A resonator fiber optic gyroscope (RFOG) (100, 300, 700, 900) comprising: a first detector and a second detector; and a ring resonator comprising: a coil having a first end and a second end; and a device in optical communication with the coil, the device comprising: a first optical component; and a second optical component, wherein the device is configured to receive light from a source and receive light from each end (81, 82) of the coil, wherein the first optical component includes a first coupling device configured to direct at least a portion of light received from the source to the first end of the coil so that light propagates through the coil in a first direction, wherein the second optical component includes a second coupling device configured to direct at least a portion of light received from the source to the second end of the coil so that light propagates through the coil in a second direction, characterized in that the first coupling device is configured to transmit at least a portion of light received from the first end of the coil to the second coupling device, transmit at least a portion of light received from the second coupling device to the first end of the coil, and reflect at least a portion of light received from the first end of the coil to the first detector, and in that the second coupling device is configured to transmit at least a portion of light received from the second end of the coil to the first coupling device, transmit at least a portion of light received from the first coupling device to the second end of the coil, and reflect at least a portion of light received from the second end of the coil to the second detector. a first detector and a second detector; and a ring resonator comprising: a coil having a first end and a second end; and a device in optical communication with the coil, the device comprising: a first optical component; and a second optical component, wherein the device is configured to receive light from a source and receive light from each end (81, 82) of the coil, wherein the first optical component includes a first coupling device configured to direct at least a portion of light received from the source to the first end of the coil so that light propagates through the coil in a first direction, wherein the second optical component includes a second coupling device configured to direct at least a portion of light received from the source to the second end of the coil so that light propagates through the coil in a second direction, a coil having a first end and a second end; and a device in optical communication with the coil, the device comprising: a first optical component; and a second optical component, a first optical component; and a second optical component, wherein the device is configured to receive light from a source and receive light from each end (81, 82) of the coil, wherein the first optical component includes a first coupling device configured to direct at least a portion of light received from the source to the first end of the coil so that light propagates through the coil in a first direction, wherein the second optical component includes a second coupling device configured to direct at least a portion of light received from the source to the second end of the coil so that light propagates through the coil in a second direction, characterized in that the first coupling device is configured to transmit at least a portion of light received from the first end of the coil to the second coupling device, transmit at least a portion of light received from the second coupling device to the first end of the coil, and reflect at least a portion of light received from the first end of the coil to the first detector, and in that the second coupling device is configured to transmit at least a portion of light received from the second end of the coil to the first coupling device, transmit at least a portion of light received from the first coupling device to the second end of the coil, and reflect at least a portion of light received from the second end of the coil to the second detector.