Sub-MHz spectral linewidth in 1.5μm separate-confinementheterostructure (SCH) quantum-well DFB LDs

Simulation of natural linewidth and line form for semiconductor lasers; Interpretation of experiments

“…These are presented in Fig.3. Comparison of the calculated natural linewidth (Fig.1, 2) with the experimental natural linewidth (see Fig.3 in [1] and Fig.2 in [2]) shows their good fit.…”

“…The main phenomenological parameters varied in our R2=0,01. We can present the results of the experimental natural linewidth simulation (see Fig.3 in [1] and Fig.2 in [2] respectively) in Fig.1, 2. The line forms versus frequency for some values (1/Pk) from Fig.1 are transformed into one amplitude.…”

“…HE PROBLEM of natural linewidth in semiconductor lasers is of fundamental importance both theoretically and practically (narrow linewidth lasers are in great demand in coherent optical communication systems [1]). Measurements of natural linewidth for high power lasers: GaInAs/GaInAsP (SCH), (QW), (DFB LDs) lasers [1], gain-guided V-groove laser and oxide stripe laser [2], DFB Lasers [3][4][5], VCSEL laser [6], microcavity laser [7] and Fabry-Perot lasers [8][9][10] have shown various functional deviations from Schawlow-Townes formula [11] for natural linewidth  for one mode   =S 0 ·(1/ P ), (1) where S 0 =const, P is output power.…”

“…Measurements of natural linewidth for high power lasers: GaInAs/GaInAsP (SCH), (QW), (DFB LDs) lasers [1], gain-guided V-groove laser and oxide stripe laser [2], DFB Lasers [3][4][5], VCSEL laser [6], microcavity laser [7] and Fabry-Perot lasers [8][9][10] have shown various functional deviations from Schawlow-Townes formula [11] for natural linewidth  for one mode   =S 0 ·(1/ P ), (1) where S 0 =const, P is output power. Additional account of amplitude perturbations in semiconductor lasers [12] yielded the same modified formula (1) in which S 0 was changed to account for amplitude fluctuations. Various mechanisms, explaining occurrence of the contribution independent of output power at linewidth have been offered in the papers [9,13,14].…”

“…Various mechanisms, explaining occurrence of the contribution independent of output power at linewidth have been offered in the papers [9,13,14]. But the mechanisms proposed cannot explain minimum of experimental function  =F(1/ P ) [1][2][3][4][5][6][7][8]. Thus, it is possible to ascertain that understanding and description of experiments correspond to a review conclusion [14]: "in the questions, concerning linewidth and mechanisms defining it, there are a lot of unclear".…”