ORS
Ultrastable Laser System

Specifications

Advanced Features and Benefits

Top-of-the-line system designed for ultimate performance
Ultimate phase noise and frequency stability
Easily transportable (mechanical transport lock)
Highly customizable—available over wide range of wavelengths and with many options
Robust and well-engineered single 19” rack system including monitor & control system and vibration isolation platform.
Automated laser locking—24/7 operation

	ORS
Wavelength	500–1600 nm (IBS coatings), 900–1600 nm (XTAL coatings)
Stability (MADEV at 1 s, linear drift removed)	<7 x 10^-16 (with FS-XTAL option) <1 x 10^-15 (with FS-IBS option) <2 x 10^-15 (with ULE-IBS, standard system)
Linewidth	<1 Hz
Phase Noise (laser source dependent)	ULE-IBS FS-XTAL at 10 Hz -7 dBc/Hz -13 dBc/Hz at 100 Hz -47 dBc/Hz -47 dBc/Hz at 1000 Hz -70 dBc/Hz -70 dBc/Hz For all Models Spurious Signals <-20 dBc
Output Power	>10 mW (FC/APC connector), high power on request
Cavity Spacer	12.1 cm, ULE, cylindric design
Free Spectral Range	1.24 GHz
Linear Drift Rate	approx. 150 mHz/s
Vibration Isolation Platform	included

Description

The Optical Reference System (ORS) is designed for uncompromised performance. It delivers ultra-narrow linewidth laser light with outstanding frequency stability.

The system’s centerpiece is a high-finesse Fabry-Pérot cavity (cylindric spacer with a length of 12.1 cm) serving as a reference for a CW laser. The cavity is made out of ultra-low expansion glass (ULE) and is operated in vacuum at the point of zero thermal expansion. The reference cavity is actively decoupled from vibrations and acoustically isolated allowing for ultimate performance also in rough laboratory environments. An easy-to-use cavity-locking mechanism ensures portability without realignment of the optical paths.

The system is operated by the newest generation of Menlo Systems’ proprietary SYNCRO controller—a modular electronics platform designed for versatility and intuitive use. It incorporates all required electronics, e.g., a low-noise laser driver and a very fast (analog) servo loop for laser frequency stabilization. The user controls all parameters using either the 7” front-panel touchscreen or a GUI on a remote PC. The onboard software ensures automatic cavity locking and system monitoring.

Watch a system demonstration of the ORS system here:

Options

Crystalline Mirror Coating Package

Product Code: ORS-FS-XTAL
For ultimate frequency stability, the ORS-FS-XTAL Option is indispensable. Here, highly reflective crystalline coatings (available above 900 nm) are used on fused silica substrates as cavity mirrors. This strongly reduces the thermal noise floor. In addition, the intracavity power is actively stabilized with feedback to an AOM.
Fused Silica Mirror Substrate Package

Product Code: ORS-FS-IBS
The Fused Silica Mirror Substrate Package is an economic solution to reduce the thermal noise floor. Here, fused silica mirror substrates are used instead of ULE substrates. In addition, the intracavity power is actively stabilized with feedback to an AOM.
AOM Frequency Shift Package

Product Code: ORS-AOM-FSH
The ORS can be tuned over tens of picometers in steps of the free spectral range. To reach a specific frequency in-between these discrete steps (e.g., the Strontium transition at 698 nm), an additional noise-free frequency shift is applied using acousto-optic modulator. The AOM Frequency Shift package provides the precise output at the desired frequency for the ORS.
EOM Sideband Lock Package

Product Code: ORS-EOM-SBL
The EOM Sideband Lock Package provides a broadly tunable, ultrastable laser output. Here, an electro-optical modulator (EOM) is used to generate sidebands on the laser light that is sent to the cavity. Subsequently, a modulation sideband is coupled into the reference cavity, while the carrier is used as a frequency tunable, ultrastable user output. A tuning of up to half of the free spectral range is possible.
Fiber Noise Cancellation Package

Product Code: ORS-FNC
For transmission of sub-Hz linewidth laser light for more than a few meters, we recommend active phase noise compensation of the ultrastable output. The ORS-FNC interferometrically detects the phase noise induced by temperature variations and vibrations in the fiber and actively compensates this using a phase-locked loop and an AOM as actuator. The residual noise contribution of such a stabilized fiber link is well below the frequency stability of the ORS.
Mirror Coatings for Multiple Wavelengths Package

Product Code: ORS-MWL
For simultaneous stabilization of multiple lasers to the same reference cavity, we provide customized cavity mirrors. These custom coatings are highly reflective in two or multiple wavelength ranges.
Second Harmonic Generation Package

Product Code: ORS-SHG
It can be advantageous to realize an ultrastable laser system at a longer wavelength and frequency double its output using the ORS-SHG package (e.g., at 1397 nm for the Strontium clock transition at 698 nm). Frequency doubling can be integrated into your system with free-space or fiber-coupled output.
High Output Power Package

Product Code: ORS-FA, ORS-TA
Higher output power levels can be reached using low noise fiber amplifiers (ORS-FA) or semiconductor optical amplifiers with a tapered geometry (ORS-TA). When amplifiers are being used, they are placed within the frequency stabilization servo loop and thus merely affect the system’s stability.
Cavity de-Drifting Package

Product Code: ORS-DDRIFT
The inevitable shrinking drift of the reference cavity can partially be pre-compensated using a software-based scheme in conjunction with an AOM. If the system is equipped with a package that includes an AOM (ORS-FNC, ORS-AOM-FSH or FS substrates) de-drifting can also be realized via this AOM.
Digital Servo Interface for Stabilization to External Atomic Transition Package

Product Code: ORS-DSRV
We provide a digital interface with which the frequency of the ultrastable output can be stabilized to an external clock transition. The user supplies a frequency error reading and the SYNCRO control platform integrates this and feeds back to an AOM in order to stabilize the laser to the external reference. If the system is equipped with a package that includes an AOM (ORS-FNC, ORS-AOM-FSH or FS substrates) stabilization to an external transition can also be realized via this AOM.
General information

Electronic modules that come with an extension package typically slide into Menlo Systems SYNCRO control platform. This guarantees smooth integration into the existing hardware and software infrastructure.