Engineering Quantum Light sources
Historically, the group has used in-situ semiconductor microcavities with quantum wells or quantum dots to investigate light-matter interactions in solid-state systems. These microcavities are an excellent choice: they have high finesse mirrors of distributive layers of GaAs (n=3.5) and AlAs (n=2.9), and low mode-volume, making cavity quantum electrodynamics (cavity QED) in the weak and strong couple regimes possible. In our QD system, the QD linewidth (measured in fractions of a GHz) is always smaller than the cavity-mode linewidth. This is the commonly explored bad-cavity limit. In post or disk microcavities, the quality factors are in the 104 - 105 and with the small mode volumes, cavity QED effects are strong. These effects are also prominent in photonics-crystal cavities, as well (see our collaborator Edo Waks' efforts) where the quality factors are typically lower but the mode volume is much smaller. Since the QD emission wavelength varies dramatically from quantum dot to quantum dot, we need a way to tune the QD-microcavity system. Originally, temperature tuning is used, but other techniques are better. We investigate stain-tuning the quantum dot emssion, using the AC Stark effect, and direct cavity tuning using a fiber-based top mirror which can collect light and directly into the optical fiber.