Monolithic series-connected 1.55 µm segmented-ridgelasers

Scaling of the photon noise in semiconductor cascade lasers

“…Scaling method (a) is used in bipolar tunnel diode cascade and unipolar quantum cascade lasers, and scaling method (b) is used in bipolar segmented waveguide cascade lasers [2][3][4][5]10]. In method (a), the total impedance of all the gain stages scales as N Z d , where Z d is the impedance of a single gain stage.…”

“…Since impedance is inversely proportional to area, the impedance of each gain We also make the reasonable assumption that the output power of a cascade laser increases linearly with the increase in the total volume of the laser cavity. This implies that both the output power and the cavity volume scale as N α , where α = 1 for bipolar tunnel diode cascade lasers and 0 for unipolar quantum cascade lasers and bipolar segmented waveguide cascade lasers [3][4][5][6]. Since the output power of an N -stage cascade laser is given by the expression [2-6, 10]…”

“…Figure 1 shows a bipolar segmented waveguide cascade laser [3] in which a conventional laser waveguide is segmented into smaller sections that are connected electrically in series. Figure 2 shows a bipolar tunnel diode cascade laser [4,5] in which multiple PN junctions are connected electrically in series through reversed biased tunnel diodes.…”