Abstract: In a general aspect, a vapor cell includes a body defined by a stack of layers bonded to each other. The stack of layers includes a first end layer disposed at a first end of the body and a second end layer disposed at a second, opposite end of the body. Intermediate layers extend between the first and second end layers and define an internal cavity extending through the body between the first end layer and the second end layer. The stack of layers also includes first and second sets of tabs. The first set of tabs extends outward from the intermediate layers on a first exterior side of the body, and the second set of tabs extends outward from the intermediate layers on a second exterior side of the body. The vapor cell also includes a vapor or a source of the vapor disposed in the internal cavity.

Abstract: In a general aspect, a vapor cell includes a body defined by a stack of layers bonded to each other. The stack of layers includes a first end layer disposed at a first end of the body and a second end layer disposed at a second, opposite end of the body. Intermediate layers extend between the first and second end layers and define an internal cavity extending through the body between the first end layer and the second end layer. The stack of layers also includes first and second sets of tabs. The first set of tabs extends outward from the intermediate layers on a first exterior side of the body, and the second set of tabs extends outward from the intermediate layers on a second exterior side of the body. The vapor cell also includes a vapor or a source of the vapor disposed in the internal cavity.

Abstract: In a general aspect, a vapor cell includes a body defined by a stack of layers bonded to each other. The stack of layers includes a first end layer disposed at a first end of the body and a second end layer disposed at a second, opposite end of the body. Intermediate layers extend between the first and second end layers and define an internal cavity extending through the body between the first end layer and the second end layer. Each intermediate layer includes a through-hole that defines a portion of the internal cavity through the intermediate layer. The vapor cell also includes a vapor or a source of the vapor disposed in the internal cavity.

Abstract: In a general aspect, a vapor cell includes a body defined by a stack of layers bonded to each other. The stack of layers defines an array of cavities that includes first and second subsets of cavities. The first subset of cavities extends through intermediate layers of the stack of layers and the second subset of cavities extends entirely through the stack of layers. The vapor cell includes a vapor or a source of the vapor disposed in each of the first subset of cavities. The stack of layers includes a first end layer disposed at a first end of the body and a second end layer disposed at a second, opposite end of the body. The intermediate layers are positioned between the first and second end layers.

Abstract: In a general aspect, a device is disclosed for providing a reference frequency of light. The device includes a housing having a first opening and a second opening. A first optical window covers the first opening and is coupled to the housing by a first ceramic bond that forms a hermetic seal around the first opening. A second optical window covers the second opening and is coupled to the housing by a second ceramic bond that forms a hermetic seal around the second opening. The device also includes an etalon disposed within an evacuated volume enclosed by at least the housing, the first optical window, and the second optical window. The device additionally includes one or more supports suspending the etalon in the evacuated volume. The one or more supports are formed of a material having a thermal conductivity no greater than 5 W/m·K at room temperature.

Abstract: In a general aspect, a wavelength of light is measured. In some aspects, a wavelength measurement system includes an interferometer, a camera system, a sensor and a control system. The interferometer includes two reflective surfaces and a transmission medium between the two reflective surfaces. The interferometer is configured to receive an optical signal from a laser and produce an interferogram in response. The camera system is configured to receive the interferogram from the interferometer and generate interferogram data in response. The interferogram data represents the interferogram received from the interferometer. The sensor is configured to sense an environmental parameter of the transmission medium and generate sensor data in response. The control system is configured to perform operations including, receiving the interferogram data from the camera system and the sensor data from the sensor; and computing a wavelength of the laser based on the interferogram data and the sensor data.

Abstract: In a general aspect, an imaging method is presented that includes receiving, at a vapor-cell sensor, input optical signals and electromagnetic radiation from at least a test device to generate an output optical signal. The output optical signal is processed at a single pixel camera to generate camera output data. An image of the electromagnetic radiation is constructed by operation of a computer system based on the camera output data. In some implementations, the single pixel camera includes a patterned light generator and a photodetector. In these implementations, the imaging method includes receiving, at the photodetector, patterned instances of the output optical signal generated by the patterned light generator. Each patterned instance represents a respective portion of the image of the electromagnetic radiation. Moreover, the intensity of each patterned instance may be measured, by operation of at least the photodetector, to generate the camera output data.