Engineering topics

Michael A Krainak

Publications and source records attributed to Michael A Krainak.

3 records

NASA NTRS2001

Fiber Grating Coupled Light Source Capable of Tunable, Single Frequency Operation

Fiber Bragg grating coupled light sources can achieve tunable single-frequency (single axial and lateral spatial mode) operation by correcting for a quadratic phase variation in the lateral dimension using an aperture stop. The output of a quasi-monochromatic light source such as a Fabry Perot laser diode is astigmatic. As a consequence of the astigmatism, coupling geometrics that accommodate the transverse numerical aperture of the laser are defocused in the lateral dimension, even for apsherical optics. The mismatch produces the quadratic phase variation in the feedback along the lateral axis at the facet of the laser that excites lateral modes of higher order than the TM 00 . Because the instability entails excitation of higher order lateral submodes, single frequency operation also is accomplished by using fiber Bragg gratings whose bandwidth is narrower than the submode spacing. This technique is particularly pertinent to the use of lensed fiber gratings in lieu of discrete coupling optics. Stable device operation requires overall phase match between the fed-back signal and the laser output. The fiber Bragg grating acts as a phase-preserving mirror when the Bragg condition is met precisely. The phase-match condition is maintained throughout the fiber tuning range by matching the Fabry-Perot axial mode wavelength to the passband center wavelength of the Bragg grating.

Michael A Krainak↗

NASA NTRSDate not supplied

Photonic Integrated Circuit TUned for Reconnaissance and Exploration (PICTURE)

The mid-infrared (MIR) spectral range (3-5 μm) is of particular interest for remotely sensing gaseous molecules such as H2O, CO2, CH4, N2O, CO, NH3, and other compounds. The infrared spectra of planets, moons, comets, and asteroids are rich in information, including gas composition and surface mineralogy. Significant advances in technology have emerged for ground-based telescopes, including the higher spectral resolution permitted by cross-dispersed instruments and heterodyne techniques. New technologies offer the opportunity to break this barrier, by using solid- state photonics. In the past three years, under the NASA ROSES PICASSO program, we have been developing key components for a revolutionary MIR spectrometer: Photonic Integrated Circuit TUned for Reconnaissance and Exploration (PICTURE), which is based on integrated photonics technology that offers ultra-small size, weight, and power (SWaP) with non-moving parts and low cost for future planetary missions. In this paper, we will describe our science and technology development progress leading to demonstrating the concept and functionalities of the PICTURE instrument. The photonic integrated circuit spectrometer (PICS) of the PICTURE instrument uses an integrated heterodyne detection scheme to significantly reduce SWaP and improve sensitivity. Our program goals are to advance the building blocks needed for the PICS, which include arrayed waveguide gratings (AWGs), quantum cascade lasers (QCLs) as local oscillators, and quantum cascade detectors (QCDs) as heterodyne detectors. In addition, we are leveraging a NASA SBIR program to develop the toolsets needed to fabricate MIR photonics lanterns (PL). The PL is a critical component that enables PICTURE to bring a signal from the collecting telescope to the PICS, which requires single optical mode inputs. PICTURE focuses on the CO spectral band at 4.6-4.8 μm that is of key importance to cometary science. We also continue to explore future instrument concepts that exploit the broad wavelength potential of the PICS design to perform spectroscopy spanning the full MIR and longwave IR (LWIR) bands. This will have wide applicability in planetary science, for example, to probe the strongest CO2, H2O, and CH4 transitions that are difficult (CH4) or impossible (CO2, H2O) to detect using Earth-based telescopes due to atmospheric opacity. Each integrated-photonics-spectrometer chip will feature a single heterodyne room-temperature laser with a wide wavelength tuning range, or multiple local-oscillator lasers for much broader spectral coverage. The fully developed PICTURE instrument will provide a cost-effective, high-resolution spectrometer for future space applications.

Anthony W Yu↗

NASA NTRSDate not supplied

Photonic Integrated Circuit TUned for Reconnaissance and Exploration (PICTURE)

The mid-infrared (MIR) spectral range (3-5 μm) is of particular interest for remotely sensing gaseous molecules such as H2O, CO2, CH4, N2O, CO, NH3, and other compounds. The infrared spectra of planets, moons, comets, and asteroids are rich in information, including gas composition and surface mineralogy. Significant advances in technology have emerged for ground-based telescopes, including the higher spectral resolution permitted by cross-dispersed instruments and heterodyne techniques. New technologies offer the opportunity to break this barrier, by using solid-state photonics. In the past three years, under the NASA ROSES PICASSO program, we have been developing key components for a revolutionary MIR spectrometer: Photonic Integrated Circuit TUned for Reconnaissance and Exploration (PICTURE), which is based on integrated photonics technology that offers ultra-small size, weight, and power (SWaP) with non-moving parts and low cost for future planetary missions. In this paper, we will describe our science and technology development progress leading to demonstrating the concept and functionalities of the PICTURE instrument. The photonic integrated circuit spectrometer (PICS) of the PICTURE instrument uses an integrated heterodyne detection scheme to significantly reduce SWaP and improve sensitivity. Our program goals are to advance the building blocks needed for the PICS, which include arrayed waveguide gratings (AWGs), quantum cascade lasers (QCLs) as local oscillators, and quantum cascade detectors (QCDs) as heterodyne detectors. In addition, we are leveraging a NASA SBIR program to develop the toolsets needed to fabricate MIR photonics lanterns (PL). The PL is a critical component that enables PICTURE to bring a signal from the collecting telescope to the PICS, which requires single optical mode inputs. PICTURE focuses on the CO spectral band at 4.6-4.8 μm that is of key importance to cometary science. We also continue to explore future instrument concepts that exploit the broad wavelength potential of the PICS design to perform spectroscopy spanning the full MIR and longwave IR (LWIR) bands. This will have wide applicability in planetary science, for example, to probe the strongest CO2, H2O, and CH4 transitions that are difficult (CH4) or impossible (CO2, H2O) to detect using Earth-based telescopes due to atmospheric opacity. Each integrated-photonics-spectrometer chip will feature a single heterodyne room-temperature laser with a wide wavelength tuning range, or multiple local-oscillator lasers for much broader spectral coverage. The fully developed PICTURE instrument will provide a cost-effective, high-resolution spectrometer for future space applications.

Anthony W Yu↗