Yelong Hong

Demonstration of an excited-state Faraday anomalous dispersion optical filter at 1529 nm by use of an electrodeless discharge rubidium vapor lamp

An excited-state Faraday anomalous dispersion optical filter (ESFADOF) operating on the rubidium 5P3/2-4D5/2 transition (1529.4 nm in vacuum) is demonstrated, which utilizes an electrodeless discharge lamp rather than a laser-pumped Rb vapor cell as in a traditional ESFADOF system. When the lamp operates in the red mode with 3.5 W radio-frequency driving power, a twin-peak line-shaped transmission spectrum is obtained, which has a maximum transmittance of 21.9% (without taking into account the system loss and fluorescence background). ESFADOF by exploiting the 5P3/2-4D3/2 transition (1529.3 nm in vacuum) is also explored. A single-peak transmission spectrum with a maximum transmittance of about 3% is achieved. The electrodeless discharge lamp based ESFADOF holds promise for realizing a compact, low-cost, and good long-term frequency-stabilized laser system for optical communication applications.

Faraday anomalous dispersion optical filter with a single transmission peak using a buffer-gas-filled rubidium cell

A Faraday anomalous dispersion optical filter (FADOF) with a single transmission peak is achieved by using a buffer-gas (argon, 2 Torr)-filled rubidium cell. At room temperature, the transmission is 0.2% and the bandwidth of the transmission peak is 0.65 GHz. At a temperature of 63° C, the transmission rises to a maximum of 30.6%, with a bandwidth of 1.41 GHz. This FADOF may replace the use of interference filters or virtually imaged phased arrays in imaging modalities.

Diode laser operating on an atomic transition limited by an isotope ⁸⁷Rb Faraday filter at 780 nm.

We demonstrate an extended cavity Faraday laser system using an antireflection-coated laser diode as the gain medium and the isotope (87)Rb Faraday anomalous dispersion optical filter (FADOF) as the frequency selective device. Using this method, the laser wavelength works stably at the highest transmission peak of the isotope (87)Rb FADOF over the laser diode current from 55 to 140 mA and the temperature from 15°C to 35°C. Neither the current nor the temperature of the laser diode has significant influence on the output frequency. Compared with previous extended cavity laser systems operating at frequencies irrelevant to spectacular atomic transition lines, the laser system realized here provides a stable laser source with the frequency operating on atomic transitions for many practical applications.

Cesium active optical clock in four-level laser configuration

We propose an active optical clock scheme in four-level configuration with cesium atoms. The population inversion has been established experimentally between 7S1/2 state and 6P3/2 state in a thermal cesium cell with a 455.5 nm pumping laser. It can be used to generate active optical clock laser output in a bad cavity laser regime at the wavelength of 1469 nm.

Distribution of populations in excited states of electrodeless discharge lamp of Rb atoms

The intensity of fluorescence spectral lines of Rb atoms in the region of 350–1110 nm is measured in eletrodeless discharge lamp. The population ratio between the excited states is calculated according to the spontaneous transition probabilities with rate equations. At the same time, the population density of energy level is also obtained. The results provide the potential applications of electrodeless discharge lamp in atomic filter and optical frequency reference at higher excited states without a pumping laser.

Electrodeless-discharge-vapor-lamp-based optical atomic filter

An excited-state Faraday anomalous dispersion optical filter (FADOF) has been demonstrated, which utilizes a rubidium electrodeless-discharge-vapor-lamp rather than an external pump laser. When the lamp is turned off, the lamp-based filter can be treated as a ground-state FADOF. The compact lamp based FADOF holds promise for realing a frequency-fixed diode laser systems (such as a 1529 nm laser for optical communication application) and a multi-frequency filters.