OSE Dissertation Defense by Mr. Behshad Roshanzadeh on Development and Demonstration of a Pico-Watt Calorimeter for Optical Absorption Spectroscopy
Departmental News
Posted: May 12, 2020
Title: Development and Demonstration of a Pico-Watt Calorimeter for Optical Absorption Spectroscopy
Date: Thursday , May 14, 2020
Time: 10:30 am - 12:00 pm
The defense will be held online via zoom:
Meeting ID: 942 861 7314
Speaker:
Mr. Behshad Roshanzadeh
Committee Members:
Prof. Wolfgang Rudolph (Chair)
Prof. Stephen Boyd (Co-Chair)
Prof. Mansoor Sheik-Bahae
Prof. Tito Busani
Abstract:
An optical calorimeter for sensitive absorption measurements of non-radiative samples at 4 K was designed, built, and demonstrated. It consists of a cryostat cooled by a commercial pulse tube (PTC) refrigerator, a measurement chamber housing the sample and thermometers, and various fiber-coupled light sources. By employing measures to damp mechanical noise from the environment and active temperature stabilization of critical components of the instrument temperature noise as low as 6 nK/√Hz at 50 mHz was achieved under 15 mW of optical excitation. An optical absorption induced temperature increase of the sample as small as 2.5 nK could be resolved using paramagnetic temperature sensors with SQUID (Superconducting Quantum Interference Device) readout. This resulted in an absorption sensitivity of 0.3 ppm and 0.6 ppb for tunable 30-μW optical excitation from 330 nm to 1700 nm and for 15-mW laser excitation, respectively. The instrument was applied to the characterization of stacks of dielectric films for material science studies and laser mirror development.
