186 K operation of terahertz quantum-cascade lasers based on a diagonal design

Abstract

Resonant-phonon terahertz quantum-cascade lasers operating up to a heat-sink temperature of 186 K are demonstrated. This record temperature performance is achieved based on a diagonal design, with the objective to increase the upper-state lifetime and therefore the gain at elevated temperatures. The increased diagonality also lowers the operating current densities by limiting the flow of parasitic leakage current. Quantitatively, the diagonality is characterized by a radiative oscillator strength that is smaller by a factor of two from the least of any previously published designs. At the lasing frequency of 3.9 THz, 63 mW of peak optical power was measured at 5 K, and approximately 5 mW could still be detected at 180 K.

Simulating terahertz quantum cascade lasers: Trends from samples from different labs

“…This fact and the simple layer sequence strategy make it a very interesting type of design when we want to compare samples of different origin. The lasers studied here are FathololoumiOE2012, 37 sample V812 of FathololoumiJAP2013, 38 KumarAPL2009A, 39 DeutschAPL2013, 40 and SalihJAP2013. 41 The designs are similar in principle, with small changes in doping densities and oscillator strengths.…”

Intersubband gain without global inversion through dilute nitride band engineering

“…1 Midinfrared ͑MIR͒ QCLs already deliver high power at room temperature 2 but at present the maximum operating temperature of a tetrahertz device is 186 K emitting at 3.9 THz. 3 Conventional designs emitting at a given frequency ប seem to have a maximum operating temperature T max Ϸ ប / k B . 4 The main difficulty at high temperatures is achieving population inversion and ISB lasing without inversion ͑LWI͒, [5][6][7] may be a solution for this microscopic bottleneck.…”

Terahertz quantum cascade lasers based on type II InGaAs/GaAsSb/InP

“…A revised design with lower anticrossing of these two states should decrease this current channel and hence decrease the threshold. 7 In conclusion, we realized the first terahertz quantum cascade lasers in the In 0.53 Ga 0.47 As/ GaAs 0.51 Sb 0.49 type II material system emitting around 3.9 THz. A reasonable device performance up to a heat-sink temperature of 102 K and a peak optical power as high as 1.8 mW proves that this InP-based heterostructure with its low effective masses and moderate conduction band offset also has a lot of potential in the terahertz range.…”