Terahertz-rate optical pulse generation from a passively mode-locked semiconductor laser diode

Abstract

We report what is to our knowledge the first demonstration of terahertz-rate optical pulse generation by harmonic passive mode locking in a distributed-Bragg-reflector laser diode. Along with the fundamental repetition rate of 38.8 GHz, we observed 400-GHz, 800-GHz, and 1.54-THz harmonics, depending on the bias condition of gain section. The pulse envelope for 1.54-THz pulses was in good agreement with a calculation from the Fourier transformation of the optical spectrum, indicating that the output pulses are transform limited.

<title>Stabilization of ultrafast mode-locked diode lasers and its application for narrow-linewidth millimeter wave sources</title>

“…Furthermore, in practice it is difficult to precisely control the length of a LD when the cavity length becomes shorter than 100 im (corresponding to approximately 400 GHz repetition). The composite cavity configuration is also useful for realizing subterahertzterahertz optical pulse trains: for example, an MLLD with an integrated distributed feedback reflector (DBR) generated a terahertz rate optical pulse train due to an unintentional sub-cavity effect of the DBR [8].…”

Multi-Harmonic Optical Comb Generation

“…For example, mode-locking, of semiconductor [2] or Er:Yb: glass lasers [3] can provide a good optical signal-to-noise ratio (OSNR), however, they require equalizing filters to enable reasonable flatness, and the line spacing of the produced comb is fixed by the cavity length. Techniques based on highly nonlinear fibers by using four-wave mixing effects [4] may enable combs of wide optical bandwidth, but they are bulky and require optical power pumps.…”

Self-oscillating millimeter-wave generation using reciprocating optical modulator

“…Self-oscillation is an important factor to achieve low-cost ROF signal generation. It is known that passively mode-locking techniques can generate harmonic modulated components with self-oscillation [3] but the control of starting and maintaining the mode-locking is not a little complex.…”