In the present work, an OPO is used to perform a cavity length ͑L c ͒ study on a series of W-OPIC lasers. This allows us to experimentally determine the temperature dependences of the transparency pump intensity and gain per unit pump intensity, and also to compare lasers with differing geometric factors.…”