Intrinsic nonlinearity of the light–current characteristic of semiconductor lasers with a quantum-confined active region

Abstract

We describe a mechanism of nonlinearity of the light-current characteristic common to heterostructure lasers with a reduced-dimensionality active region. It arises from ͑i͒ noninstantaneous carrier capture into the active region and ͑ii͒ nonlinear ͑in the carrier density͒ recombination rate outside the active region. Because of ͑i͒, the carrier density outside the active region rises with injection current above threshold, and because of ͑ii͒, the useful fraction of current ͑that ends up as output light͒ decreases. We derive a universal closed-form expression for the internal differential quantum efficiency that holds true for quantum well, quantum wire, and quantum dot lasers.

Effect of excited states on the ground-state modulation bandwidth in quantum dot lasers

“…1). In this regard, the role of recombination via excited states in QDs is similar to that of parasitic recombination in the OCL 13 (Fig. 1).…”

Optical power of semiconductor lasers with a low-dimensional active region

“…The internal differential quantum efficiency would be given by Eq. (14) in which both hj capt;th i harmon and hj capt;th i geom would simply turn into the capture current density at the lasing threshold, which would be the same for electrons and holes. Hence, we see that, in the expression for g int in the "five rate equations model," the asymmetry between the electron and hole capture is effectively taken into account by the harmonic and geometric means of the current densities of electron and hole capture at the lasing threshold.…”

“…It is the capture velocity (measured in cm=s), which is a proper parameter describing the carrier capture into a QW. [6][7][8][9][10][11][14][15][16] The thermal escape time and the capture velocity are related to each other (see Ref. 16 for the general expression relating s n;p;esc and v n;p; capt;0 ).…”

“…1,2 Among them is the carrier capture from a bulk reservoir region [optical confinement layer (OCL)] into a low-dimensional active region. [3][4][5][6][7][8][9][10][11][12][13][14][15][16] Analytical models can provide insights into these processes and be used to optimize the laser structures to achieve desired operating characteristics. To develop analytical approaches, certain assumptions and simplifications should be made.…”

Direct and indirect capture of carriers into the lasing ground state and the light-current characteristic of quantum dot lasers

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In Refs. [19][20][21], the lightcurrent characteristic (LCC) of semiconductor lasers (the optical power as a function of the pump current) was calculated considering only direct capture of carriers from the optical confinement layer (OCL) into the lasing state in a quantum-confined active region. In Ref.…”