Analog link performance of mode-locked laser diodes in the 60 GHz range

Abstract

In this paper, we present an experimental link performance analysis of mode-locked laser based radio-over fiber systems operating in the millimeter-wave range around 60 GHz. Both directly and externally modulation links are evaluated in terms of maximum output power, link loss, system noise figure and achievable dynamic range. Key parameters for the design and system application of mode-locked laser diodes are identified.

Relative intensity noise in optical heterodyning applied to millimeter-wave systems

“…From Fig. 2 and computations, it can also be observed that the beat-note RIN mmw is higher than the initial RIN ini by a factor I 2 /I 1 = 6.7 dB because the optical power of DFB 2 is larger , the RIN of less powerful mode (RIN 1 ) in (5) is then increased by a factor I 2 /I 1 compared to RIN 1 in (4) as expected.…”

“…2. For verifying (4) and (5), the bias current of the first laser DFB 1 is set to 15 mA (P opt = -2.1 dBm) while the bias current of the second laser DFB 2 is 90 mA (P opt = +3.5 dBm), thus RIN 1 and RIN 2 levels are very different for the first and second laser respectively. The experimental and theoretical results of initial RIN ini and beat-note RIN mmw are given in Fig.…”

“…In another approach for optical heterodyning, Quantum Dashed Mode Locked Lasers (QD-MLL) is used to demonstrate MMW beatnote linewidth around 100 KHz. Heterodyning advantage is that mode beating avoids any external electrical oscillator [5].…”