A novel distortion reduction scheme for multiple quantum well gain lever laser diodes

Abstract

We propose a novel linearization scheme utilizing a feedback harmonic injection technique for multiple quantum well gain lever laser diodes. Gain lever and distortion characteristics are analyzed for a laser diode with a section length ratio of 97:03 at 2.4 GHz. Feedback signals are derived from the longer section of the laser diode, which is the unique feature of this scheme, when compared with the conventional feedback linearization schemes. The amplitude and phase of the feedback harmonic signal are precisely adjusted to get minimum intermodulation distortion. A gain lever of 7.3 and 14 dB reduction in third-order intermodulation distortion are obtained using our new technique.

Performance analysis of a digital fiber optic link incorporating gain‐levered laser diode transmitter

“…Two‐section laser diode also exhibits optical bistability apart from gain‐levered effect, which is reported earlier . Gain‐levered effect is generally investigated in two‐section laser diode to improve the amplitude modulation efficiency . Modulation depth improvement by gain‐levered mechanism is demonstrated and theoretically explained by Vahala et al It is well known that signal to noise ratio of any communication link depends on modulation depth .…”

“…Most of the reports in gain‐levered laser diode that are published earlier addressed the modulation and distortion characteristics of the device for analog optical fiber link applications . Analysis of intermodulation distortion and reduction of third‐ and fifth‐order intermodulation components in two‐section gain‐levered laser diode were reported . Gain‐levered laser diode also finds application in tunable wavelength devices .…”

Analysis of the effect of optical confinement factor on the distortion performance of gain lever laser diode

“…The photon density (S) in the laser diode is assumed to be uniform along the cavity. The rate equations for longer and shorter section carrier densities and photon density are given as [3][4][5][6]14], …”

“…Improvement in optical modulation depth is also observed in such devices due to gain lever effect [7][8][9][10][11][12][13][14][15]. The inherent nonlinearity of the two section gain lever laser diode also produces harmonic and intermodulation distortion.…”

“…Earlier, we proposed a novel distortion reduction scheme in gain lever laser diode based on feedback harmonic injection technique. RF signals are extracted from longer section of the laser diode and used for IMD3 reduction [14]. The third and fifth order intermodulation components are simultaneously reduced by our proposed technique [15].…”