Intra-Cavity Frequency-Doubled VECSEL System for Narrow Linewidth Rydberg EIT Spectroscopy

Abstract

Vertical external-cavity surface-emitting lasers (VECSELs) augmented by intracavity nonlinear optical frequency conversion have emerged as an attractive light source of ultraviolet to visible light for demanding scientific applications, relative to other laser technologies. They offer high power, low phase noise, wide frequency tunability, and excellent beam quality in a simple and inexpensive system architecture. Here, we characterize the frequency stability of an intra-cavity frequency-doubled VECSEL with 690 mW of output power at 475 nm using the delayed self-heterodyne technique and direct comparison with a commercial external-cavity diode laser (ECDL). We measure the fundamental's Lorentzian linewidth to be 2𝜋 × 5.3(2) kHz, and the total linewidth to be 2𝜋 × 23(2) kHz. In addition, we perform Rydberg-state spectroscopy via electromagnetically induced transparency (EIT), observing narrow 3.5 MHz full-width halfmaximum EIT. By doing so, we demonstrate that intra-cavity frequency-doubled VECSELs can perform precision spectroscopy at the MHz level, and are a promising tool for contemporary, and future, quantum technologies.

In-depth investigation of emission homogeneity of InGaAs multiple quantum wells using spatially resolved spectroscopy

“…To overcome this limitation the vertical-external-cavity surface-emitting-laser (VECSEL) gain chip, in which the upper DBR is substituted by an external coupler, was developed. The external cavity geometry is suitable for optical pumping, and grants access to the laser cavity for the insertion of intracavity elements such as saturable absorber for mode locking 1 , nonlinear crystals for frequency doubling 2 or multiple VECSEL chips increasing output power while keeping high beam quality [3][4][5] . Another more key feature of VECSEL is the output power scalability.…”