Quantum-limited noise performance of a mode-locked laser diode

Abstract

Low-noise operation of a 9-GHz hybridly mode-locked laser diode is demonstrated. The integrated timing jitter was 47 fs (10 Hz to 10 MHz) and 86 fs (10 Hz to 4.5 GHz), with a pulse width of 6.7 ps. The noise performance as a function of filter bandwidth and oscillator noise is also addressed.

Low-Jitter and High-Power 40-GHz All-Active Mode-Locked Lasers

“…Ideally, one should evaluate the phase noise all the way to the Nyquist frequency, but for the present measurement, we are limited in dynamic range. While it is possible to trade low-frequency jitter for high-frequency jitter and amplitude noise using harmonic mode-locking [6], the present lasers are fundamentally mode-locked and we, therefore, expect the noise to fall off at large offsets [7]. The operating conditions for the lasers are given in the legend of the lower graph in Fig.…”

“…The pulsewidth for this measurement was 2.5 ps but the time-bandwidth product was 0.6 and a large amount of excess spectral components on the short wavelength side was present in the optical spectrum. Intracavity spectral filtering can be used to further lower the jitter [3], [7] and decrease the time-bandwidth product toward the transform limit, and improved jitter measurement methods are also expected to lower the measured values [6], [7].…”

Analysis of Timing Jitter in External-Cavity Mode-Locked Semiconductor Lasers

“…The two counter-propagating waves evolve according to the traveling-wave equations (3) being the modal group velocity (GV), the modal group-velocity dispersion (GVD), the internal losses, and the optical confinement factor of the buried waveguide. The SVE of the material polarization has the formal expression (4) being the material gain, the variation in propagation constant, the carrier-induced refractive index, and a variable describing their functional dependence on material variables like carrier density and temperature (see Section II.B). Since the electric fields are almost monochromatic around , we expand and in Taylor series around up to second order dispersion in both gain and carrier-induced refractive index.…”

“…In particular, the feasibility of these devices in high-speed communication systems, using optical time-division multiplexing (OTDM), relies on the possibility of achieving sufficiently short pulsewidths and low timing jitter (less than 10% the bit period [4]). For instance, transmission at 160 Gb/s (640 Gb/s) requires timing jitter less than 500 fs (100 fs).…”

Attosecond‐precision ultrafast photonics

“…Although state-of-the-art microwave sources with sub-10-fs timing jitter exist 1 , they are rack-sized, highcost instruments and impose a difficulty in scaling down for chip-scale signal processing applications. In recent years, there has been extensive research on various types of lownoise mode-locked lasers, including actively mode-locked semiconductor lasers [14,15], active harmonically modelocked fiber lasers [16], active harmonically mode-locked waveguide lasers [17], and passively mode-locked glass lasers [18,19]. As will be presented later, optical pulse trains generated from standard, passively mode-locked Erfiber lasers can easily achieve sub-10-fs and sub-fs timing jitter for offset frequencies above 10 kHz and 100 kHz, respectively [20].…”